LGL-Freshwater-Fish - Chuitna Coal Project

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LGL-Freshwater-Fish - Chuitna Coal Project
Movement and abundance of freshwater fish in the Chuit
River drainage, Alaska, May through September 2008
Final report by
LGL Alaska Research Associates, Inc.
1101 E. 76th Ave., Suite B
Anchorage, AK 99518
For
PacRim Coal, L.P.
1007 3rd Avenue, Suite 304
Anchorage, AK 99501
LGL Report P1030
February 18, 2009
Movement and abundance of freshwater fish in the Chuit
River drainage, Alaska, May through September 2008
Prepared by
Matthew J. Nemeth, Benjamin C. Williams, Amy M. Baker,
Christopher C. Kaplan, Michael R. Link, Scott W. Raborn, and
Justin T. Priest
LGL Alaska Research Associates, Inc.
1101 E. 76th Ave., Suite B.
Anchorage, AK 99518
(907) 562-3339
For
PacRim Coal, L.P.
1007 W. 3rd Avenue, Suite 304
Anchorage, AK 99501
LGL Final Report P1030
February 18, 2009
2008 Chuit River Fisheries Monitoring Report – Final Report
Please cite as:
Nemeth, M.J., B.C. Williams, A.M. Baker, C.C. Kaplan, M. R. Link, S. W. Raborn and
J.T. Priest. 2009. Movement and abundance of freshwater fish in the Chuit River
drainage, Alaska, May through September 2008. Final report prepared by LGL Alaska
Research Associates, Inc., Anchorage, Alaska for PacRim Coal, L.P. 159 p.
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2008 Chuit River Fisheries Monitoring Report – Final Report
Executive Summary
Fish were captured at several locations in the Chuit River watershed in 2008 as part of a
multi-objective project designed to describe fish movements and species composition,
estimate abundance of juvenile Chinook (Oncorhynchus tshawytscha) and coho (O.
kisutch) salmon, and establish a time series designed to detect and measure potential
effects of future mine development on fish production. An estimated 37,424 (+/- 4,148)
coho salmon smolts migrated to sea from the Chuit River watershed in 2008, based on
fish marked in three upstream tributaries and fish examined in the mainstem river.
Abundance of Chinook salmon smolts could not be estimated due to scarcity of fish at the
mark sites. The estimated number of coho salmon smolts migrating from the study
tributaries was 8,878 from Stream 2002, 7,790 from Stream 2003, and 4,941 from Stream
2004. Most fish considered smolts were age-2 (two winters spent in fresh water), and
were larger than 90 mm in length; some fish younger or smaller also smolted in 2008, but
the number was uncertain due to behavioral differences of these fish among sites.
The life history of juvenile coho salmon from the Chuit River watershed appears to be
one in which fry hatch in the spring and are moving within the natal tributaries in early to
mid summer. We saw no major movement into or out of the tributaries by these age-0
fish, although some fish may have been too small to be captured by the gear. After
overwintering within the tributaries, some leave for the ocean in the spring of the next
year; these age-1 smolts appeared to be the larger fish of their age class, and mostly
exceeded 80 mm in length. Migration of age-1 smolts ceased by mid July. Afterwards,
additional age-1 fish migrated from the tributaries down into the mainstem Chuit River,
but appeared to be pre-smolts destined to overwinter in the mainstem river before
emigrating to sea the next year as age-2 fish. A third group of age-1 fish remained in the
tributaries, where they overwintered before migrating to sea in the early summer of the
next year, as age-2 smolts. It was these age-2 fish smolting directly from the tributary
that accounted for the majority of smolts we found in 2008, as they migrated in a distinct
pulse extending from early June through mid July. Age-2 fish within the tributaries were
relatively large in size (31% were larger than 120 mm), and were larger than age-2
counterparts in the mainstem river. Larger age-2 fish migrated earlier in the season than
smaller age-2 fish.
V-shaped weirs were installed on all three study tributaries to capture fish moving
downstream and into the mainstem Chuit River. The weirs successfully allowed fish
migrating in and out of the tributaries to be censused from early June through September,
with some exceptions at high water in September. In May, partial weirs on two streams
indicated that few, if any, fish were moving in the streams while ice breakup was
underway, water was high, and water temperatures were low (~ 2° C, 36° F). The weir
systems enabled all of the coho smolt emigration in streams 2003 and 2004 to be
sampled, indicating that these two streams can successfully be monitored as the control
and impact streams needed for the multi-year before-after control-impact (BACI) study
designed to test for impacts from development in Stream 2003. The weir on Stream 2002
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enabled fish to be counted for most of the period from early June through mid September,
as intended to address information requested for the baseline period through 2008.
The upstream migrations of adult salmon differed among the three study tributaries. Low
numbers of adult coho salmon moved into streams 2002 and 2003 in late July, but not
into Stream 2004. A second, larger pulse of adult coho salmon moved into all three
tributaries from early to late September, at nearly identical times. Total numbers of adult
coho salmon were the greatest in Stream 2002 (estimated range: 2,336 to 2,903),
followed by Stream 2003 (1,983 to 2,313) and Stream 2004 (269 to 726). Some fish
likely entered Stream 2004 undetected. Adult Chinook salmon were more numerous in
Stream 2002 (217 to 341) than in Stream 2003 (21 to 80) and Stream 2004 (77 to 153).
Low numbers (6 to 50 per stream) of adult sockeye (O. nerka) salmon returned to all
three streams. Adult pink (O. gorbuscha) and chum (O. keta) salmon were present
mainly in Stream 2002 (4 adult chum salmon, 232 to 436 pink salmon); a few adult pink
salmon were also seen in Stream 2003 (1 to 4).
Other fish had obvious migratory patterns between the study tributaries and the mainstem
Chuit River. Lamprey (primarily Arctic [Lampetra camtschatica], but also a few Pacific
[L. tridentate]) moved in large numbers from streams 2002 and 2003, but in fewer
numbers from Stream 2004. Rainbow trout (O. mykiss) and Dolly Varden char
(Salvelinus malma) moved into and out of each stream consistently, but in low numbers
relative to coho salmon. A large number of newly hatched rainbow trout fry emerged
from a side tributary of Stream 2004 in mid summer. Few juvenile Chinook salmon were
captured in the three tributaries and juvenile pink and chum salmon were rare or absent.
Overall, the results on fish species composition and migratory patterns provide new
baseline information, support many conclusions reached by earlier studies, and provide
useful estimates of the abundance coho salmon in the tributaries and their contribution to
the overall Chuit River salmon production. The results also provide some information on
possible overwintering patterns based on size classes of fish present in late fall and early
spring. Abundance of adult coho salmon was higher than noted in prior studies, and the
documentation of adult sockeye salmon appears to be the first within the study tributaries.
Juvenile coho salmon life history patterns were mostly consistent with prior studies, as
was the scarcity of large rainbow trout moving in the systems in the fall. Species
differences among the three tributaries were consistent with their relative size and
location within the watershed; for example, the decrease in adult pink salmon abundance
from downstream to upstream was consistent with their tendency to not migrate far
upstream to spawn. The relative contribution of coho salmon smolts from the study
tributaries, especially Stream 2003, to the overall watershed provides context for the
assessment of the potential effects of the proposed mining operation. The ability to
monitor coho salmon smolts in future years to detect and understand such effects appears
feasible, and is an important result from 2008.
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Table of Contents
Executive Summary ........................................................................................................... iii
List of Tables .................................................................................................................... vii
List of Figures ................................................................................................................... vii
List of Photos ..................................................................................................................... ix
List of Appendices ............................................................................................................. ix
1.0 Introduction....................................................................................................................1
1.1 Background and Purpose ...........................................................................................1
1.2 Study Scope and Objectives ......................................................................................2
1.3 Study Design Overview .............................................................................................3
1.3.1 Objective 1: Describe the movement and abundance of fish moving into
and out of streams 2002, 2003, and 2004. ..........................................................3
1.3.2 Objective 2: Describe the effects of development on Stream 2003 on
production of Chinook and coho salmon smolts. ...............................................3
1.3.3 Objective 3: Estimate the proportion of fish produced within the Chuit
River watershed that is contributed by Stream 2003. .........................................4
1.3.4 Objective 4: Describe overwintering use of Stream 2003 by resident
rainbow trout or Dolly Varden char. ..................................................................5
1.4 Project Updates ..........................................................................................................6
1.5 Final Project Report ...................................................................................................6
2.0 Study Area .....................................................................................................................6
2.1 Chuit River Watershed...............................................................................................6
2.2 Climate and Weather .................................................................................................7
2.3 Hydrology ..................................................................................................................7
2.4 Fish.............................................................................................................................8
2.5 Vegetation and Geology ............................................................................................8
2.6 Status of Development...............................................................................................9
2.7 Access to Study Area.................................................................................................9
3.0 Methods..........................................................................................................................9
3.1 Fish Movement and Abundance in Tributaries..........................................................9
3.1.1 Downstream movement and abundance of fish ..................................................9
3.1.2 Upstream movement and abundance of fish .....................................................12
3.1.3 Data analysis .....................................................................................................15
3.2 Abundance of Coho and Chinook Salmon Smolts in the Chuit River Watershed ..15
3.2.1 Marking of fish .................................................................................................16
3.2.2 Mark-recapture model selection and assumptions ............................................16
3.2.3 Model selection .................................................................................................19
3.3 Fish Biological Characteristics ................................................................................20
3.3.1 Sampling for length, weight, and age ...............................................................20
3.3.2 Body condition..................................................................................................21
3.4 Environmental Sampling Methods ..........................................................................22
3.4.1 Water temperatures and depth – LGL Alaska...................................................22
3.4.2 Water temperatures and discharge – RTI..........................................................22
3.4.3 Precipitation - McVehil-Monnett......................................................................22
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3.5 Data Entry ................................................................................................................23
4.0 Results..........................................................................................................................23
4.1 Sampling Effort........................................................................................................23
4.1.1 Tributaries .........................................................................................................23
4.1.2 Chuit River........................................................................................................24
4.1.3 Gear downtime..................................................................................................24
4.2 Fish Movement and Abundance in Tributaries – Fish Moving Downstream..........25
4.2.1 Fish abundance and species composition..........................................................25
4.2.2 Run timing and biological characteristics of juvenile coho salmon .................28
4.2.3 Run timing and biological characteristics of non-coho salmon species ...........30
4.2.4 Differences in fish species composition among sites .......................................36
4.3 Fish Movement and Abundance in Tributaries – Fish Moving Upstream ..............36
4.3.1 Abundance and species composition ................................................................36
4.3.2 CPUE and run timing of fish groups moving upstream....................................37
4.3.3 Differences in upstream movement among streams .........................................38
4.3.4 Image analysis on the video system..................................................................38
4.3.5 Visual counts during flood events.....................................................................39
4.4 Abundance of Coho and Chinook Salmon Smolts in the Chuit River Watershed ..39
4.5 Environmental Conditions .......................................................................................40
4.5.1 Ice and snow out ...............................................................................................40
4.5.2 Water temperature.............................................................................................40
4.5.3 Discharge ..........................................................................................................41
4.5.4 Precipitation ......................................................................................................42
5.0 Discussion ....................................................................................................................42
5.1 Overview of Fish Species Composition in Tributary Streams ................................42
5.1.1 Fish species and abundance in each stream ......................................................42
5.1.2 Basic run timing of key fish species .................................................................44
5.2 Coho Salmon Ecology within Streams 2002, 2003, and 2004 ................................46
5.2.1 Life history of juvenile coho salmon ................................................................46
5.2.2 Smolt status.......................................................................................................47
5.2.3 Coho salmon size, body condition, and age......................................................48
5.2.4 Chuit River coho salmon relative to other populations in Cook Inlet ..............49
5.3 Abundance of Coho Salmon Smolts in Tributary Streams Versus the Chuit
River Watershed ......................................................................................................49
5.3.1 Estimated abundance of coho salmon smolts in the Chuit River watershed
(mark-recapture model) ....................................................................................49
5.3.2 Proportion of coho salmon smolts produced in Stream 2003 versus entire
Chuit River watershed ......................................................................................51
5.4 Abundance of Chinook Salmon Smolts in Tributary Streams Versus the Chuit
River Watershed ......................................................................................................53
5.5 Overwintering of Stream 2003 by Resident Fish Species .......................................54
6.0 Conclusions and Summary of Key Results..................................................................55
6.1 Objective 1: Describe the Movement and Abundance of Fish Moving Into and
Out of Streams 2002, 2003, and 2004 .....................................................................55
6.2 Objective 2: Describe the Effects of Development on Stream 2003 on
Production of Chinook and Coho Salmon Smolts ..................................................56
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6.3 Objective 3: Estimate the Proportion of Fish Produced within the Chuit River
Watershed that is Contributed by Stream 2003.......................................................56
6.4 Objective 4: Describe Overwintering Use of Stream 2003 by Resident Rainbow
Trout or Dolly Varden Char ....................................................................................57
7.0 Acknowledgements......................................................................................................57
8.0 Literature Cited ............................................................................................................58
List of Tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Table 11.
Table 12.
Table 13.
Table 14.
Summary statistics for the Chuit River and study subdrainages......................63
Locations and operating dates of sampling sites and camps............................64
Fish caught and percent of catch by species and location. ..............................65
Fish catch by location and gear type................................................................66
Species richness, diversity, and evenness from all sampling sites. .................67
Fish movement and direction in Stream 2002 (video and visual counts). ......68
Fish movement and direction in Stream 2003 (video and visual counts). ......69
Fish movement and direction in Stream 2004 (video and visual counts). ......70
Mean, minimum, and maximum length and weight for all species. ................71
Abundance estimates of coho salmon smolts for the Chuit River
watershed in 2008 ............................................................................................72
Mean length and weight for each species by month. .......................................73
Counts of fish movement, by species and direction, at streams 2002,
2003, and 2004.................................................................................................74
Coho salmon marked releases and recaptures by time period and length
group. ...............................................................................................................75
Number of coho salmon smolt observed in Streams 2002, 2003, and
2004 in relation to watershed-wide abundance estimates................................76
List of Figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8
Figure 9.
Figure 10.
Map of the Chuit River drainage, showing the watershed in relation
to the surrounding area...............................................................................77
Location of fish sampling sites in the Chuit River drainage, May
through September, 2008. ..........................................................................78
Historic stream flow in Stream 2003, years 2002 through 2006 ...............79
Historic stream flow in streams 2002, 2003, and 2004 during the
same period in year 2006. ..........................................................................79
Gear operation status for all sampling sites. ..............................................80
Gear operation effort for all sampling sites. ..............................................81
CPUE at each site, all fish species combined. ...........................................82
CPUE and discharge for two size classes of juvenile coho salmon...........83
CPUE and water temperature for two size classes of juvenile coho
salmon. .......................................................................................................84
Daily upstream and downstream movements of rainbow trout in
streams 2002, 2003, and 2004 (weir and video data combined) ...............85
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Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
Figure 20.
Figure 21.
Figure 22.
Figure 23.
Figure 24.
Figure 25.
Figure 26.
Figure 27.
Figure 28.
Figure 29.
Figure 30.
Figure 31.
Figure 32.
Figure 33.
Figure 34.
Figure 35.
Figure 36.
Figure 37.
Figure 38.
Figure 39.
Figure 40.
Figure 41.
Figure 42.
Figure 43.
Figure 44.
Figure 45.
Figure 46.
Daily upstream and downstream movements of Dolly Varden in
streams 2002, 2003, and 2004 (weir and video data combined) ..............86
CPUE by age of coho salmon in Stream 2002. .......................................87
CPUE by age of coho salmon in Stream 2003..........................................88
CPUE by age of coho salmon in Stream 2004. ........................................89
CPUE by age of coho salmon in the mainstem Chuit River .................... 90
Juvenile coho salmon lengths by date. ......................................................91
Relative weight by length for juvenile coho salmon. ................................92
Juvenile coho salmon CPUE by location and size group ..........................93
Relative weight by week for juvenile coho salmon, juvenile Chinook
salmon, Dolly Varden, and rainbow trout..................................................94
Relative weight by length of juvenile Chinook salmon, Dolly
Varden, and rainbow trout. ........................................................................95
Arctic lamprey CPUE by location and size group. ....................................96
CPUE and discharge for two size classes of Arctic lamprey.....................97
CPUE and water temperature for two size classes of Arctic lamprey. ......98
Arctic lamprey, Pacific lamprey, and lamprey ammocoete lengths by
date.............................................................................................................99
Adult coho, Chinook, and pink salmon lengths by date. .........................100
Juvenile Chinook salmon CPUE by location and size group. .................101
Juvenile Chinook salmon lengths by date................................................102
Juvenile chum, pink, and sockeye salmon lengths by date......................103
Coastrange sculpin, slimy sculpin, and unidentified sculpin species
lengths by date. ........................................................................................104
CPUE and discharge for two size classes of Dolly Varden. ....................105
Dolly Varden CPUE by location and size group. ....................................106
CPUE and water temperature for two size classes of Dolly Varden .......107
Dolly Varden and rainbow trout lengths by date. ....................................108
Threespine and ninespine stickleback lengths by date. ...........................109
Rainbow trout CPUE by location and size group. ...................................110
CPUE and discharge for two size classes of rainbow trout. ....................111
CPUE and water temperature for two size classes of rainbow trout........112
Upstream and downstream counts of adult coho salmon, at streams
2002, 2003, and 2004 (video and visual counts). ....................................113
The total expanded number of all Chinook salmon counted moving
through the video chute in streams 2002, 2003, and 2004.......................114
The total expanded number of Chinook and jack Chinook salmon
counted moving through the video chute in streams 2002, 2003, and
2004..........................................................................................................115
Travel time for juvenile coho salmon. .....................................................116
Cumulative frequency distribution of coho salmon lengths. ...................117
Mean daily water temperatures at the four sampling locations. ..............118
Daily average, minimum, and maximum water temperatures at all
four sampling sites. ..................................................................................119
Mean daily discharge at streams 2002, 2003, and 2004. .........................120
Standardized water depths for the four sampling sites. ...........................121
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Figure 47.
Figure 48.
Figure 49.
Figure 50.
Figure 51.
Daily precipitation from a weather gauging station on Stream 2004. .....122
Change in length over time within age groups 1 and 2 for coho
salmon. .....................................................................................................123
Emigration timing of age 2+ coho salmon from Stream 2002. ...............124
Emigration timing of age 2+ coho salmon from Stream 2003. ...............125
Emigration timing of age 2+ coho salmon from Stream 2004. ...............126
List of Photos
Photo 1.
Photo 2.
Photo 3.
Photo 4.
Photo 5.
Photo 6.
Photo 7.
Photo 8.
Photo 9.
Photo 10.
Photo 11.
Photo 12.
Photo 13.
Photo 14.
Photo 15.
Photo 16.
Photo 17.
Photo 18.
Photo 19.
Photo 20.
Photo 21.
Photo 22.
Photo 23.
Aerial view of the weir in Stream 2002. ........................................................127
Aerial view of the weir in Stream 2003. ........................................................128
Aerial view of the weir in Stream 2004. ........................................................129
A holding box for fish caught moving downstream through the weir...........130
The fyke net in Stream 200401......................................................................130
The downstream entrance to the underwater video chute, electronics
housing, and battery bank at the weir in Stream 2002...................................131
The ramp for adult salmon traveling upstream in Stream 2003.....................131
A rotary screw trap (RST) on the mainstem Chuit River. .............................132
The upstream rotary screw trap (RST1) fishing at high water levels on
the mainstem Chuit River. .............................................................................132
The upstream rotary screw trap (RST1) fishing at low water levels .............133
The downstream rotary screw trap (RST2) fishing at high water levels
on the mainstem Chuit River. ........................................................................133
The downstream rotary screw trap (RST2) at low water levels.....................134
A partial weir in Stream 2003 fishing during high water in mid May,
2008................................................................................................................134
The weir on Stream 2002 at high water levels, July 31, 2008. ......................135
The full weir in Stream 2002 at low water levels, July 3, 2008. ...................135
The weir in Stream 2003 at low water levels.................................................136
The weir in Stream 2003 at high water levels................................................136
The weir in Stream 2004 at low water levels.................................................137
The weir in Stream 2004 at high water levels................................................137
Coho salmon smolt captured in the mainstem Chuit River. ..........................138
Pacific lamprey captured in Stream 2002. .....................................................138
Image series of two adult rainbow trout moving upstream through the
video chute in Stream 2002............................................................................139
Adult sockeye salmon caught in Stream 2003...............................................139
List of Appendices
Appendix A. Daily gear operation status.......................................................................140
Appendix B. Daily counts (actual and expanded) coho salmon smolts through the
video chute in Stream 2002......................................................................144
Appendix C. Daily counts (actual and expanded) coho salmon smolts through the
video chute in Stream 2003......................................................................146
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Appendix D. Daily counts (actual and expanded) coho salmon smolts through the
video chute in Stream 2004......................................................................147
Appendix E. Daily (actual and expanded) counts of adult coho salmon moving
upstream in Stream 2002. ........................................................................148
Appendix F. Daily (actual and expanded) counts of adult coho salmon moving
upstream in Stream 2003. ........................................................................149
Appendix G. Daily (actual and expanded) counts of adult coho salmon moving
upstream in Stream 2004. ........................................................................150
Appendix H. Daily counts (unexpanded) of fish passing through the video chute in
Stream 2002. ............................................................................................151
Appendix I. Daily counts (unexpanded) of fish passing through the video chute in
Stream 2003. ............................................................................................154
Appendix J. Daily counts (unexpanded) of fish passing through the video chute in
Stream 2004. ............................................................................................157
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1.0 Introduction
1.1 Background and Purpose
The Chuit River watershed, on the west side of Upper Cook Inlet in Southcentral Alaska,
contains extensive coal deposits that have been considered for development since the
early 1960s. The impacts of the proposed open-pit coal mine on the local environment
need to be assessed in accordance with state and federal regulations (described below).
This assessment will be done, in part, by updating an Environmental Impact Statement
(EIS) completed in 1990 with a Supplemental EIS (SEIS), and by addressing information
needed for mine permitting under the Alaska Surface Coal Mining Control and
Reclamation Act (ASCMCRA). The SEIS will draw on new environmental baseline
studies to fill information gaps, update old information, and address regulatory
requirements.
Some of the information needed for the SEIS has been obtained by baseline studies of
freshwater fish and habitat conducted in 2006 and 2007. These studies included
descriptions of fish distribution, relative abundance, community composition, and
freshwater habitat (Oasis 2008). Most of this work was conducted on the tributary stream
proposed for development (Stream 2003) and the two adjoining tributaries (streams 2002
and 2004); the work both updated historical information used in the EIS in 1990 (e.g.,
ERT 1984) and provided new data for the SEIS (Oasis 2008).
In late 2007, Federal and State agencies identified additional or remaining information on
fish and water resources needed for the SEIS and for ASCMCRA permitting. This
remaining information related primarily to evaluating fish production, to assessing
impacts from development on fish production, and to additional work with stream flows
or aquatic monitoring. Information for the Federal processes (i.e., the SEIS) relates to
needs under the National Environmental Policy Act (NEPA), and was meant to be
addressed by a year of baseline monitoring in 2008. Information for the State processes
relates to the ASCMCRA permitting process, and was meant to be addressed by
monitoring coho and Chinook salmon in the baseline year (2008) and the following three
years prior to mine construction (the predevelopment period, 2009-2011).
Through late 2007 and early 2008, the agencies worked with PacRim Coal, LP and LGL
Alaska Research Associates, Inc. to identify research components that would provide this
information and to develop a final study design for a multi-year fish monitoring study
that would include the remaining fisheries information needed for the SEIS and the
ASCMCRA permitting process. This design was finalized in April of 2008, and LGL
Alaska Research Associates, Inc. began field work the same month. This report describes
the results of the first year of this monitoring study, which went from April 21 through
September 30, 2008, and was intended to complete the baseline studies needed (for the
SEIS) and to begin the studies needed for the predevelopment period (for ASCMCRA).
Although extensive, this study was meant to include only components related to fish
movement and abundance, and not those that were either unrelated or already being
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2008 Chuit River Fisheries Monitoring Report – Final Report
studied. Project components intended to be covered by this study versus those meant to
be addressed elsewhere are shown below:
Addressed in the fish monitoring study
Juvenile fish outmigration and
abundance
• Detection of potential effects from
mining on fish in streams 2003 and
2004
• Smolt production in Stream 2003 and
contribution to the overall production
in the Chuit River watershed
• Winter habitat use by Dolly Varden
and rainbow trout
•
•
•
•
Addressed elsewhere
Monitoring for impacts on Stream
2002
Summary of adult salmon distribution
and spawning habitat
Instream flow
1.2 Study Scope and Objectives
Information related to freshwater fish in the Chuit River has been acquired by a series of
studies from 1982 through 1984 (e.g., ERT 1984) and again from 2005 through 2008
(e.g., Oasis 2008, 2009). These studies have provided much, though not all, of the
baseline information needed to write a Supplemental Environmental Impact Statement
(SEIS), which will update the original EIS (EPA 1990). The remaining information
needed for the SEIS was summarized in a letter from the Environmental Protection
Agency on November 15, 2007, and modified thereafter in the course of several meetings
from December 2007 into April 2008.
Other information must also be acquired as part of the permitting process under
ASCMCRA, as described in a letter from the Alaska Department of Natural Resources on
November 13, 2007 and modified in the course of meetings from December 2007 into
April 2008. Much of this information was related to assessing the impacts of
development upon fish within Stream 2003, the tributary watershed in which most
mining will occur. In addition, the size of this impact relative to the larger watershed
needs to be evaluated.
Most of the remaining fisheries information and data requirements for the SEIS and
ASCMCRA process centered around issues of fish production within the tributary to be
mined (Stream 2003), on identifying any changes in this production caused by mine
development, and on describing the relative effect of the changes in this tributary on the
overall Chuit River watershed. Chinook and coho salmon are abundant within the Chuit
River watershed and are important for subsistence, recreational, and commercial fisheries
within the local and surrounding Cook Inlet region.
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2008 Chuit River Fisheries Monitoring Report – Final Report
The specific objectives of the freshwater fish study described in this report were:
1. Describe the movement and abundance of fish moving into and out of streams
2002, 2003, 2004.
2. Describe the effects of development on Stream 2003 on production of Chinook
and coho salmon smolts.
3. Estimate the proportion of fish production within the Chuit River watershed that
is contributed by Stream 2003.
4. Describe overwintering use of Stream 2003 by resident rainbow trout or Dolly
Varden char.
Objectives 1, 3, and 4 were intended to be addressed in one year of monitoring (the
baseline year in 2008). Objective 2 was designed to be addressed by monitoring through
the predevelopment period (2008-2011), thereby providing a time series of four years of
data.
1.3 Study Design Overview
1.3.1 Objective 1: Describe the movement and abundance of fish moving into and out of
streams 2002, 2003, and 2004.
Weirs were installed in the lower reaches of streams 2002, 2003, and 2004 in May 2008,
as close to the confluence with the Chuit River and as soon after ice-out as possible
(Figures 1 and 2). Fish moving downstream were diverted into a holding box where they
were counted, identified to species, subsampled for basic biological information, then
released downstream. Any fish that avoided the holding box through the breach in the
weirs were recorded on a video camera when migrating downstream. Fish moving
upstream were counted and identified to species and size group by being funneled past
the video camera. Weirs at each site were operated 24 hours per day, 7 days a week
during normal conditions. The study period ranged from early May through the end of
September, depending on the stream. Information from this objective will provide fish
community and life history information needed to assess impacts under the NEPA and
develop the SEIS. Estimates of coho and Chinook salmon smolt abundance can also be
used in assessments for mitigation and restoration.
1.3.2 Objective 2: Describe the effects of development on Stream 2003 on production of
Chinook and coho salmon smolts.
The effects of mining on the populations of Chinook and coho salmon in Stream 2003
will be assessed using both before-after control-impact (BACI), and before-after (BA)
study designs (Green 1979). Smolt abundance will be monitored before and after mine
development in Stream 2003 to test whether annual abundance changes using a
traditional BA study design. The BACI study design will be accomplished by monitoring
smolt abundance concurrently in two streams, one to serve as the control (Stream 2004)
and one to serve as the potential impact (Stream 2003). The ability to detect an effect
from mining will be a function of the number of years of monitoring, the size of any
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effect, and the variability in the dataset (Murphy and Myors 1998). The ratio of smolts in
Stream 2004 to Stream 2003 in the four years before disturbance will be compared to the
ratio in multiple years after disturbance on Stream 2003, but before any potential
disturbance on Stream 2004 (which should be no sooner than the year 2018). Such ratios
successfully identified multiple effects of habitat alteration on juvenile coho salmon in
Oregon, using 4 years of monitoring before and after habitat modification (Solazzi et al.
2000). The use of ratios increases the tolerance of the analysis to interannual variability;
the important element is that any population size trends during the pre-treatment period
are similar between the control and impact streams (e.g., populations not increasing in
one stream while declining in another). Covariation in coho and Chinook salmon smolt
abundance in streams 2003 and 2004 will be reported each year, and statistical
correlations will be evaluated for entire populations and for subsets such as age classes.
Results from the construction and operation period will include comparisons between
streams 2003 and 2004 versus changes within each stream, while controlling for aspects
of run timing, age, or size that differed between the streams during the predevelopment
period (2008-2011).
Smolts will be the life stage monitored because the production of these fish is closely
linked to habitat conditions (Bocking and Peacock 2005), and because the relatively low
interannual variability of smolt abundances (relative to adult returns and spawning
escapements) increases the power to detect a difference after an impact. High interannual
variability in adult salmon returns is due, at least in part, to the wider range of variables
that affect adult salmon in the ocean, including variability in fishery harvest rates.
Elsewhere in Cook Inlet, smolt abundances varied by approximately 25% on the Kenai
River over 5 years (1999−2003) and by approximately 20% on Cottonwood Creek over
four years (2000−2003). Concurrent adult escapements varied by over 300% on the
Kenai River and 66% on Cottonwood Creek (data from Lafferty et al. 2007).
Results from Objective 2 will help address ASCMCRA permitting requirements by
helping to identify and then quantify the size of any effects of mine development and
operation on the coho and Chinook salmon populations in Stream 2003.
1.3.3 Objective 3: Estimate the proportion of fish produced within the Chuit River
watershed that is contributed by Stream 2003.
The abundance of coho and Chinook salmon smolts from streams 2002, 2003, and 2004
was estimated using the number of those fish counted at the weir and video station on
each stream (Objective 1, above). Smolt abundance for the entire Chuit River watershed
was estimated using mark-recapture methods; salmon smolts leaving streams 2002, 2003,
and 2004 were marked at the weirs, then recaptured downstream in the mainstem river
using rotary screw traps (RSTs). The estimated abundance of smolts in the entire Chuit
River drainage was a function of the number of fish marked in the tributaries, the number
of fish examined in the Chuit River, and the number of these examined fish that had
marks. The watershed-wide abundance estimate was then compared to the proportion
counted through the weir in Stream 2003 to estimate the contribution from Stream 2003
to the Chuit River drainage as a whole.
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A separate assessment, based on modeling the amount of habitat available to juvenile
coho and Chinook salmon, will be performed to see what the theoretical production
would be (based on data from other streams), and what proportion of the juvenile salmon
production in the entire Chuit River would be expected to come from Stream 2003.
Observed and theoretical production will allow an assessment of the relative effects of
mining on smolt production in the entire Chuit River watershed. These will also provide
a more robust estimate of the potential smolt production than a single estimate from
2008.
The linkage between freshwater habitat and fish production has been documented by
numerous peer-reviewed studies showing a consistent relationship between quantity and
quality of freshwater habitat and production of salmon and other fishes (e.g., Bradford et
al. 1997; Shortreed et al. 1999; Parken et al. 2006; Rahel and Jackson 2007).
Consequently, habitat quantity and/or quality is now used to manage salmon populations
for applications as diverse as predicting smolt or adult production, setting harvest limits
or escapement goals, identifying stream reaches to prioritize for conservation and
restoration, and estimating the production potential of a stream (e.g., Bocking and
Peacock 2005). The approach is especially useful for species with relatively long
freshwater residence, and is now used to manage populations of Chinook, coho, and
sockeye salmon in British Columbia, Oregon, and Washington (Nickelson et al. 1992;
Sharr et al. 2000; PFMC 2003; Bocking and Peacock 2005; Parken et al. 2006; Volkhardt
et al. 2007). A similar approach has been used for decades to estimate the production
capacity of sockeye salmon from rearing lakes (Koenings and Burkett 1987; Shortreed et
al. 1999), and has been investigated elsewhere in Alaska (e.g., Anderson and Hetrick
2004; Nemeth et al. 2009).
The relative contribution of smolts from Stream 2003 to the entire Chuit River watershed
will be used for both the SEIS and the ASCMCRA permitting processes.
1.3.4 Objective 4: Describe overwintering use of Stream 2003 by resident rainbow trout
or Dolly Varden char.
This objective was to be addressed in two components. The first of these was the
overwintering study conducted in the winters of 2006/2007 and 2007/2008 by Oasis
Environmental (Oasis 2009; the final report from which was not complete at the start of
2008). The second component was to tag rainbow trout with radio transmitters in
summer and fall of 2008 in Stream 2003 to describe any use of the stream through the
following fall, winter, and spring. We did not place transmitters in any rainbow trout in
2008, for reasons described later in this report.
Information from Objective 4 is to be used as part of the SEIS and ASCMCRA
permitting processes. Data from Oasis Environmental (Oasis 2009) and from Objective 1
of this study will help assess the use of Stream 2003 by overwintering fish.
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1.4 Project Updates
Project updates and data summaries were delivered on July 3 and August 6 and made
available to agencies. These reports focused on where effort had been spent, what
objectives were undertaken, and the counts of fish through each weir to date. Only basic,
preliminary data analyses were reported. The monthly reports provide a supplement to
the final report on topics such as effort, conditions, and problems encountered during the
study. Data and results presented in this final report supersede those presented in the
monthly reports.
1.5 Final Project Report
The final report emphasizes sampling effort, data analysis, and results. It was submitted
in three stages: draft reports on December 19, 2008 and January 30, 2009, and the final
report in February 2009. The February report is intended to be used as a reference for the
SEIS, consent applications, and other regulatory-related documents.
2.0 Study Area
2.1 Chuit River Watershed
The Chuit River watershed is a 4th-order river (Strahler 1957) that drains into the western
shoreline of Upper Cook Inlet, 67 km (42 mi) southwest of the city of Anchorage, in
Southcentral Alaska (Figure 1). The watershed flows southeast and drains an area
approximately 139.4 km2 (96,000 acres). The watershed is in lowlands with elevations
generally below 305 m (1,000 ft) and bordered to the west by the Tordrillo Mountains,
part of the Alaska Range (RTI 2007). The Chuit River watershed is unglaciated and
consists of seven main subdrainages. In general, tributaries begin to freeze in late
October and ice break-up occurs in late April. By early May, streams are mostly ice free
(RTI 2007). Three of the lower tributaries that enter from the north (streams 2002, 2003,
and 2004) are relatively similar in size (Table 1), and are the study streams described in
this report (Figure 1).
Stream 2002 (a.k.a. Lone Creek) is a 3rd-order stream draining 55.4 km2 (13,660 acres),
and enters the Chuit River approximately 14.8 km (9.2 mi) upstream from the ocean.
The mean annual discharge of Stream 2002 is 1.2 m3/s (43.08 ft3/s) and the stream is 39
km (24.2 mi) long (Table 1; RTI 2007). The sampling site on this tributary was 1.9 km
(1.2 mi) upstream from the confluence with the Chuit River, at an elevation of 75.6 m
(248 ft) above sea level (Figure 2).
Stream 2003 (a.k.a. Middle Creek) is a 2nd-order stream draining 36.3 km2 (9,126 acres),
and enters the Chuit River approximately 18 km (11.2 mi) upstream from the ocean. The
mean annual discharge of Stream 2003 is 1.0 m3/s (33.90 ft3/s) and the stream is 30 km
(18.6 mi) long (Table 1; RTI 2007). The sampling site on this tributary was 1.9 km (1.2
mi) upstream from the confluence with the Chuit River, at an elevation of 104.9 m (344
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ft) above sea level (Figure 2). The proposed coal mine development lies within this
watershed.
Stream 2004 (a.k.a. Base Creek) is a 3rd-order stream draining 38.4 km2 (9,501 acres),
and enters the Chuit River 30.8 km (19.1 mi) upstream from the ocean. The mean annual
discharge of Stream 2004 is 0.9 m3/s (32.84 ft3/s) and the stream is 33 km (20.5 mi) long
(Table 1; RTI 2007). The sampling site on this tributary was 1.7 km (1.1 mi) upstream
from the confluence with the Chuit River, at an elevation of 194.8 m (639 ft) above sea
level (Figure 2).
All three streams have numerous fish-bearing side tributaries. In streams 2002 and 2003,
we were able to place weirs downstream of where the lowest of these side tributaries
enter, thereby capturing all fish migrating from the watersheds of streams 2002 and 2003
into the Chuit River. In Stream 2004, one side tributary enters downstream of the lowest
point we could place a weir in Stream 2004. This side tributary, known as Stream
200401, was sampled separately, and the results added to those from the overall
watershed in Stream 2004. Stream 200401 is a 2nd-order stream that enters Stream 2004
approximately 0.5 km (0.3 mi) upstream from the confluence with the Chuit River, and
1.2 km (0.7 mi) below the sampling site in Stream 2004 (Figure 2). The confluence of
the two streams is about 189.9 m (623 ft) above sea level.
2.2 Climate and Weather
The study area lies in a transitional zone between maritime and continental climate zones
(RTI 2007), which are noted for mild winters, cool summers, and moderate precipitation.
For the 30-year period from 1971 to 2000, air temperatures at the nearby community of
Beluga ranged from 6.2 to 19.9° C (43.1 to 67.9° F) in the summer (June through August)
and −3.7 to −1.2° C (7.3 to 29.8° F) in the winter (November through March; ACRC
2008). In summer, prevailing winds are from the south and southwest, and daylight
peaks at 19.5 hours. In winter, prevailing winds are from the north-northwest to northnortheast (McVehil-Monnett 2006), and daylight drops to a low of 5.5 hours. A weather
monitoring station has operated on Stream 2004 since the year 2006 (McVehil-Monnett
2006).
2.3 Hydrology
The Chuit River has an estimated mean annual discharge of 10.1 m3/s (354.9 ft3/s) and is
approximately 103 km (64 mi) long, and (Table 1; RTI 2007). Water levels peak in mid
to late May from snowmelt and again from September through October from increased
precipitation (Figures 3 and 4). The Chuit River watershed is typically covered with
snow from October or November through late May. Average annual precipitation in the
community of Beluga (1971−2000) was approximately 26 inches with average annual
snowfall of 81 inches (ACRC 2008).
Flood events have been thought to impact salmonid habitat in the Chuit River watershed
in recent years, including events that occurred since the time of the original baseline work
conducted in the early 1980s. One major flood event was in 1986, two years after the
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original baseline study was completed. The flood occurred over a three-day period in
early October, resulting from unusually high levels of rainfall (Lamke and Bigelow
1988). During the flood, peak discharge for the Chuit River ranged from 566 to 1,416
m3/s (20,000 to 50,000 f3/s), and roughly 85 to 198 m3/s (3,000 to 7,000 f3/s) in the lower
areas of streams 2002 and 2003. Average discharges during the month of October
usually range from about 7.1 to 17 m3/s (250 to 600 f3/s) in the Chuit River, and 0.6 to
2.5 m3/s (20 to 90 f3/s) in lower areas of streams 2002 and 2003 (ERT 1987).
The 1986 flood changed channel depths, reduced substrate size, caused bank erosion and
slope failures, accumulated debris in streams, and formed new channels. Impacts on
salmon habitat differed depending on species, life stage, and the location within the
watershed. In general, effects on available habitat for juvenile salmonids were minimal.
Adult salmon spawning habitat was reduced in many areas and increased in a few areas.
Without any additional flood events, these areas were expected to return to their pre-flood
condition within two to five years (ERT 1987). Other major floods occurred in
Southcentral Alaska in 1995 and 2006 (RTI 2007). The size and effects of these floods
on the Chuit River watershed have not been reported.
2.4 Fish
The Chuit River watershed provides habitat for anadromous and resident fish species,
including juvenile and adult salmonids. Seven species of salmonids are found within the
drainage: rainbow trout, Dolly Varden, and all five species of pacific salmon native to
Alaska (coho, Chinook, pink, chum, and sockeye salmon; EPA 1990). Other resident
species include coastrange sculpin (Cottus aleuticus), slimy sculpin (C. cognatus), Pacific
lamprey, Arctic lamprey, ninespine stickleback (Pungitius pungitius), and threespine
stickleback (Gasterosteus aculeatus).
Salmon migrate through Cook Inlet and enter the Chuit River watershed to spawn.
Beginning in mid June, Chinook salmon enter the Chuit River and migrate upstream to
spawn in early July through mid August. Coho salmon enter the Chuit River and begin
their upstream migration in late July and spawn from late August through October (EPA
1990). Fishery managers with the Alaska Department of Fish and Game (ADF&G) use
the Chuit River as an index of the run strength of Chinook salmon returning to Upper
Cook Inlet (Fox and Shields 2005). Run timing and distribution of adult salmon in the
watershed is described in detail in the report by Oasis (2008).
2.5 Vegetation and Geology
The study area within the Chuit River watershed is dominated by mixed woodland
habitat, composed of spruce (white or black) and paper-birch. Shrub vegetation is
dominated by alder species and account for a large portion of the canopy cover (HDR
2006). The watershed contains numerous bogs, ponds, and small lakes; most ponds and
lakes eventually become muskegs (EPA 1990). Riparian vegetation is mostly alder,
willow, and various grass species. Vegetation overhanging stream banks provides cover
for both resident and anadromous fish species (Oasis 2006).
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The study area is characterized by morainal topography (EPA 1990) and composed of
Tertiary sedimentary rock (RTI 2007). Over time, streams have carved out the
underlying sedimentary rock forming valleys (EPA 1990). A steep sloped valley occurs
in the study area from the Chuit River mouth to the confluence with Stream 2004 (Oasis
2006). Tributaries and floodplains within the Chuit River watershed are composed of
alluvium deposits. Well sorted sand and gravel are deposited in stream channels, and
finer grained sediments, silt and sand, occur as overbank or floodplain deposits (RTI
2007). Alluvium deposits generally range from 3 to 12 m (10 to 30 ft) in depth (EPA
1990).
2.6 Status of Development
Limited development and exploration has occurred within the Chuit River watershed.
Exploration of natural resources began in the 1960s and continued in the 1970s with core
drilling (EPA 1990). In 1981, 1982, and 1986 exploratory drilling was conducted to
create a geologic model of the proposed mine site (RTI 2007) that includes upper
portions of Stream 2003. Networks of gravel roads, some of them old logging roads from
mid 1970s (EPA 1990), connect the community of Beluga to the villages of Tyonek and
Shirleyville. Secondary roads provide access to surrounding areas.
2.7 Access to Study Area
A secondary road provides access to the study area. The road crosses the Chuit River
approximately 5.9 km (3.7 mi) upstream from the ocean, then heads northwest alongside
the river until the confluence with Stream 2002. The road then continues alongside
Stream 2002 until ending approximately 0.8 km (0.5 mi) from the confluence. Trails that
follow seismic exploration lines are found as far upstream as Stream 2004, including
trails leading to streams 2002 and 2003. No developed roads or permanent structures
occur in the study area. Access to Stream 2004 was provided by helicopter.
3.0 Methods
3.1 Fish Movement and Abundance in Tributaries
3.1.1 Downstream movement and abundance of fish
Downstream movement of fish was monitored at six different locations within the Chuit
River watershed, from May through September. In streams 2002, 2003, and 2004,
downstream movement of fish was monitored primarily with a fine-meshed weir; fish
moving downstream past the weir were either diverted into a trap box where they were
counted and handled, or escaped through an intentional breach in the weir which was
outfitted with a video camera that allowed species identification and counting (but not
capture). Fyke nets and minnow traps were used sporadically as ancillary gear types to
provide assessments at times when weirs were impractical (primarily in the early season).
In Stream 200401 (tributary to Stream 2004), a fyke net was used to capture fish
migrating downstream from Stream 200401 into Stream 2004. For most analyses, data
from the Stream 200401 fyke net were added to data from the rest of the Stream 2004 so
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that data presented from all three study streams included data from all side tributaries. In
a few cases, Stream 200401 data afforded a level of resolution not available within the
watershed, such as the timing of resident species moving from a 2nd-order to a 3rd-order
stream; in these cases, Stream 200401 data are reported separately from the rest of
Stream 2004.
All traps and nets were visited at least twice daily when operating full-time. Under
certain conditions, such as high water events, sampling was halted or gear was removed
for the safety of downstream migrating fish and the crew, and to protect gear from
damage.
Weirs
Weirs were built on the three study tributaries to capture all fish traveling downstream.
Weirs were placed approximately 1.7 to 1.9 km (1.1 to 1.2 mi) upstream from the
confluence with the Chuit River. In streams 2002 and 2003, this placement captured all
tributaries of the streams. In Stream 2004, the weir was placed at the lowest possible
location able to support a weir. Downstream of the weir in Stream 2004 a tributary,
Stream 200401, enters from the northwest. Because Stream 200401 enters below the
weir, a fyke net was placed to monitor fish movement (Figure 2).
Weirs were constructed from panels built from aluminum tubing and covered with plastic
mesh (Vexar®). The aluminum tubing was 3.8-cm (1-1/2-in) square with a 0.32-cm (1/8in) wall thickness. A full size panel was 1.2 m high and 2.4 m long (4 x 8 ft) and faced
with 0.64-cm (1/4-in) mesh, 0.95-cm (3/8-in) mesh, or 1.27-cm (1/2-in) mesh. Different
combinations of mesh size and panel heights (0.6 to 1.2 m; 2 to 4 ft) were experimented
with during different periods of water volume and debris loads. In general, panels with
the largest mesh were installed in areas with the highest water velocity, where the panels
would be set nearly parallel to the current. Similarly, shorter panels (0.61 m; 2 ft) were
strategically placed to allow spillover during high water events to reduce stress on the
weir. Where water velocity was slower, panels were turned more perpendicular to the
flow and a smaller mesh was used to prevent small fish from passing through the weir
panel. Use of the 1.27-cm (1/2-in) mesh was critical for maintaining the weir during
periods of high flow and debris load.
Landscape fabric was used under the weirs to prevent erosion and scouring of substrate.
Sandbags were placed in rows along the upstream and downstream sides of the panels to
secure both the landscape fabric and the weir. Rebar and steel pipe were pounded into
the river bottom and fastened to the aluminum panels for stabilization against the current.
Rope was used to tie rebar in a crisscrossing pattern within the weir, and to trees along
the shore to prevent the panels from folding back or shifting under pressure.
Modifications and repairs occurred throughout the season to troubleshoot or prepare for
high water events.
The weirs were designed to divert downstream migrating fish into a holding box where
fish were then sampled. Weirs were arranged in a “V” formation with weir panels
leading into the mouth of a corrugated, flexible plastic pipe placed in the center of the
“V” (Photos 1 through 3). This 38.1-cm (15-in) diameter pipe ran 7.6 m (25 ft) to a
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plywood holding box set into the stream. Fish moving down the pipe collected in this
box (Photo 4), which was checked twice per day or more frequently during high water
events. Holding boxes on all three streams were shaped like an “L.” Holding boxes in
streams 2002 and 2004 were approximately 1.4 m (4.6 ft) at the widest part by 1.8 m (6
ft) long. The holding box in Stream 2003 was larger, approximately 1.5 m (5 ft) at the
widest part by 1.8 m (6 ft) long.
The energy of the water entering the holding box was dissipated by a splash panel that
dispersed the flow. The entry height of the pipe was adjustable, and was raised or
lowered to reduce the velocity of incoming water. All holding boxes had three chambers
separated by slotted baffles through which fish could pass. The baffles reduced the water
velocity in the box and provided calm holding water for fish. The slots allowed fish to
pass from the most unprotected areas (the pipe entrance) to the most protected (the
downstream chambers), and separated fish by size to limit size induced predation. Much
of the holding box was faced with 0.64-cm (1/4-in) plastic mesh to provide water and
dissolved oxygen circulation to the fish and to prevent the holding box from overfilling
with water.
Video cameras
A video system was installed at each weir to record fish moving upstream and
downstream through the intentional breach in the weir. The main purpose of the breach
was to allow upstream movement of fish past the weir; the video system is thus described
in detail in Section 3.1.2. It is important to note, however, that the breach also allowed
fish to avoid the pipe that led to the holding box (described above). Fish using the video
breach were not captured and handled, but were identified and counted using the video
system.
Fyke nets and minnow traps
Fyke nets and minnow traps were used as ancillary gear to test for fish not captured in the
weirs or RSTs. On the tributaries, fyke nets were also used to provide an early indicator
of fish presence in the system before the weirs were operational. A fyke net was fished
continuously in Stream 200401 (the stream entering below the weir at Stream 2004;
Photo 5).
Fyke nets were supported by 1.7 x 1.8 m (5.6 x 5.9 ft) stainless steel frames faced with
0.32 x 0.64 cm (1/8 x 1/4 in) knotless netting and deployed with mesh wings. A funnel
led from the center of the frame into a cod end, where the fish were collected after
passing through a series of constrictions designed to keep trapped fish from escaping.
The minnow traps were standard Gee traps (http://www.sterlingnets.com/specialty.html)
that consisted of two funnels placed end to end. The traps were baited with sterilized
salmon roe and fished for varying lengths of time (2 to 12 hours). Each trap was made of
0.32-cm (1/8-in) black metal mesh, and was approximately 0.36 m (1.2 ft) long when
assembled.
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3.1.2 Upstream movement and abundance of fish
The breach in the weir that was placed to allow upstream movement of fish was outfitted
with a chute that housed a video camera system designed to record fish passage. As
noted above (Section 3.1.1), this video system was intended to primarily identify and
count upstream-moving fish, but was also able to identify and count any downstreammoving fish that avoided the chute leading to the holding box.
The video system was unable to count all fish during some high water events when the
water was either too turbid to capture fish on camera, or when fish moved upstream by
leaping over the weir and thus avoided the video chute. In these cases, visual
observations were used to estimate fish passage, and these estimates were added to those
obtained with the camera.
Video system design, configuration, and operation
The video system consisted of a 0.5 x 0.5 x 0.9 m (1.5 x 1.5 x 3 ft) fish passage chute
(Photo 6), a camera view window, and camera housing. Custom-built underwater lights
were installed in the chute to provide night-time illumination and enhance day-time
imagery. Each video system used a single underwater camera, separated from the fish
passage chute by a removable, laminated glass window. Supporting components were
installed on the stream bank inside electric fencing for protection from animals. Support
components included a weatherproof enclosure housing the digital video recorder (DVR),
a small (15 x 15 cm; 6 x 6 in) imagery viewing monitor, and an AC/DC power supply
consisting of six deep cycle batteries (Photo 6) and a 1000 watt generator. Deflection
wings built from weir materials were added upstream of the chute to prevent large
numbers of downstream moving fish from passing through the video system and instead
direct them toward the weir holding box.
Once installed, all video systems were operated seven days a week, 24 hours a day
through September. Daily maintenance and system checks included charging battery
banks, cleaning chute walls, camera lenses, and camera view window, checking the DVR
hard drives for data storage capacity, and reviewing samples of video from the previous
24 hours.
All underwater cameras were fitted with wide-angle, 2.9-mm (0.1-in) color lenses with a
100-degree field of view (http://www.iasproducts.com). Images were collected at a
resolution of 720 x 480 dots per inch (DPI). Images were transferred through an
underwater coaxial cable to a waterproof camera interface box powering the camera and
then to the digital video recorder (Speco Model DVR-4TN/300; www.specotech.com)
onshore. Each system was set to record video at a rate of seven pictures or “frames” per
second (7 PPS). Systems were also equipped to record fish passage events in 5 second
intervals through motion detection, at a rate of 30 PPS. Motion detection sensitivity was
intended to be set such that adult-sized fish passing through the video chute would trigger
the camera, but most debris or juvenile-sized fish would not, allowing adult passage to be
surveyed via motion detection events. Video was checked daily for the number of
motion detected events which were then either reviewed in full, or subsampled (if >30) to
determine if the motion detection sensitivity was properly set. Motion events were also
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used as a tool for learning in real-time what fish species were present, and to determine if
there was a problem with the system.
Video images were stored on 250-GB internal hard drives (Western Digital #2500).
Depending on the number of motion detection events, one hard drive allowed for storage
of about 15 days of data. As a hard drive reached capacity, it was removed from the
streamside monitoring sites, taken to camp, and reviewed with a DVR unit attached to a
19” monitor (Triview model TLM-1903).
Biologists were trained onsite in the identification of resident fish species before
compiling video data. Video images were identified to species or fish group, then further
placed into size class categories meant to represent the life stages of interest for key
species (e.g., smolts vs. pre-smolts for juvenile coho salmon). Fish passage through the
video system was estimated in two ways. In most cases, fish counts were estimated by
subsampling the first 15 minutes of each hour, and then extrapolating this count to the
next 45 minutes to generate an estimate for that hour. Using this method, each time-lapse
clip was reviewed at 4x to 8x speed for the first 15 minutes of each hour; each time a fish
was detected the images were replayed until the fish was identified to species or group
and to size class, and movement direction was assigned (upstream, downstream, or
indeterminate). The counts from this 15-minute block were then multiplied by four to
generate an estimate of species and size-class specific fish movement for each hour. Fish
passage for each 24-hour cycle was the sum of 24 such expanded hour blocks of 15minute counts.
In some cases, fish counts were estimated by counting fish for the entire hour (not by
subsampling). This was done during periods of high movement by key fish, such as
when pulses of adult salmon moved upstream, or when workers had recently been in the
stream and thus could not be sure that a 15-minute time block would be representative of
the full hour. Full counts during times of high movement reduced much of the potential
sampling error (from subsampling techniques). Full counts were also used to test the
accuracy of subsampling techniques by comparing a limited number of hourly estimates
from the 15-minute subsamples to the full counts for that entire hour.
Fish were able to move both upstream and downstream through the video chute. Because
these fish were not marked, there was no ability to determine whether fish moving past
the video chute were new ones, or ones that had been re-sighted going the other direction
at an earlier time. Therefore, total counts were recorded as ranges; if 100 fish of a
particular group (or species) were sighted going upstream and 50 were sighted going
downstream, the upstream count of that group was estimated to be from 50 to 100 fish.
Visual counts during flood events
Biologists monitored weather forecasts and gathered real-time environmental
information, such as rainfall and changes in stream depth, to assess the potential for
flooding. When a flood was predicted, weirs were arranged to allow for controlled
release of water (spillways) before the force of the water could destroy the weir. These
spillways resulted in places where fish could move upstream around the camera, causing
the cameras to give incomplete counts of fish passage upstream. To account for these
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partial counts, the water release points were designed so that an observer standing on the
bank could count fish moving through the spillways. Period specific visual counts were
then added to those from the video camera.
Most spillways were underlayed with plywood ramps that were lined with white plastic
(Photo 7). Adult salmon silhouettes moving up or downstream were detectable to
observers against the white material. Removable weir panels covering access to the
ramps were used to block fish movement during non-flood events. Other spillway panels
were designed to allow release of water and pressure without allowing salmon to leap
over the weir, forcing fish to migrate upstream through the video chute (Photo 6).
There were also times when high water breached the weir unexpectedly, or in places that
were not planned spillways. In such cases, visual observations were made from shore for
a minimum of one hour to estimate whether fish were moving upstream through these
breaches. These breaches were then repaired, or fish were diverted to one of the planned
spillways.
Video was always the preferred method to estimate fish passage. Typically the video
remained operable even during flood events when the weir was overtopped. When water
was too turbid for video analysis, video chutes were closed off with plywood covers. All
counts of adult fish were then made visually as fish moved over the weir via ramps or
spillway panels.
All visual counts were recorded on standardized field forms. Data recorded included start
and stop times for surveys, locations that fish were counted, weir conditions (percentage
fish tight, etc.), and video conditions. An event log was kept to document any changes or
treatments made to the weirs for accommodating increased water flow or fish movement.
Logs were updated at a minimum of every three hours, or more frequently if conditions
required. Field form data were checked for accuracy then entered into a Microsoft® Excel
spreadsheet. Fish data during flood events were classified into six categories based on
weir conditions:
1. The video chute was open and the spillways were not; total fish passage was
estimated using video counts only.
2. Both the video chutes and the spillways were open; total fish passage was
estimated by adding video and visual counts.
3. The video chute was open but fish were escaping around it unobserved, through
breaches in the weir; fish passage was estimated from the video and taken as a
minimum estimate for that time period.
4. The video chute was open but the water was too turbid to count fish and fish
could not pass over the weir; no estimate of fish passage was made.
5. The video chute was closed and fish were being counted visually over the
spillway; total fish passage was estimated from visual counts only.
6. The video chute was closed and fish were moving upstream through spillways or
breaches, but could not be counted; no estimate of fish passage was made.
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Under scenarios 1, 2, and 5, it was possible to estimate full fish passage. Under Scenario
3, only minimum fish estimates could be made. Under scenarios 4 and 6, no estimates
could be made.
3.1.3 Data analysis
Catch per unit effort (CPUE)
Fishing effort at each sampling location was recorded as the amount of time that passed
between sampling events less any downtime due to gear modifications or damage. Catch
per unit effort (CPUE) was calculated as the catch divided by the amount of fishing
effort, reported in days. For example, a weir checked at 8 pm on July 1 would have a
total fishing effort of one day if it had been checked at 8 pm on June 30, but only 0.9 days
(22 hrs) of effort if it had been checked at 10 pm on June 30. Hours when the weirs or
RSTs were not fishing (due to maintenance, the RST drum being raised, or high water
events) were subtracted from the fishing effort.
Species diversity
Species diversity was calculated for each site (separately for each weir and combined for
the two RSTs), using species richness (r), Shannon-Wiener’s index of diversity (H’), and
Pielou’s (1966) evenness index (J’). Species diversity was calculated as:
H’ = [-Pi*(ln Pi)],
Where Pi is the proportion of species (i) in the community, and ln(Pi) is the natural log of
that proportion (Elliott and Hewitt 1997).
Species evenness was calculated as:
J’ = H’/H’max,
where H’ is the Shannon-Wiener index, and H’max (the maximum diversity) = ln (r), and r
= the total number of species (Elliott and Hewitt 1997).
3.2 Abundance of Coho and Chinook Salmon Smolts in the Chuit River Watershed
Abundance of coho and Chinook salmon smolts throughout the entire Chuit River
watershed was estimated using mark-recapture methods. Fish were marked in the
tributaries (at the weirs) and released below the weir to resume their downstream
migration. The population of fish moving downstream in the Chuit River was sampled at
sites approximately 12.7 to 29 km (7.9 to 18 mi) downstream of the tributary tagging
sites. The abundance estimate for the entire watershed population was a function of the
number of marked fish released at the weirs, and the ratio of marked to unmarked fish
sampled in the mainstem Chuit River.
To recapture fish in the mainstem river, two rotary screw traps (RSTs) were placed in the
Chuit River, about 1 km (0.6 mi) apart, and 3.5 to 4.0 km (2.1 to 2.6 mi) upstream of the
Chuit River mouth (Figure 2). The RSTs were created by EG Solutions of Corvallis,
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Oregon (http://home.teleport.com/~egs), and consisted of a drum with a 1.5-m (4.9-ft)
diameter mouth, resting between two 5.2 m (17 ft) long pontoons. Water entering the
drum mouth caused the drum to turn; fish swept into the trap were then funneled down
into a 0.61 x 0.61 m (2 x 2 ft) holding box at the downstream end of the RST (Photo 8).
Fish were removed from the holding box and sampled up to twice per day. The RSTs
were located where they could fish in the main current, at a target speed of six to eight
revolutions per minute. The optimal rotational rate was achieved by raising or lowering
the drum into the current or by moving the trap upstream or downstream. Traps were
fished alongside the bank, and tethered to the trees onshore with an anchor system
designed to keep the drum mouth facing perpendicular to the current (Photos 9 through
12).
In the mainstem river, fyke nets were fished concurrently with the upstream RST (RST1)
during the early season when catches in the RSTs were low, to determine if other habitat
types or stream locations held fish not captured by the RSTs. Minnow traps were also
fished in the area early in the season for the same reasons. Design and operation of the
fyke nets and minnow traps was described in section 3.1.1, above.
3.2.1 Marking of fish
Coho and Chinook salmon smolt abundance estimates were calculated for the Chuit River
using a two event mark-recapture method (Ricker 1975). Juvenile salmon captured at the
weirs that were ≥80 mm were marked with either a pelvic fin clip or temporary caudal fin
mark. These marks were alternated over time to allow for possible stratification by time
period to account for changes in capture efficiencies through the season. Marking
patterns were limited to the two mark types, which were cycled over alternate time
periods. Mark type was the same at all weirs during a given time period (i.e., we did not
stratify mark type by tributary). A minimum of 13 days separated like marks to allow
discrimination among marking strata. Fish were examined for marks (i.e., the 2nd
sampling event) at the RSTs in the Chuit River.
Release and recapture groups were apportioned into appropriate size classes based on the
site-specific daily length-frequency distributions of randomly measured fish from the
corresponding sample. The apportionment of these groups into size classes allowed for
examinations of size selection among the locations and gear types (i.e., weirs and RSTs).
All marked recaptures were measured to fork length.
3.2.2 Mark-recapture model selection and assumptions
Two mark-recapture models were considered for estimating the total abundance of coho
and Chinook salmon smolts in the Chuit River watershed. Model selection depended on
tests of equal probability of the recapture of marked fish through time. The first model
considered was a pooled Petersen estimate (PPE), with Chapman’s modification (Seber
1982), which was used if recapture probabilities in the RSTs were equal among time
strata. If recapture probabilities were not equal through time, a Darroch model (Darroch
1961) was used. In either case, fish were stratified into size classes post hoc based on
minimum and maximum lengths common to each site, and by any differences in size
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selectivity between the two types of gear (weirs and RSTs). Notation for variables in the
mark-recapture models were as follows:
n1 = marks released
n2 = fish checked for marks
m2 = recaptures in the second sample (n2)
u2 = number of fish without tags in the second sample (n2)
p1 = probability of capture at time 1 = m2/n2
p2 = probability of capture at time 2 = m2/n1
N = population abundance estimate
The Pooled Petersen estimate with Chapman’s bias correction (PPE; Seber 1982) was
calculated as
N=
(n1 + 1)(n2 + 1) − 1
(m2 + 1)
(1)
The assumptions required for this estimate to be unbiased were as follows (Seber 1982):
1. Closed population (i.e., no mortality or recruitment),
2. Either the probability of capture was constant across all individuals at the time of
capture (constant p1), or marked fish mixed uniformly with unmarked fish before
the recapture event, or the probability of capture was constant across all
individuals at the time of recapture (constant p2),
3. Marking did not affect catchability,
4. Tags were not lost, and
5. All tags were recognized and reported.
Assumption 1: closed population
Weirs were only placed on a subset of the tributaries that feed the Chuit River, and smolts
outmigrating from tributaries without weirs had no chance of being marked. This
addition to the population from outside of the marking pool has the same effect on the
population estimate as would recruitment, rendering the estimate germane to the
recapture site (the Chuit River) and not to the mark sites (streams 2002, 2003, and 2004).
We assumed no mortality due to the marking process and no appreciable natural
mortality between the marking and recapture sites. Smolt from this system migrate over
a short period of time (a few weeks or less) during a life history stage when mortality is
relatively low; thus, the potential for natural mortality between the weirs and the RSTs
was small. Mortality due to marking was thought to be negligible because fish were able
to be marked quickly with a minimal amount of handling (approximately 5 seconds per
fish to identify to species and mark), and were able to be released directly from the
holding box into the stream with no transfer needed. On the Nome River, the same
investigators have detected minimal latent mortality in coho salmon after tagging with
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coded wire tags, a more invasive process than used on the Chuit River (Williams et al.
2006).
Average travel time from the weirs to the RSTs was computed to help assess evidence of
injury manifested in the form of unusually slow migration time. Travel time from the
marking site (weirs) to the recovery site (RSTs) was modeled as a Poisson distribution,
which is typically used for count type data and can be described with one parameter. The
lag time (i.e., the one parameter = the expected value from the Poisson distribution)
between the number of fish released and the number recaptured at the RSTs, as well as
the recapture rate were adjusted (parameterized) to minimize the sum of square
differences between the number of recoveries observed and the number predicted based
on the Poisson travel time model.
Assumption 2: probability of capture constant or uniform mixing (or both)
Because we only placed weirs on a subset of streams, the probability of capture at the
marking site (p1) was not constant across all migrating smolt in the Chuit River (smolts
from tributaries without weirs had no chance of being marked). If smolt from tributaries
without weirs migrated at different times during the season then uniform mixing was
unlikely. Fluctuating water levels throughout the study period would likely change the
capture efficiencies of the RSTs at the recovery site, and p2 would not be constant for all
individuals. Any observed changes in capture probabilities, as well as lack of mixing,
through time were addressed by way of partial stratification (see Section 3.2.3, below).
Likewise, differences in capture probabilities across body sizes were corrected with sizestratified estimates. Rotary screw traps can be size selective, so we anticipated p2 might
be a function of fish size. The Kolmogorov-Smirnov two-sample test (KS test; Conover
1971) was used to detect if size selective sampling occurred during the second sampling
event. The cumulative length frequency distribution of all fish marked during the first
event (n1) was compared to that of marked fish recaptured during the second event (m2).
If the length distributions were significantly different (D statistic: the maximum absolute
difference between the cumulative distributions), then we used the size grouping
corresponding to the D statistic as the cut point for stratification. That is, separate
abundance estimates were developed for all fish smaller than or equal to the cut point and
fish greater than the cut point. Using the location of the D statistic as the cut point
ensures that the differences between two strata with respect to p2 were maximized, and in
so doing homogeneity of p2 within each size stratum was also achieved.
Assumption 3: equal catchability for marked and unmarked fish
Validating this assumption was not possible, but we considered it unlikely that marking
affected catchability at the recapture site because 1) the marks and fish handling were
chosen based in large part on strategies that would minimize effects on fish, and 2) the
use of different gear types at the mark and recapture sites would eliminate any learned
aversion to the gear by marked fish. Note that if fish from tributaries without weirs
experienced different p2 than fish from tributaries with weirs, the effect would be the
same as violating Assumption 3 because nearly all fish from tributaries with weirs were
marked. Differences in equal catchability due to differences in fish body size between
tributaries with and without weirs was tested using a Kolmogorov-Smirnov two-sample
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test of fish with marks (entirely from tributaries with weirs) and without marks (mostly
from tributaries without weirs).
Assumption 4: tags were not lost and marked fish survived to the recapture site
There was little chance of marked fish becoming unmarked between the marking and
recapture sites. The evaluation of marked fish travel times from the weir sites to the
RSTs was used to determine if there was enough time between sites for regeneration to
occur, thereby causing a loss of marks. Travel time of marked fish between sites was
estimated to help assess whether fish had a relatively long or short exposure to natural
mortality from sources such as predation. Fish marking and handling procedures were
designed to be less invasive than other marking studies that have caused little short-term
mortality.
Assumption 5: tags were recognized and reported
All fish captured in the RSTs were handled and inspected individually to keep the
probability of missing marks to a minimum. Furthermore, the number of fish handled
during individual site visits were low and the marks easily recognized.
3.2.3 Model selection
One of two models was chosen to provide a mark-recapture estimate for each size
stratum—the PPE with Chapman’s correction (Seber 1982) or the partially stratified
Petersen (i.e., the Darroch model [Darroch 1961]). Models were fit using the software
SPAS (Arnason et al. 1996) and thorough descriptions of both models are provided by
Schwarz and Taylor (1998). If Assumption 2 (above) was met then the PPE was chosen,
and all data throughout the season was pooled.
If Assumption 2 was not met, then the Darroch model (Darroch 1961) was used to
partially stratify the data into groups with similar capture probabilities (in this case
temporally). Initial temporal strata were preset based on the dates fin clips were altered;
however, further pooling to improve model fit occurred when recapture matrices were
uploaded into SPAS. Any pooling of rows was guided by similar p1 values estimated for
each cell, and columns were pooled based on similar p2 values across cells. The only
pooling requirement was that the matrix either be square (number of tagging strata =
number of recovery strata) or the number of tagging strata be greater than recovery strata
in order for the estimate to be applicable to the recapture site (Schwarz and Taylor 1998).
If a non-significant Chi-square test resulted from any of the following three tests (α =
0.05), then the PPE model was chosen.
Mixing test
Tagging stratum Recovered Not seen again
S1
n1- m2,S1,.
m2,S1,.
S2
n1- m2,S2,.
m2,S2,.
S3
m2,S3,.
n1- m2,S3,.
S4
m2,S4,.
n1- m2,S4,.
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Equal proportions test
R1
Marked m2,.,R1
Not marked u2,.,R1
Recovery strata
R2
R3
R4
m2,.,R2 m2,.,R3 m2,.,R4
u2,.,R2 u2,.,R3 u2,.,R4
Equal movement test
Tagging
stratum
S1
S2
S3
S4
R1
m2,S1,R1
m2,S2, R1
m2,S3, R1
m2,S4, R1
Recovery strata
R2
R3
m2,S1,R2
m2,S1,R3
m2,S2, R2 m2,S2, R3
m2,S3, R2 m2,S3, R3
m2,S4, R2 m2,S4, R3
R4
m2,S1,R4
m2,S2, R4
m2,S3, R4
m2,S4, R4
Not seen again
n1- m2,S1,.
n1- m2,S2,.
n1- m2,S3,.
n1- m2,S4,.
3.3 Fish Biological Characteristics
Fish captured in the tributaries and in the mainstem Chuit River were subsampled for a
variety of characteristics to understand their biology and life history, and to refine the
classifications of which Chinook and coho salmon should be considered smolts. The
following subsections apply to all locations where fish were sampled.
3.3.1 Sampling for length, weight, and age
Sampling sites were generally checked twice daily, or more frequently during times of
high water and heavy debris loads. At each check, fish were removed from the trap and
held in buckets for processing. All fish captured were identified to species and counted.
Separate counts were kept for juvenile and adult salmon. Species identifications were
made using several fish guides and keys, notably those by Phillips (1977), Pollard et al.
(1997), Morrow (1980), and Mecklenburg et al. (2002). Tissue samples from a few
juvenile coho and Chinook salmon were sent to the Gene Conservation Lab of the Alaska
Department of Fish and Game, Division of Commercial Fisheries, for confirmation of
species identification.
Subsamples of up to 30 fish of each species were collected randomly for length
measurements at each gear check. Species with forked tails were measured to fork length
(FL); species with rounded or truncate tails were measured to total length (TL). Adult
salmon were measured from mid eye to fork of tail (MEF). All lengths were recorded to
the nearest millimeter.
Scale samples, for ageing, were taken from randomly selected juvenile Chinook salmon,
juvenile coho salmon, rainbow trout, and Dolly Varden that were greater than 60 mm in
length. Coho and Chinook salmon scales were obtained twice per week and once per
week from Dolly Varden and rainbow trout. All of the scale sampled fish were collected
in the random length samples, using a pre-established catch calendar developed for each
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species. Scales were taken from the preferred location, posterior to the dorsal fin, above
the lateral line, following the methods of Jearld (1983), and archived on gum cards.
Completed scale cards were then sent to Birkenhead Scale Analysis (Lone Butte, B.C.)
for ageing.
Weights were taken from subsamples of the captured fish. All species caught were
weighed up to one time per week based on a pre-established catch calendar, with a target
sample size of 30 fish per species each week. The actual sample size varied depending
on the catch. Weights were recorded to the nearest 0.5 grams.
Fish subsampled for ages or weights were anesthetized in a 9:1 solution of clove oil
mixed with ethanol, diluted in water. Fish measured for length were anesthetized when
needed. Anesthetized fish were not released back into the stream until they were
vigorous and moved under their own power. Fish that were simply identified to species,
counted, and marked were not anesthetized unless needed (i.e. could not be handled
without anesthesia).
Coho and Chinook salmon were classified for smolt developmental condition to provide
estimates of the portion of the catch that was smolting. Juvenile coho and Chinook
salmon were examined for a silvery condition indicative of smoltification; as
smoltification begins, fish develop a silvery appearance, with the parr marks (dark
vertical lines on their body) becoming less prominent (Eales 1969).
3.3.2 Body condition
Relative weight (Wr) of select species was examined to provide an index of body
condition. Relative weight provides a comparison of the actual body condition of a fish
against a standard body condition. The standard body condition is the expected weight of
a fish in good condition at a given length and is generally composed of regional data from
multiple stream systems (Wege and Anderson 1978). However, there is little regional
smolt length-weight data available for the Chuit River, so regression input data were only
from the Chuit River sampling locations from 2008. By using only data from the Chuit
River, the Wr analysis is essentially acting as a standardization of the relative weight of
fish in the river in 2008, against which individual populations can be compared (e.g., fish
from Stream 2003 vs. the entire Chuit River watershed). As other regional streams are
studied in future years, the regressions can include regional length-weight data inputs and
Wr would become relative to a larger group of populations. Similarly, data from one
watershed can be compared among years to determine annual variation in body condition.
The Wr index is calculated as
Wr = (W/Ws) * 100,
Where W is individual fish weight and Ws is a length-specific standard weight predicted
from a weight-length regression developed to represent the body form of the species. A
relative weight value of 100 represents a healthy fish, and relative weights between 95
and 105 were considered to be in good condition. Fish with relative weights greater than
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105 were considered to be in better condition, and those below 95 were considered to be
in worse condition than fish in “good” condition (Pope and Kruse 2007).
Weights were recorded to the nearest 0.5 grams, effectively biasing the results for the
smallest fish caught. For example, a 30 mm and 40 mm long fish could both be recorded
to have the same weight, making the 30 mm fish appear in better condition. To eliminate
this bias, only fish >80 mm long were included in the analysis.
3.4 Environmental Sampling Methods
3.4.1 Water temperatures and depth – LGL Alaska
Stream temperatures were collected by project personnel near each of the sampling sites
with remote loggers programmed to record a temperature every 15 minutes (model
TempProV2, manufactured by Onset Computer Corporation, Bourne, MA). Stream
temperatures were also taken during fish sampling events with a hand-held bulb
thermometer. For this report, temperatures are reported as daily averages.
Water depth was recorded at each of the sample sites during sampling events. An
instream staff gauge at a fixed location in the stream was used for consistency in
measurement. Depth data were standardized (Neter et al. 1993) to have all of the streams
on the same scale for comparisons across all sampling locations.
3.4.2 Water temperatures and discharge – RTI
Temperature data were collected at numerous places in the watershed as part of separate
hydrological monitoring conducted by Riverside Technologies, Inc. (Ft. Collins, CO),
including all three study tributaries and in the mainstem Chuit River (RTI 2007).
Gauging stations were visited monthly by RTI personnel and stream temperatures were
measured to check instrument calibration (RTI 2007).
Temperature data were collected using Campbell Scientific CR10 data loggers.
Discharge data were collected using Marsh-McBirney current meters to measure stream
velocities. Water depth and mean velocities were measured at subsections of the stream
using the midsection method. The mean stream velocities and the cross-sectional areas of
each subsection were multiplied and then added together to calculate stream discharge. A
full description of the hydrology methods is found in the hydrology baseline report by
RTI (2007).
3.4.3 Precipitation - McVehil-Monnett
Precipitation data were collected by McVehil-Monnett from a weather gauging station on
Stream 2004 within the mining area. The station is located at an elevation of 206 m (677
ft; McVehil-Monnett 2006) and is roughly 3 km (1.9 mi) upstream from the confluence
with the Chuit River. Daily precipitation data were provided in inches and centimeters.
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3.5 Data Entry
All data were recorded on standard datasheets developed for the project. After each
sampling event, datasheets were checked for completeness and accuracy by a second
person not involved in the recording of the data, and then entered into an online database
managed by Axiom Consulting and Design (Anchorage, AK; www.axiomdms.com).
Database entries were then hand-checked against the original field datasheets to ensure
accuracy. Digital copies of the original datasheets were maintained on the LGL server as
a backup. Data were organized and summarized using Microsoft® Access and
Microsoft® Excel.
4.0 Results
4.1 Sampling Effort
4.1.1 Tributaries
Fish were sampled daily on the smolt weirs from May through September, 2008, with
some variation in the range of dates among the three study tributaries (Table 2). Fish
sampling provided a complete or nearly complete census of the downstream migrating
fish.
Partial weirs were installed in Stream 2002 on May 3 and Stream 2003 on May 4 to
subsample the streams for moving fish (Figure 5). The partial weirs covered
approximately 75% of the width of each stream, including the part of the stream with the
highest flow (Photo 13). The weir panels altered the flow dynamics, however, causing
the main current to migrate. Thus, approximately 33% to 50% of the stream flow was
effectively captured by the partial weirs. Few fish were caught in the partial weirs in
either stream during this early period in May. Although fish could have been moving
around the weir, the low number of fish caught led us to conclude few fish were
migrating at this time. On May 12, the weir in Stream 2002 was removed due to high
water and a fyke net was installed downstream to continue to sample for fish. The partial
weir in Stream 2003 was kept in place until it was replaced by the full weir on May 27
(Figure 5). Full weirs, covering 100% of the streams, were completed on all three of the
study streams by early June. Weirs were fishing effectively for most of June, July, and
August. Repairs and minor modifications were common and adjustments were needed to
adapt to varying hydrological conditions. On several occasions with high water, the
weirs were unable to seal off the entire stream (Figure 5).
The weir in Stream 2002 was fished for 111 of the available 118 days between May 3 and
September 19. From May 3 through May 12 a partial weir was in place then removed
due to high water. A full weir was installed on June 4 (Figure 5; Photos 14 and 15). On
May 13 a fyke net was set-up and fished for the days between when the partial weir was
removed and the full weir was installed. Eleven minnow traps were used for two to three
days, starting on May 23.
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The partial weir in Stream 2003 was installed on May 4 and was extended to a full weir
on May 27, fishing through September 30 (Photos 16 and 17). The weir was remodeled
in June to adjust to lower water levels. Overall, the weir was fished for 147 of the 150
days elapsed between May 4 and September 30 (Figure 5).
A full weir in Stream 2004 began fishing on June 8 and fished 96 of the possible 115
days through September 30 (Photos 18 and 19). The fyke net in Stream 200401 was
established on June 29 and fished through July 17, from July 19 through July 27, and
again from July 29 through September 3, for a total of 65 days (Figure 5).
Heavy debris loads or flood events caused water to overtop the weir panels at times. After
the first major flood event in late July, weirs were adjusted and modified to withstand the
increased discharge expected in September. Holes in the weir panels were occasionally
caused by woody debris or bears, and panels shifted under water pressure. Modifications
were made to prevent fish mortalities during high flows when the water overtopped the
panels. In some cases, holding boxes were removed from the weir to prevent fish
mortality and relieve water pressure.
4.1.2 Chuit River
The Chuit River was sampled daily from May through September, using two rotary screw
traps (RSTs; Table 2). The RSTs were installed in May and both sites fished
continuously for most of the season with only a few minor stoppages from debris jams,
gear malfunctions, or to modify the trap placement. On several days in August the RSTs
were only fished for partial days instead of full days. Also, during high water events, the
RST drums were raised to prevent debris from being lodged and damaging the RST.
RST1, located upstream of the bridge, was installed on May 12, fished through
September 13, and was removed on September 25 (Figure 5; Photos 9 and 10). RST1
fished for 123 of the eligible 125 days. A fyke net was placed downstream of RST1 on
May 26 and fished for 12 days, then removed. The fyke net was re-established on July 2
and fished for 16 days. Six minnow traps were also deployed near the fyke net and in the
Chuit River, from May 25 to 29.
RST2, located downstream of the bridge, began fishing on May 14, fished through
September 3, and was removed on September 25 (Figure 5; Photos 11 and 12). RST2
fished for 111 of the available 113 days. Both RSTs were repositioned throughout the
season as water levels changed to capture more flow.
4.1.3 Gear downtime
Times when weirs and rotary screw traps were not fishing were considered down time.
During downtime, fish were not being captured in holding boxes and therefore no
sampling occurred. Downtime was determined by adding the total numbers of hours the
gear was not fishing for each site (Figure 6; Appendix A). At the weirs, downtime was
associated with high water events. Liveboxes were removed to prevent fish mortalities
and to relieve water pressure on of the weir. At the RSTs downtime occurred when the
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cones were raised for cleaning, or to prevent damage caused by large woody debris. In
most cases, downtime was associated with high water events.
4.2 Fish Movement and Abundance in Tributaries – Fish Moving Downstream
4.2.1 Fish abundance and species composition
In total, 78,308 fish were captured moving downstream from all sampling sites combined
(Tables 3 and 4; Figure 7). The weirs caught 74% of the total catch (Table 3), with 30%,
25%, and 20% of the total catch coming from the weirs in streams 2004, 2003, and 2002,
respectively. By far the most common species captured was juvenile coho salmon.
Juvenile coho salmon made up 87% of the total catch composition and ranged from
94−98% of the catches at the weirs. At all three sites, the majority of juvenile coho
salmon larger than 90 mm were caught in June and the majority of juveniles smaller than
90 mm were caught in July. Chinook salmon were caught in greater numbers in the
Chuit River than in the tributaries, making up 20% of the catch, although coho salmon
still dominated and were 65% of the Chuit River catch (Table 3). The one location where
catches of another species was greater than the catch of juvenile coho salmon was Stream
200401. The fyke net placed in this location caught a large number of age-0 rainbow
trout that made up 55% of the total catch. Juvenile coho salmon were 43% of the catch.
In total, 14,548 fish were captured moving downstream in the Chuit River (Table 4).
Unadjusted for effort, the rotary screw traps caught 19% of the combined catch from all
sites. The most common species captured was juvenile coho salmon, which made up
64% of the catch (Table 3). Chinook salmon were caught in greater numbers in the Chuit
River than in the streams, making up 20% of the RST catch. Juvenile lamprey, rainbow
trout, coastrange sculpin, Arctic lamprey, slimy sculpin, and Dolly Varden represented
15% of the catch combined (Table 3).
In streams 2002, 2003, and 2004 combined, thirteen fish species and two groups not
identified to species (sculpin, lamprey) were captured over the course of the study (all
gear types combined). Juvenile coho salmon made up the greatest proportion of the total
catch. Arctic lamprey, Chinook salmon (adult and juvenile), coho salmon (adult and
juvenile), coastrange sculpin, Dolly Varden, rainbow trout, and slimy sculpin were
caught at all three of the study tributaries.
Eleven species and two species groups were caught in Stream 2002. Seven fish were
unidentified. Pacific lamprey, ninespine stickleback, and threespine stickleback were
captured only in Stream 2002 and not seen in the other two tributaries (Table 4).
Eight species and two species groups were captured at the weir in Stream 2003. One fish
was not identified to species (Table 4).
Nine species and two species groups were caught in Stream 2004. Chum and sockeye
salmon were caught in Stream 2004 and were not captured in the other two study
tributaries (Table 4).
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Stream 2002 had slightly higher species richness, diversity, and evenness than streams
2003 and 2004. Species richness was lower in Stream 2003 than in Stream 2004, but
species evenness was higher (Table 5).
Six species and one species group of fish (sculpin) were caught in the fyke net in Stream
200401, the tributary entering Stream 2004. Species richness was greater in the
tributaries than in Stream 200401 however, species diversity was greater in Stream
200401. Species evenness was greatest in Stream 200401 as compared to the three study
tributaries and Chuit River (Table 5).
Thirteen different species and two groups not identified to species (sculpin, lamprey)
were captured in the rotary screw traps, fyke nets, and minnow traps in the Chuit River.
Juvenile coho salmon made up the greatest proportion of the total catch (Table 3). All of
the fish caught in the Chuit River were also caught in at least one of the tributaries (Table
4). Species richness, evenness, and diversity were greatest in the Chuit River (Table 5).
When all sites and gear types (including RSTs) were combined, overall species richness
in the Chuit River drainage was 13 species and overall diversity (H’) was 0.43 (Table 5).
Video detections of fish moving downstream
Five different species and three groups not identified to species (sculpin, lamprey, and
some adult salmon) were observed through the video chute in all three streams (Tables 6
through 8). Most detections were in Stream 2002 because this stream was the only one
with a video passage chute installed during peak smolt migration. Dolly Varden, rainbow
trout, Chinook salmon, coho salmon, and pink salmon were observed in all three streams;
adult sockeye salmon were also detected in Stream 2004 (Table 8). Adult salmon
movements usually occurred after high water events, and were thought to be a minor
redistribution of fish after a major upstream movement event. Juvenile salmon were
separated into three size groups (<45 mm, 46−100 mm, and >100 mm), and the species
apportionment was based on the species composition of juvenile salmon captured that
day in the holding box, where fish identification was most reliable. The number of
salmon smolts moving downstream through the video chutes were 6,464 on Stream 2002,
396 on Stream 2003, and 856 on Stream 2004 (Tables 6 through 8). Based on the
apportionment, the video counts contributed 6,367 coho salmon smolts in Stream 2002,
396 coho salmon smolts in Stream 2003, and 856 coho salmon smolts in Stream 2004.
Adult Chinook, coho, and pink salmon were also seen moving downstream in streams
2002 and 2003.
The majority of coho salmon smolts were detected in June as discharge decreased and
water temperature increased (Figures 8 and 9). Some smolts were also seen passing
through the video chute during or after high water events. Adult salmon traveled
upstream during rain events and some went downstream as the flow regime lowered. In
Stream 2002, coho salmon smolts were detected on the day the video was first installed
(June 8; Appendix B). Detections increased through the middle of June and peaked on
June 27; thereafter, detections decreased to only a few fish by the first week of July.
Smolt-sized coho salmon were detected through August 4, although most of these fish
may have no longer been smolting.
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After installation of the video system in streams 2003 and 2004, run timing of coho
salmon smolts followed a similar pattern to that seen in Stream 2002, but about a week
later. Detections at both sites increased until a peak centered on July 3 and 4 with
numbers dropping off to a few fish by the second week in July (Appendices C and D). A
small spike in detections occurred in early August at Stream 2003 that was not seen at
streams 2002 or 2004. Smolt-sized coho salmon were detected as late as the first week in
September at both streams 2003 and 2004.
Only a few small rainbow trout (45−100 mm) were noted on the video at Stream 2002,
most occurring from mid June to early July. Rainbow trout >100 mm at Stream 2002
were most numerous when the video was first installed from June 8 through June 20,
followed by low numbers for most of July until a peak at the end of July (Figure 10).
Numbers decreased again in early August. Another smaller peak in activity occurred for
about a week beginning in early September (Figure 10).
Small rainbow trout (45−100 mm) detected on the video at Stream 2003 were most
concentrated from video installation on June 30 until mid July. Rainbow trout >100 mm
at Stream 2003 were seen most frequently in late July until mid August with few
individuals detected in September (Figure 10).
In the video in Stream 2004, rainbow trout 45−100 mm were seen only in the month of
July with a peak in activity in mid July. Rainbow trout >100 mm were seen throughout
the study period with the largest peak in activity the last two weeks in July (Figure 10).
Another smaller peak in detections occurred in mid September, dropping off quickly to
only a few fish for the rest of the month.
Video detections of Dolly Varden char in the 45−100 mm size class were few to absent at
all sites, so they were lumped in with fish >100 mm in these descriptions. In Stream
2002 Dolly Varden trout were first seen on July 23 and peaked in number in the first
week in August (Figure 11). A second, smaller peak occurred on September 3. Dolly
Varden in Stream 2003 showed a similarly timed first peak but followed by constant low
numbers for the rest of the study period. Stream 2004 had a similar trend pattern of Dolly
Varden trout occurrence to Stream 2002 except the second peak in early September was
greater than one in early August.
Video images of small juvenile salmon (<100 mm) at streams 2002 and 2004 showed
these fish to be present throughout the study period (July-September) in small numbers
with no noticeable trends. Juvenile salmon <45 mm were only found in large numbers in
Stream 2003, nearly exclusively in the month of July, with a peak concentration from
July 12 through 14, and then were absent after the first week in August. Juvenile salmon
in the 45−100 mm size class at Stream 2003 followed a similar trend but also showed a
second smaller peak concentration in early August. Neither size class was seen at Stream
2003 in September.
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4.2.2 Run timing and biological characteristics of juvenile coho salmon
In all three tributaries, CPUE peaked for coho salmon smolts (≥90 mm; Photo 20) as
water levels dropped and water temperatures increased. After this peak in CPUE, the
catch was composed of younger, smaller coho salmon that gradually increased in size
throughout the remainder of the season. Coho salmon captured in June and early July
were predominately over 90 mm in length. After mid July, captured coho were primarily
90 mm or less in length. The highest catches of pre-smolt coho salmon (<90 mm) were
in late July, associated with a high water event (Figure 8). CPUE of juvenile coho salmon
increased as discharge decreased and water temperatures increased (Figures 8 and 9).
Increases in the CPUE for juvenile coho salmon was also associated with increased
discharge following rain events (Figure 8)
The largest juvenile coho salmon were caught in mid to late June and in early July, with
age-2+ accounting for the bulk of the catches. After the peak of the run, coho salmon age
and body size decreased. The distribution of lengths by age class overlapped during
some time periods. Age and length analyses showed similar patterns among all the study
tributaries. The age and length analyses in the Chuit River were similar but age-2+ fish
were seen through mid August. Starting in mid July, age-1 coho salmon were a
substantial proportion of the coho salmon that were moving downstream. The smallest
size class were age-0 and were captured primarily after mid June (Figures 12 through 15).
Length measurements were collected from 25,098 fish, with 17,248 (69%) of the length
measurements taken from juvenile coho salmon (Table 9). Weight measurements were
collected from 3,625 fish throughout the season. Juvenile coho salmon averaged 71 mm
(27-271 mm). Length of coho salmon peaked in June. Mean weight of juvenile coho
salmon was 5.6 g (0.5−77.0 g; Table 9). The largest number of juvenile coho salmon
were caught in Stream 2004 (Table 4) and consisted primarily of fish less than 80 mm
(Figure 16). Relative weight (Wr) of coho salmon differed among sites (Figure 17).
Stream 2002
Juvenile coho salmon were captured in Stream 2002, as soon as the full weir was
installed on June 4. Catch per unit effort (CPUE) for coho salmon smolts (≥90 mm)
peaked on June 6 (229 fish/day), then remained relatively constant through June 29 (206
fish/day). The CPUE then quickly decreased and the last coho salmon smolt was caught
on August 20 (Figure 18). In total, 2,512 coho salmon smolts were caught at the weir and
another 6,367 were estimated to have moved through the video chute (Table 10).
The CPUE for juvenile coho salmon <90 mm caught in Stream 2002 remained fairly
constant for the month of June, not exceeding 55 fish/day. The CPUE gradually
increased and peaked on July 18 at 1,775 fish/day, then fluctuated from 43 to 942
fish/day until the end of July. On July 27 the CPUE was 1,489 fish/day, and then steadily
decreased, with pulses of fish moving downstream after rain events (Figure 8). Overall,
14,897 juvenile coho salmon (smolts and pre-smolts) were captured throughout the study
period (Table 4).
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The relative weights of juvenile coho salmon in Stream 2002 were lower than expected in
May, but fish were still considered in healthy condition. Throughout June, body
condition was within the standard weight range (95−105). Relative weights fluctuated
the most (by week) in July, when both high and low relative weights were observed. In
early August relative weights were high, and then dropped below 100 before increasing
(Figure 19).
Stream 2003
The majority of coho salmon smolts (≥90 mm) were captured in June in Stream 2003,
with the CPUE peaking on June 20, 827 fish/day. The CPUE then decreased and the last
fish in this size class was caught on July 24 (Figure 18). In total, 7,394 coho salmon
smolts were caught at the weir and another 396 were estimated to have moved through
the video chute (Table 10).
The CPUE for coho salmon pre-smolts (<90 mm) in Stream 2003 peaked in late July.
The CPUE fluctuated in June and leveled off in early July before peaking on July 18 with
2,667 fish/day (Figure 18). Fish numbers then decreased. In total, 18,698 fish (smolts
and pre-smolts) were captured in Stream 2003 (Table 4).
The relative weights of juvenile coho salmon in Stream 2003 were healthy through May
and most of June. In the end of June and early July body condition decreased. In mid
July body condition again increased and met the expected level. By late July and through
August relative weights were fairly level ranging from just below the expected weight to
a slightly high relative weight (Figure 19).
Stream 2004
Juvenile coho salmon were caught at Stream 2004 as soon as the weir was installed on
June 8. The CPUE for coho salmon smolts (≥90 mm) increased after the first two days,
from 2 to 80 fish/day. Smolt CPUE peaked on June 22 (537 fish/day) and then decreased
(Figure 17). In total, 4,085 coho salmon smolts were captured at the weir in Stream 2004
and another 856 were estimated to have moved downstream through the video chute
(Table 10).
Stream 2004 had the largest run of pre-smolt coho salmon (<90 mm) of the three study
tributaries. The CPUE fluctuated throughout June and early July, peaking at 1,902
fish/day on July 27. On July 24 and 28 the CPUE was approximately 1,380 fish/day.
The CPUE then decreased and rose again on August 26 with a CPUE of 1,279 fish/day,
then decreased (Figure 18). In total, 22,682 juvenile coho salmon (smolts and presmolts) were caught in Stream 2004 (Table 4).
The relative weights of juvenile coho salmon in Stream 2004 demonstrated the least
amount of variance among three streams. Body condition met the weight expectations in
June. The relative weights were lowest in mid July and then increased, leveling off in
late July. For most of the season, relative weights were at or just below the expected
weights (Figure 19).
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Stream 200401
The fyke net was fished for a total of 65 days. Juvenile coho salmon represented 43% of
the catch (Table 3). Few juvenile coho salmon ≥90 mm were caught in Stream 200401.
CPUE for juvenile coho salmon ≥90 mm peaked on July 4 at 4 fish/day. CPUE for
juvenile coho salmon <90 mm was highest from mid to late July. The CPUE for juvenile
coho salmon peaked on July 17 at 308 fish/day (Figure 19). The mean length (fork
length) for measured juvenile coho salmon was 57.6 mm. In total, 2,212 juvenile coho
salmon were caught in Stream 200401 (Table 4).
Chuit River
The majority of coho salmon ≥90 mm were caught in late June through mid July with the
highest CPUE of 23.4 fish/day on July 3. However, the CPUE peaked on September 6
with 39.1 fish/day after a high water event. Most of juvenile coho salmon smaller than
90 mm were caught after high water events in late July and in early September. CPUE
for juvenile coho salmon <90 mm was on September 4 at 936.4 fish/day (Figure 18).
Only one rotary screw trap was operational after September 3.
In general, the relative weights for juvenile coho salmon were higher in the Chuit River
than in the tributaries. Relative weights for juvenile coho salmon in the Chuit River were
lowest early in the season. By June the relative weight met or exceeded the range of
good body condition (95−105; Figure 19). Relative weight was lowest in mid July, then
slowly increased.
4.2.3 Run timing and biological characteristics of non-coho salmon species
Daily CPUE was computed for two size classes for each of five species of fish. Water
temperatures and discharge were compared to the daily CPUEs and described for each
species. These fives species and size classes were:
1. Coho salmon – juvenile salmon <90 mm and salmon smolts ≥90 mm (described
above in section 4.2.2),
2. Arctic lamprey – fish <175 mm and fish ≥175 mm,
3. Chinook salmon – juvenile salmon <65 mm and salmon smolts ≥65 mm,
4. Dolly Varden – juveniles <100 mm and adults ≥100 mm, and
5. Rainbow trout – juveniles <100 mm and adults ≥100 mm.
In addition to juvenile coho salmon (described above in section 4.2.2), relative weights
(Wr) were calculated for juvenile Chinook salmon, Dolly Varden, and rainbow trout to
provide an index of body condition. The relative weights for all four species groups
fluctuated throughout the season. Relative weights were in the lowest category for many
individual fish (Figure 20).
Arctic lamprey
Adult Arctic lamprey were caught in all three tributaries and in the Chuit River. Adult
Arctic lamprey represented 2% of the fish caught in Stream 2002, 1% of the fish in
Stream 2003, and 2% in the Chuit River; very few were captured in Stream 2004 (Table
3). Only adult lamprey could be identified to species (Pacific or Arctic); juveniles that
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had not yet undergone metamorphosis were classified as ammocoetes of unknown
species.
In streams 2002 and 2003, CPUE of adult Arctic lamprey was highest in June. In Stream
2002, CPUE of the large size class of Arctic lamprey (≥175 mm) peaked on June 14 at
16.7 fish/day and on June 16 at 3.1 fish/day in Stream 2003. CPUE for the small size
class (<175 mm) peaked on June 7 at 19.4 fish/day in Stream 2002 and on June 14 at 24.6
fish/day in Stream 2003. In Stream 2004, where very few Arctic lamprey were captured,
CPUE peaked on August 21 at 2.1 fish/day (Figure 21). No Arctic lamprey were caught
in Stream 200401.
CPUE was highest in the Chuit River in late June through early August (Figure 21).
CPUE peaked for the largest size class on August 10 at 2 fish/day and for the smallest
size class on July 1 at 6.1 fish/day (Figure 21). CPUE of adult Arctic lamprey increased
as discharge decreased and water temperatures increased (Figures 22 and 23). CPUE also
increased in the Chuit River during high water events in early September.
Arctic lamprey lengths ranged from 55−505 mm with a mean length of 151 mm.
Lamprey lengths were relatively consistent throughout the season, with a slight increase
in overall length in August and September (Table 11; Figure 24). Mean weight was 11.0
g (range 2.0−361.0 g; Table 9).
Chinook salmon adult
Thirty four adult Chinook salmon were caught at the weirs and rotary screw traps. Adult
Chinook salmon included both normal sized adults and smaller jack Chinook salmon
(Figure 25). Many adult Chinook salmon were jacks. Salmon were captured from mid
July through mid August. The mean length (mid-eye to fork) of adult Chinook salmon
was 454 mm (range 280−855 mm; Table 9). Weights were not taken on adult salmon.
Chinook salmon juveniles
Chinook salmon juveniles were caught at all sites, but predominately in the Chuit River.
In total, 3,237 juvenile Chinook salmon were caught in the Chuit River drainage (Table
4). Juvenile Chinook salmon made up 20% of the catch in the Chuit River and 1% of the
catch in Stream 2002 (Table 3).
Within the tributaries the greatest number of the juvenile Chinook salmon were caught in
Stream 2002, very few were captured in streams 2003 and 2004. Most of the Chinook
salmon moved downstream from late May through mid July. Very few were caught after
July 14. CPUE for Chinook salmon juveniles ≥65 mm peaked on June 29 at 31 fish/day
in Stream 2002. In Stream 2003 the CPUE peaked on June 23 at 4.2 fish/day and 8.1
fish/day on June 13 in Stream 2004. The highest CPUE for juvenile Chinook salmon <65
mm among all three streams was in Stream 2002 at 1.1 fish/day (July 4; Figure 26).
Chinook salmon moved downstream throughout the course of the season in the Chuit
River. The majority of juvenile Chinook salmon were caught from late May through
June. CPUE for juvenile salmon ≥65 mm peaked on the Chuit River on June 18 at 26.2
fish/day. CPUE for juvenile salmon <65 mm peaked at 39 fish/day on June 13 (Figure
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26). At all sites, the CPUE for juvenile Chinook salmon increased as water levels
decreased and temperatures increased. The CPUE also increased in association with high
water events after heavy and persistent rainfall.
Chinook salmon juveniles averaged 65 mm in length (fork length) and ranged from
25−31 mm (Table 9. Lengths increased during the season (Figure 27). Mean weight was
4.7 g (0.5−111.0 g; Table 9).
In general, the relative weight (Wr) for Chinook salmon remained fairly constant
throughout the season. Relative weights were 90 or above with the exception of one
outlying value in August at 83 (Figure 19). Few Chinook salmon were caught on the
tributaries; those that were had relative weights higher than 95. Relative weights for
Chinook salmon in the Chuit River were below the expected weight, from May through
mid June. By the end of June the relative weights had increased and either met or
exceeded the expected standard weight (Figure 19).
Chum salmon (juvenile)
In total, six juvenile chum salmon were caught within the study area. One chum salmon
was caught at the weir in Stream 2004 during the month of June. Five chum salmon were
caught at the RSTs from late May through mid July. Fish lengths ranged from 24−94
mm (Figure 28), with an average of 44 mm (Table 9). No adult chum salmon were
captured. No weights were taken.
Coastrange sculpin
Coastrange sculpins were caught in all three tributaries and the Chuit River. Most of the
coastrange sculpins were captured in the Chuit River, where they represented 3% of the
catch (Table 3). The largest number of coastrange sculpins caught in the tributaries was
at Stream 2004 (a total of 62 fish; Table 4). Coastrange sculpin were observed
throughout the season in the tributaries and most fish were caught in July and August. In
the Chuit River, most sculpin were caught in the first half of September. However, many
were also moving downstream in July and August. The mean length of coastrange
sculpin was 65 mm (20−114 mm; Figure 29) and mean weight was 4.0 g (0.5−19.5 g;
Table 9).
Coho salmon adult
In total, 13 adult coho salmon were caught at all sampling sites, from mid July through
September (Table 4). Adult coho salmon were present in streams 2002 and 2003 in mid
to late July. A few were caught in the Chuit River in August. Adult coho salmon were
captured at all sites, excluding Stream 2002, in September. Water levels increased in
September due to heavy and persistent rainfall. Adult coho salmon migrated upstream as
discharge increased, some of the adult salmon then moved back downstream. Adult coho
salmon averaged 496 mm (359−590 mm; Table 9). Weights were not taken.
Dolly Varden
Dolly Varden were caught in all three streams and the Chuit River over the course of the
study. In total, 455 Dolly Varden were caught at all sampling sites and represented 1% of
the fish captured in Stream 2003, Stream 2004, and Chuit River (Tables 3 and 4).
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Dolly Varden CPUE for fish ≥100 mm was the highest in late May and early September,
and often associated with high water (Figure 30). The largest number of Dolly Varden
were caught in streams 2003 and 2004. CPUE for Dolly Varden ≥100 mm was 26.3
fish/day in Stream 2003 (May 30), and 27.3 fish/day in Stream 2004 (August 27). CPUE
for Dolly Varden ≥100 mm in Stream 2002 was on September 4 at 11.4 fish/day (Figure
31). CPUE was highest for Dolly Varden <100 mm in Stream 2004 and peaked on June
19 at 3.1 fish/day. CPUE did not exceed 1.1 fish/day for Dolly Varden <100 mm in
streams 2002 and 2003 (Figure 31). Overall, CPUE increased in the early summer as
water levels decreased and temperatures increased (Figures 30 and 32).
Dolly Varden ≥100 mm were caught in the Chuit River throughout the season, but very
few fish were captured in July. The highest numbers of fish ≥100 mm were observed in
May and September. CPUE for Dolly Varden ≥100 mm peaked on September 13 at 7.1
fish/day. In the Chuit River the majority of Dolly Varden <100 mm were observed from
mid June through early July and a few were seen in September. The CPUE for fish <100
mm peaked on September 8 at 2.9 fish/day (Figure 31)
The majority of Dolly Varden caught at all sampling sites were ≥100 mm in length
(Figure 33). Mean length of Dolly Varden was 155 mm (36−350 mm) and mean weight
was 51.8 g (2.0−462.0 g; Table 9). These weights did not necessarily correspond with
the minimum and maximum lengths.
Relative weights of Dolly Varden on all three streams were within the range of good
condition (95−105; Figure 19). Relative weights for Dolly Varden observed on the Chuit
River met or exceeded the expected weight from May through early August. From mid
August through mid September relative weights were lower than the standard weight
(Figure 19). Body condition of Dolly Varden was difficult to interpret, presumably
because juvenile and adult data are compared together.
Lamprey spp. adult
Lamprey were not identified to species before June 10, accounting for 21 fish from
streams 2002 and 2003. The mean length of these fish was 129 mm (115−150 mm). The
mean weight of unidentified lamprey was 3.2 g (1.0−6.0 g; Table 9). Based on run
timing and size, the 21 fish were probably Arctic lamprey.
Lamprey spp. juvenile
Juvenile lamprey are those fish that have not yet undergone metamorphosis, and are
known as ammocoetes. Ammocoetes were not differentiated to species, although all
were presumably either Pacific or Arctic lamprey, based on adult lamprey captures.
Ammocoetes were seen on all three streams and in the Chuit River (Table 4). Lamprey
ammocoetes represented 1% of the fish caught in Stream 2002 and 5% of the catch in the
Chuit River (Table 3). Juvenile lamprey were caught from mid May through early
September. Total catch of ammocoetes was highest in June. Fish size ranged from
17−222 mm with a mean length of 113 mm. The mean weight of lamprey ammocoetes
was 2.3 g (0.5−6.0 g), not necessarily including the 222 mm fish (Table 9).
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Ninespine stickleback
Two ninespine sticklebacks were caught in Stream 2002 and seventeen ninespine
sticklebacks were caught in the Chuit River (Table 4). Ninespine stickleback were
present from May to September, though less common in June through August. In the
Chuit River, sticklebacks were caught in all months except July. In Stream 2002,
ninespine sticklebacks were caught only in September. The mean length of ninespine
stickleback was 43 mm (29−60 mm; Figure 34). The mean weight was 1.4 g (0.5−3.5 g;
Table 9).
Pacific lamprey
Six Pacific lamprey were captured during the first half of July in Stream 2002 (Photo 21).
Two Pacific lamprey were caught at the end of July and early August in the Chuit River
(Table 4). The mean length was 430 mm (145−530 mm; Table 9; Figure 24).
Only one weight was taken on a Pacific lamprey, a 443 mm fish that weighed 205 g.
Pink salmon adult
Eighteen pink salmon were captured in late July and August in streams 2002 and 2003.
Eighteen pink salmon were also caught in the Chuit River in August. MEF lengths of the
salmon ranged from 265−524 mm with a mean of 387 mm (Table 9). No weights were
taken on any adult pink salmon.
Pink salmon juvenile
With the exception of one fish, all juvenile pink salmon were caught in the RSTs from
mid May through mid July. One other juvenile pink salmon was captured in the fyke net
in Stream 2002 at the end of May. The mean length of pink salmon juveniles was 34 mm
(26−38 mm; Table 9; Figure 28) and the mean weight was 0.6 g (0.5−1.0 g).
Rainbow trout
Rainbow trout were captured in the study tributaries and in the Chuit River throughout
the season. In total, 3,616 rainbow trout were caught at all sampling sites combined.
Rainbow trout represented 3% of catch on the Chuit River and 1% of the catch in Stream
2004. The largest proportion of rainbow trout were caught at the fyke net in Stream
200401. Rainbow trout represented 55% of the total catch at Stream 200401 (Table 3).
In Stream 2002, CPUE for rainbow trout ≥100 mm peaked in late July and then decreased
before it peaked again on September 4. CPUE for fish <100 mm was highest in early
June then decreased (Figure 35).
Rainbow trout were captured in Stream 2003 from late May through August. Most of
these fish were ≥100 mm, and the CPUE was fairly steady. Fish <100 mm were caught
in August (Figure 35).
In Stream 2004, rainbow trout were observed from June through September. CPUE for
fish ≥100 mm was high in mid June, decreased, and then peaked in late June. CPUE for
fish <100 mm increased through June and early July and peaked on July 22 before
decreasing (Figure 35). Rainbow trout lengths (fork length) ranged from 20−470 mm
(Table 9).
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In Stream 200401, rainbow trout dominated the catch. The vast majority of the rainbow
trout were <100 mm in length. Rainbow trout ≥100 mm were seen on two days at the
end of July. CPUE for larger fish was 12.2 fish/day on July 29. A few fish <100 mm
were seen at the end of June to early July; however the majority of the fish were caught at
the end of July through early August. The CPUE for rainbow trout <100 mm was 640.4
fish/day on July 27. Sizes ranged from 20−143 mm, with an average length of 35 mm.
The mean length (fork length) of the trout measured was 30.5 mm.
Rainbow trout were captured from mid May through September in the Chuit River. From
mid June through mid August the CPUE stayed relatively constant. The CPUE increased
in late August. The CPUE for fish ≥100 mm and <100 mm peaked in early September.
The CPUE for rainbow trout ≥100 mm was 7.1 fish/day on September 4. The CPUE for
fish <100 mm was 15.5 on September 6 (Figure 35). CPUE increased as water levels
decreased and water temperatures increased (Figures 36 and 37).
The mean length of rainbow trout was 73 mm (20−470 mm; Figure 33). Mean length
was largest in May and decreased through August, then increased again in September
(Table 11). Mean weight of rainbow trout was 31.0 g (0.5−691.0 g). Catch of rainbow
trout <100 mm peaked in July. Catches of rainbow trout ≥100 mm were highest in mid
June and late August. Rainbow trout of both size classes were present throughout the
whole season.
In the beginning of the season, relative weights of most rainbow trout at all sites were in
the lowest category (<95). Over the course of the season, relative weights increased
slowly, even exceeding standard expected values (>105; Figure 19). Body condition of
rainbow trout fluctuated throughout the season. As with Dolly Varden, rainbow trout
relative weights were difficult to interpret, presumably because juvenile and adult data
were analyzed together.
Sculpin spp.
Unidentified sculpin were caught in all three streams and in the Chuit River from May
through September (Table 4). Mean length for unidentified sculpin was 51 mm (15−104
mm). Mean weight for unidentified sculpin was 3.5 g (0.1−9.5 g; Table 9).
Slimy sculpin
Slimy sculpin were captured at all three study tributaries and the Chuit River throughout
the season (Table 4). Slimy sculpin averaged 63 mm in length (26−114 mm; Figure 29).
Mean weight for slimy sculpin was 3.2 g (0.5−10.0 g; Table 9).
Sockeye salmon (adult)
Two adult sockeye salmon were caught within the study area. One sockeye salmon was
captured in the Chuit River in late July. Another sockeye salmon was caught in Stream
2004 in early September. Lengths of the adult sockeye salmon were 495 and 545 mm
(mid-eye to fork; Table 9). No weights were taken on the adult sockeye salmon.
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Sockeye salmon (juvenile)
Juvenile sockeye salmon were only caught in Stream 2004 and the Chuit River (Table 4).
Sixteen juvenile sockeye salmon were caught in the Chuit River mid May through early
July. With the majority of juvenile sockeye salmon were captured in May (Figure 28).
One sockeye salmon was captured at the weir in Stream 2004 in September. Juvenile
sockeye salmon mean length was 39 mm (33−54 mm; Table 9; Figure 28). The only
weights taken on sockeye salmon juveniles were on small fish that weighed 0.5 g.
Threespine stickleback
Threespine sticklebacks were caught in Stream 2002 and the Chuit River (Table 4). The
sticklebacks were caught from May through September. Threespine stickleback mean
length was 53 mm (17−87 mm; Table 9; Figure 34). Mean weight of threespine
stickleback was 3.6 g (0.5−7.5 g).
4.2.4 Differences in fish species composition among sites
Species diversity was greatest in the Chuit River, but all species caught were also seen in
the tributaries (Tables 4 and 5). Juvenile coho salmon dominated the catches at all main
sampling sites. In Stream 200401 the catch was dominated by rainbow trout.
Differences in fish species composition occurred among the study tributaries. Ninespine
stickleback, threespine stickleback, Pacific Lamprey, and juvenile pink salmon were only
caught in Stream 2002. Both adult and juvenile sockeye and juvenile chum salmon were
captured in Stream 2004, and not observed in the other two streams. More adult lamprey
and lamprey ammocoetes were caught in streams 2002 and 2003, than in Stream 2004. A
larger number of Dolly Varden were seen in Stream 2003 and Stream 2004, than in
Stream 2002. The majority of rainbow trout were caught in Stream 2004 (even when
excluding Stream 200401). The run timing of rainbow trout ≥100 mm occurred early in
the season in Stream 2003 and at the end of the season in streams 2002 and 2004.
4.3 Fish Movement and Abundance in Tributaries – Fish Moving Upstream
4.3.1 Abundance and species composition
The video imaging system was operated from June 8 through September 19 in Stream
2002, from June 29 through September 30 in Stream 2003, and from June 29 through
September 30 in Stream 2004.
In all three streams, fish were identified to species for adult salmon (Chinook, chum
coho, pink, and sockeye), Dolly Varden, and rainbow trout. All lamprey species were
lumped into one group, as were all sculpin species. Juvenile salmon were broken into
size groups that approximated the age classes for coho salmon seen in the streams (<45
mm, 46−100 mm, and >100 mm); the number of fish assigned as coho or Chinook
salmon were based on the concurrent catch fraction from the weir. Dolly Varden,
rainbow trout, and lamprey were separated into two size groups to roughly approximate
older, mature fish and younger, immature fish.
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In Stream 2002, fish counts were primarily adult coho salmon (48% of detections) or
salmon smolt (38%). Fish moving into Stream 2002 were adult coho, Chinook, sockeye,
chum, and pink salmon, rainbow trout, Dolly Varden, sculpin, and smaller salmon
(estimated size 45−100 mm, or equivalent to age-1 coho salmon). Fish groups with a net
movement out of the system (downstream) were salmon smolts and lamprey (Table 12).
In Stream 2003, fish detected in the video were primarily adult coho salmon (37%) and
juvenile salmon of a range of sizes (36%). Adult Chinook, coho, sockeye, and pink
salmon moved upstream. No adult chum salmon were seen. There was also a movement
upstream of Dolly Varden, the smallest two length classes of salmon (fish <45 mm and
46−100 mm), and smaller rainbow trout. Net movement out of the system (downstream)
was documented for larger rainbow trout, lamprey, sculpin, and salmon smolts.
In Stream 2004, fish detected in the video were primarily juvenile salmon of a range of
sizes (36%), adult coho salmon (20%), rainbow trout (19%), and Dolly Varden (12%).
Adult coho, Chinook and sockeye salmon were moving upstream; no chum or pink
salmon were seen. Larger Dolly Varden and rainbow trout (Photo 22), along with a few
sculpin also moved upstream. Fish groups with a net movement downstream, out of the
system, were all juvenile salmon, smaller Dolly Varden and rainbow trout, and lamprey
(Table 12).
4.3.2 CPUE and run timing of fish groups moving upstream
Adult coho salmon
Relatively small numbers of adult coho salmon returned in late July and early August to
streams 2002 and 2003, but not to Stream 2004. Adult coho salmon were not seen again
until September 3, when large numbers of fish entered all three streams (Figure 38).
Thereafter, run timing was similar on each stream. Twice (September 3 and 7), distinct
pulses of adult coho salmon entered all three streams on the same day; both dates were
associated with high-water events. On a third date (September 9), a distinct pulse of fish
entered both stream 2002 and 2003, but the water in Stream 2004 was too high to count
fish by any method. If adult coho movements into Stream 2004 tracked the other streams
on September 9 the way they did on September 3 and 7, this inability to count fish on
September 9 may have partially accounted for the fewer fish seen returning to Stream
2004 (Appendices E, F, and G).
Adult Chinook salmon
CPUE of adult Chinook salmon was higher in Stream 2002 than in streams 2003 and
2004. Small numbers of jack Chinook salmon were seen in Stream 2002 in mid June.
The main run of adult Chinook salmon came from mid July through mid August (Figure
39). Jacks preceded the larger fish in Stream 2002, but not on the other streams (Figure
40).
Adult sockeye salmon
Small numbers of adult sockeye salmon returned to streams 2002 and 2003 between late
July and early August (Photo 23; Appendices H and I). Stream 2004 had the greatest
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number of sockeye detections, with the first on August 30 and last on September 25
(Appendix J).
Adult pink salmon
Pink salmon first appeared at Stream 2002 on July 18, peaked on July 27, and were last
detected on August 7 (Appendix H). The few pink salmon recorded in Stream 2003 were
seen between July 26 and 29.
Adult chum salmon
The video recording system captured a single adult chum salmon moving upstream in
Stream 2002, on September 18 (Appendix H).
Rainbow trout
Rainbow trout moved both upstream and downstream during the entire period that video
cameras were operational; peak activity varied among streams (Figure 10).
4.3.3 Differences in upstream movement among streams
Stream 2002 had the greatest number of adult coho, Chinook, and pink salmon, and was
the only stream in which adult chum salmon were detected. It also had the greatest
number of the larger size class of rainbow trout and Dolly Varden move upstream (Table
12).
Stream 2003 had the second greatest number of adult sockeye salmon, behind Stream
2004, although this number was still small compared to most other salmon (24 adult fish).
There was a net movement of larger rainbow trout out of the system, unlike on the other
streams. Counts of adult coho salmon were lower than in Stream 2002, but higher than in
Stream 2004.
Stream 2004 differed from the other streams in that it had fewer returns of adult coho and
Chinook salmon and no returns of adult pink or chum salmon. There was also a strong
net movement of salmon “fingerlings” (likely age-1 coho salmon) and rainbow trout fry
out of the system (opposite of that seen in streams 2002 and 2003). As with the counts
from the holding boxes (Section 4.2.3), there were far fewer lamprey (both size classes)
seen on the video in Stream 2004 than in streams 2002 and 2003.
4.3.4 Image analysis on the video system
In the early season, tests showed that adult fish passage could be accurately assessed with
motion detection events. As the season progressed and conditions changed, false motion
detection events from debris, fluctuating light, bubbles in the water column, etc., became
more prevalent, resulting in an unacceptable number of false detections despite diligent
efforts to adjust sensitivity. For this reason, motion detection was not used to estimate
adult salmon passage as originally intended. Instead, adult fish passage was estimated by
the same method as with other species, using time-lapse video and 15 minute subsamples
per hour. At times when fish were especially numerous, the 15-minute subsamples were
validated with full-hour counts.
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Total fish counted using the expansion method (from 15-minute subsamples) were
compared to counts from the full hour at 50 different times (on September 3, 4, 7 and 9 in
Stream 2002). These dates were identified from subsamples as high coho salmon
movement periods in Stream 2002. Three of these periods were during a time of net
upstream migration and one was during net downstream movement.
Combining all four time periods, the upstream coho salmon movement found using full
counts was 1,935 and that estimated through subsampling techniques was 1,916.
Subsampling thus accounted for 99% of the full census counts in Stream 2002. This
method was also applied to streams 2003 and 2004.
4.3.5 Visual counts during flood events
Unexpanded, full-hour counts of fish passing though breaches in the weir at Stream 2002
between September 14 and 18, resulted in 21 adult coho salmon moving upstream (Table
6 and Appendix E). No other fish were observed.
At Stream 2003, using a combination of full-hour counts and subsample visual counts,
six coho salmon were estimated moving downstream and 531 upstream on ten dates in
September. The majority of these upstream movements occurred on September 3 and 9
(246 and 234, respectively; Appendix F). An additional 27 adult salmon, which could
not be identified due to flood conditions, also were counted visually moving upstream
(Table 7).
Both full-hour and subsample counts were also used at Stream 2004 to estimate a total of
one coho salmon moving downstream and 26 upstream. Most of these movements
occurred on September 14 (Appendix G). An additional ten adult salmon of unknown
species were also counted visually moving upstream at this site (Table 8).
4.4 Abundance of Coho and Chinook Salmon Smolts in the Chuit River Watershed
In total, 14,695 coho salmon ≥80 mm in length were marked at the weirs. Marked fish
were released in four different temporal strata, starting on May 30 and ending September
12 (Table 13). In total, 1,412 coho salmon ≥80 mm in length were examined for marks at
the RSTs with 352 recaptures identified. We estimated travel time from the three study
streams combined to the RSTs in the Chuit River was two days for most marked fish,
with 99% of the recaptured coho smolts passing within six days or less after being
marked upstream at the weirs (Figure 41). There was no difference in size between coho
salmon captured in the RSTs with and without marks (KS test; P-value > 0.05; Figure
42). An attempt was made to also estimate Chinook salmon smolt abundance, but not
enough fish were caught in the tributary streams to provide a credible estimate.
Coho salmon smolt abundances were calculated separately for each of three size classes,
based on the appearance of smolting, the run timing of the fish, and apparent size
selectivity of the gear. The main group of smolts were those ranging in size from the
largest that were both marked and recaptured (161 mm), down to the smallest that
appeared to be smolts throughout the entire run, based on combinations of age, size, and
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smolt appearance. This lower size limit was 90 mm (Figure 16). Within this size range
(90 to 161 mm), the probability of capture varied with fish length. The cut point of this
discrepancy occurred at 117 mm, and fish were thus stratified into two size groups, one
from 90−117 mm, and the other from 118−161 mm (Figure 42). Both size groups
required the Darroch model to meet Assumption 2 (all p-values from the diagnostic tests
were less than 0.01). After final pooling in SPAS, the 90−117 length group was divided
into four temporal tagging strata and three recovery strata while the 118−161 length
group was divided into three tagging and two recovery strata (Table 13).
Abundance estimates were also calculated for a third group of fish (80-89 mm), which
were younger (age-1) coho salmon that had the appearance of smolts early in the season,
but did not later in the season. The abundance of this smolt group was calculated based
on fish migrating within the first (and largest) temporal stratum, which was from May 30
to July 6. Because these fish were migrating within one previously identified temporal
stratum, the PPE method was used to calculate their abundance.
The final population estimate for all three groups of smolts combined was 37,424, with a
95% confidence interval ranging from 33,276−41,572 (Table 14). For all three length
categories combined (for the June 1st to July 19th time period), 20.7% of the coho salmon
smolts in the Chuit River would be attributed to Stream 2003. Abundance estimates (and
95% confidence intervals) for the individual size classes for the entire Chuit River
watershed were as follows:
Group 1 (80−89 mm): 5,500 (3,041−7,959).
Group 2 (90−117 mm): 22,011 (19,698−24,324).
Group 3 (118−161 mm): 9,913 (7,503−12,323).
4.5 Environmental Conditions
4.5.1 Ice and snow out
Ice began to melt from streams 2002 and 2003 in late April and from Stream 2004 in
early May. Streams 2002 and 2003 were mostly ice free by early May; snow had melted
from the lower reaches of the streams, but was still extensive in the upper reaches.
Stream 2004 was mostly ice free by mid May; snow had melted from the lower portions
of the stream, but was still extensive in the upper reaches. The snowpack was completely
melted at all three sampling sites by early June.
The Chuit River was relatively ice free in early May, although some ice was still flowing
downstream from the tributaries. The snowpack near the sampling sites was completely
melted by mid May.
4.5.2 Water temperature
Water temperatures recorded with the remote loggers show similar trends among the
tributary streams. Water temperatures ranged from 0 to 1 ˚C (32 to 33.8 ˚F) in early May.
Through early June, daily water temperatures generally ranged from 7.7 to 12.1 ˚C (45.8
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to 53.8 ˚F). Stream temperatures gradually increased in June, then peaked in July.
Streams 2003 and 2004 peaked on July 5, with 14.2 ˚C (57.6 ˚F) at Stream 2003 and 14.3
˚C (57.8 ˚F) at Stream 2004. Stream 2002 peaked at 14.4 ˚C (57.9 ˚F) on July 31. Water
temperatures remained fairly constant in July and August, ranging from 10.2 to 14.4 ˚C
(50.3 to 57.9 ˚F). Water temperatures decreased thereafter, dropping to a range of 2.9 to
3.8 ˚C (37.2 to 38.8 ˚F) by the end of the September (Figures 43 and 44).
In the Chuit River, water temperatures followed a similar pattern as in the tributaries, but
lagged the tributaries by about two weeks. In early May, water temperatures varied
between 0.2 and 1.1 ˚C (32.4 to 34 ˚F). Water temperatures increased more gradually in
June than in the study tributaries, then leveled out in early July and peaked at 15.7 ˚C
(60.3 ˚F) on July 31. Temperatures varied from 11.7 to 14.3 ˚C (53.1 to 57.7 ˚F) through
August, then decreased through September (Figures 43 and 44).
The temperature loggers failed to record data on several occasions during the season.
The logger on Stream 2002 was not set properly and did not record temperatures from
June 20 to June 27. The logger in Stream 2004 did not record temperatures from May 22
to June 16. No temperature data are available for Stream 2003 on July 25 and July 26.
The logger did not record temperatures from the Chuit River from July 25 to July 27.
Average bulb temperatures collected at each sampling event were used as surrogates from
the time period when temperature logger data was missing.
4.5.3 Discharge
In the spring, as the snowpack melted there was an associated rise in discharge from the
tributaries. According to the preliminary data furnished by RTI, water levels rose in the
tributaries until mid May, peaking at 7.3 m3/s (258 ft3/s) in Stream 2002 and 4.8 m3/s
(169 ft3/s) in Stream 2003 (May 12). Discharge data were not available in May for
Stream 2004, but it is likely Stream 2004 also peaked in May. Discharge in Stream 2004
was highest on June 1 at 4.6 m3/s (164 ft3/s), the earliest date available, and declined
thereafter (Figures 4 and 45). Discharge data were not available for the Chuit River.
Water was clear in streams 2002 and 2003 by June 1 and in Stream 2004 by June 15.
Water levels remained low and relatively constant for the duration of the July and August
with the exception of rain events. Water discharge increased again in September due to
precipitation (Figure 46).
After rain events the streams discharge and turbidity would increase, then subside within
hours or days, depending on the rain event. During high water events, Stream 2003
appeared to peak the fastest, but would then subside quickly. Stream 2002 didn’t peak as
high but the water levels remained higher longer. The effects in Stream 2004 were more
moderate in comparison to Streams 2002 and 2003; water levels didn’t peak as high as in
Stream 2003, and did not remain high for as long as in Stream 2002. Discharge on the
Chuit River was influenced by the tributaries, rising and falling after associated events in
the tributaries. Water turbidity increased with discharge.
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4.5.4 Precipitation
Precipitation occurred throughout the course of the season with the heaviest rainfall
occurring in late July and throughout September (Figure 47). According to data collected
by McVehil-Monnett, rainfall from May through early July did not exceed 1 cm (0.4 in)
per day. From mid July through the end of the month rainfall increased. Precipitation
peaked on July 24 at 1.7 cm (0.7 in). During the month of August rainfall decreased and
did not exceed 0.5 cm (0.2 in) per day. Rainfall again increased during September.
Precipitation peaked on September 14 at 2.3 cm (0.9 in) (Data supplied by T. Holmes,
McVehil-Monnett Associates, Inc., November 18, 2008).
Within our study tributaries and on the Chuit River heavy and persistent rainfall led to an
increase in discharge, or “high water events”. It was during these high water events that
our sampling equipment was most likely to have reduced effectiveness, in some cases
halted altogether.
5.0 Discussion
5.1 Overview of Fish Species Composition in Tributary Streams
5.1.1 Fish species and abundance in each stream
More fish species and greater numbers of salmon were captured in Stream 2002 than
Stream 2003, which in turn exceeded Stream 2004 in species number and salmon catches.
Given the relatively complete fishing coverage by all three weirs through the study
period, our catches reasonably capture relative differences in fish movements among
streams. Fish species composition differed among the three tributaries in a way that was
consistent with tributary position in the watershed. Moving from downstream to
upstream, the three streams decline in watershed area and stream size, and the total
amount of combined high flow/low gradient habitat area decreases. All five species of
adult salmon were found in the Chuit River watershed, and each showed a decreased
tributary abundance from downstream to upstream. The decreased abundance of chum
and pink salmon from downstream to upstream is consistent with results from the Chuit
River in 1983 (ERT 1984). Such trends may reflect a preference for the combination of
low gradient / high discharge habitat typical of lower watershed reaches, and has been
documented elsewhere for these species. The decline in coho and Chinook salmon when
moving upstream was also reasonable in the absence of any unusually different habitat
features. The pattern among the streams may be an indicator that watershed position and
its effects on stream size, gradient, and discharge may be the strongest influence on
salmon habitat in the Chuit River watershed. Lamprey species also showed a decline
from downstream to upstream, consistent with the idea that this anadromous fish is better
suited for migrations low in the system than higher up.
Relative catches of Dolly Varden and rainbow trout were also consistent with their
known life history and ability to inhabit relatively small streams at some or all life stages.
Unlike salmon and lamprey, catches of these two species remained relatively constant
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from downstream to upstream. Stream 2004 had greater catches of Dolly Varden and
rainbow trout than the other two streams. The Dolly Varden finding was similar to 1982,
when Stream 2004 was concluded to have the most productive rearing habitat for Dolly
Varden (ERT 1984). Catches of newly hatched rainbow trout were much higher in
Stream 200401 (tributary to Stream 2004) than in the other two tributaries, although this
difference is confounded by the use of a gear type with smaller mesh (fyke net) than was
used on other systems. Even so, the weirs should have been able to catch some of the
newly emerged rainbow trout fry caught in the Stream 200401 fyke net, suggesting that at
least some part of the increased catch on Stream 200401 was due to a true increase in
production of rainbow trout fry in the Stream 2004 watershed.
Overall, this study provides some evidence that Stream 2003 is more similar to Stream
2002 than 2004 in terms of seasonal fish movements, that the relative abundance of these
moving fish is somewhere in between the other two streams, and that the species
composition of fish moving in each tributary may be a reflection of physical
characteristics related to relative watershed position. Relative contributions of Chinook,
coho, pink, and chum salmon among the three tributaries in 2008 were consistent with
distributions reported by ERT (1984) in 1983.
Adult coho salmon were more abundant than documented in the 1980s, whereas
abundance of adult Chinook salmon was lower. For both species, the differences
between our study in 2008 and studies from the 1980s are within the range of interannual
variability found for other populations within Cook Inlet (e.g., Lafferty et al. 2007 for
coho salmon; Shields 2007 for Chinook salmon). In the early 1980s, ERT (1984)
estimated a coho salmon escapement of up to 1,800 fish in the entire Chuit River
watershed; in 2008, this range was exceeded by our estimate into Stream 2002 alone, and
our minimum estimate from the three study tributaries (4,017 fish) was over twice the
watershed-wide estimate in 1983. Adult Chinook salmon escapements in 1983 were
estimated at 6,705 in the entire Chuit River, 531 in Stream 2002, 303 in Stream 2003, and
68 in Stream 2004 (ERT); results from this study in 2008 were lower for each tributary
(Table 12). The overall returns of coho salmon to upper Cook Inlet were thought to be
above average in 2008 (ADF&G 2008). Chinook salmon returns to the region were
below average, with the largest run in the region (the Deshka River) falling below the
escapement goal (ADF&G 2008).
Adult sockeye salmon were present in low numbers in all three study tributaries in 2008
(Photo 23), but had not been documented in prior field surveys from 1982 through 1984
and again in 2006 and 2007 (ERT 1984; Oasis 2007). The only prior description of adult
sockeye was from low numbers captured as bycatch from a Chinook salmon fishery in
the lower mainstem Chuit River (EPA 1990). Adult sockeye salmon runs to the rest of
upper Cook Inlet were unusually low in 2008 (ADF&G 2008), decreasing the chance that
these observations are anomalies or stray fish from unusually abundant runs to nearby
rivers.
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5.1.2 Basic run timing of key fish species
Coho salmon smolts
Coho salmon smolts migrated from approximately early June through the first week of
July. The smolt run began a few days earlier in Stream 2002 than 2003, which in turn
began a few days earlier than in Stream 2004. Such differences, although minor, should
be considered in any future monitoring plans.
Emigration timing of juvenile coho salmon from the tributaries to the Chuit River
confirmed some basic migration patterns suggested by studies from the early 1980s (ERT
1984) and in 2006 (Oasis 2008). These prior studies did not monitor passage from the
tributaries, but instead inferred migrations based on temporal differences in electrofishing
and minnow trap catches. These studies suggested that up to three age classes of juvenile
coho salmon were present in tributary streams (ERT 1984), similar to our study in 2008.
ERT (1984) suggested that age-0 (newly-hatched) juvenile coho salmon become mobile
at some point in the early summer, and that age-2 coho salmon migrate to sea from mid
June through mid July. Our data from 2008 support these patterns, with a slightly earlier
emigration time of age-2 smolts. The ERT research also suggested that age-1 coho
salmon emigrated from the tributaries in late summer, and concluded that the fish were
smolting and going to sea. We saw a similar emigration trend in 2008, but cannot
conclude that the fish were migrating to sea; instead, these fish could have overwintered
in the Chuit River in preparation for migration to sea the next spring (as age-2 fish). This
run of age-1 fish that emigrated from July through September appeared distinct from an
earlier, less abundant run that migrated at the same time as age-2 fish.
Adult coho salmon
The bimodal run timing of adult coho salmon into the Chuit watershed was consistent
with observations from 1982 and 1983 (ERT 1984), when coho salmon were detected in
late July and again in August. The run in 2008 was more spread through time (late July
and again in early September), possibly due to differences in precipitation patterns.
Notably, the early run was not observed in Stream 2004 in either 1983 or in 2008.
Juvenile Chinook salmon
Overall, the abundance of juvenile Chinook salmon declined from downstream to
upstream, with the largest proportion of fish in the mainstem river. A similar trend was
observed in the 1980’s; the largest catches occurred in the Chuit River and in lower to
middle sections of streams 2002 and 2003 (ERT 1984). Relative abundance and
distribution were higher in the 1980s than in 2008 (ERT 1984).
Adult Chinook salmon
The run timing of adult Chinook salmon into the Chuit River watershed (mid July
through mid August) in 2008 was consistent with observations from the 1980s (EPA
1990), and in 2007 (Oasis 2008). In 2007, Chinook were documented on August 8 and
27 in aerial surveys, but not on July 31 or September 14 (Oasis 2008). In 2008, Chinook
were documented in the tributaries from July 17 through August 17; the earlier arrival in
2008 than 2007 may be partially due to the greater resolution provided by the weirs and
video systems, allowing fish to be detected when density was low.
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Rainbow trout
The separate fyke net on Stream 200401 documented an obvious pulse of newly-hatched
rainbow trout not previously described in the system. The gear at this site was perhaps
the best suited for documenting these fish; the mesh was small enough to hold these fish,
and the stream was small enough to be completely blocked off by the netting. Although
some sampling in prior years had shown the recruitment of these fish, the gear (usually
minnow traps) would not have been optimal for catching this group of fish. We cannot
know if other, similarly sized tributaries would have contained such rainbow fry had we
been able to sample them with similar gear, but it is worth noting that in 2006 and 2007,
Oasis (2009) consistently found more rainbow trout in Stream 2004 than in streams 2002
and 2003. Based in these prior findings and on our results in 2008, it appears that Stream
2004 may be especially suitable for rainbow trout, and contain at least two year classes of
juveniles; one that is present throughout the open-water period, and another that hatches
in mid summer and moves actively for a short period of time. Movements through the
weir by these fish may not have necessarily been indicative of fish migrating to the
mainstem; rather, it could have simply been fish dispersing into Stream 2004 shortly after
emigrating from their nearby natal stream.
Dolly Varden
In general, run timing of Dolly Varden was highest in May (Stream 2003), late August
(Stream 2004), and early September (Stream 2002) and larger catches were often
associated with increased discharge. Observations in prior years have shown variability
in relative abundance, but with peaks at all the same times noted in 2008. In the 1980s
(ERT 1984) and again in 2007 (Oasis 2008), catches were higher in August and
September than earlier in the season. In 2006, by contrast, the highest catches of Dolly
Varden came early in the season (Oasis 2008). Overall, our results were consistent with
prior years, but it appears that migration patterns of Dolly Varden may be especially
likely to change from year from to year.
Lamprey species
Although the presence of lamprey species (both Arctic and Pacific) was previously
documented in the Chuit River watershed, information on run timing was not provided in
prior reports (ERT 1984; Oasis 2008). In our study in 2008, the majority of adult Arctic
lamprey moved downstream from early June through mid July. Although we could not
identify immature lamprey (ammocoetes) to species, they had a similar run timing to
Arctic lamprey, which were in turn the most dominant lamprey group seen. It seems
likely that the ammocoetes were Arctic lamprey. The few Pacific lamprey detected
migrated during the first half of July. We believe that the first few Pacific lamprey seen
were misidentified as Arctic lamprey by crews used to seeing only Arctic lamprey up to
that point – this misidentification would account for the few unusually large Arctic
lamprey shown in late June, ones that were the size of Pacific lamprey (Figure 24).
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5.2 Coho Salmon Ecology within Streams 2002, 2003, and 2004
5.2.1 Life history of juvenile coho salmon
Migrations of juvenile coho salmon in 2008 suggest a life history pattern in which coho
salmon hatch in early to mid summer, then remain largely within their natal tributaries;
we saw few age-0 coho salmon moving past the video camera, relative to the numbers
that are likely to be in the stream based on adult returns. In 1982 and 1983, the
abundance of age-0 coho salmon throughout the three study watersheds remained high
from mid to late summer, supporting our conclusion from the 2008 data that most age-0
coho salmon remain within their natal tributaries through at least September.
Many age-0 fry rear in tributaries through the winter, becoming age-1 the following
spring. Some of these age-1 fish then smolt in early summer and migrate from the
tributaries to the ocean. In 2008, these age-1 smolts were not as numerous as the older,
age-2 smolts. Some of the remaining age-1 fish migrate from the tributaries later in the
summer or fall; in 2008, we captured these fish migrating to the Chuit River from all
three tributaries, through the summer and fall. We did not see a reciprocal movement
upstream during this time, indicating that these downstream movements represented an
overall redistribution within the watershed, and that the fish likely overwintered in the
mainstem or in other tributaries not being monitored, or died. Finally, a third group of
age-1 fish did not emigrate from the tributaries, but instead remained overwinter. These
fish would then enter the next spring as age-2 smolts; in 2008, such fish represented a
large majority of the smolts emigrating from each of the three study tributaries.
The fate of fish that emigrate from the tributaries as pre-smolts (e.g., age-0 or age-1 fish
in the summer and fall) is important because it contributes uncertainty to the final
estimate of smolt production from each tributary in 2008. If these pre-smolts have high
survival elsewhere and then smolt in 2009, then the natal stream is acting as a production
source that is ultimately responsible for the production of more smolts than we estimated
using only counts of fish migrating in June and early July in 2008 – for example, the
stream produced one group of smolts by providing rearing habitat to age-2, and another
group by providing rearing habitat for age-1 fish until they are large enough to occupy
habitat elsewhere. Conversely, if these fish are essentially extraneous juveniles getting
outcompeted for suitable habitat (in the natal stream), they would have reduced survival
and could contribute relatively little to the smolt run in 2009. The reasons for this
downstream movement (i.e., to access superior habitat or from being pushed into inferior
habitat) is not known, but would indicate whether these fish are relatively likely or
unlikely to make important contributions to the number of smolts produced by the natal
tributary.
Both life history strategies by age-1 fish (redistributing to the mainstem as age-1 fish, or
overwintering in the tributaries until age-2) have precedent within the literature. Juvenile
coho salmon are known to redistribute themselves downstream over the course of their
freshwater lives, apparently in search of better food or habitat, or to smolt from a distance
closer to the ocean the next spring. On the Kenai River, age-1 coho salmon are known to
redistribute among tributaries, moving from those where they hatched to those with
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relatively better rearing habitat. Age-1 coho in this system also appear to overwinter in
the mainstem river, then move back into tributaries in the spring (R. Massengill,
ADF&G, personal communication).
5.2.2 Smolt status
Prior studies in upper Cook Inlet show that adult coho salmon returns are primarily fish
that migrated at age-2 (e.g., two winters spent in freshwater), with the additions of some
fish that migrated at age-1. The number of coho salmon smolts from a system is often
difficult to quantify exactly because of some uncertainty as to the exact smolting status of
every fish examined; more specifically, what portion of the age-1 smolts migrate to sea
that year and which ones remain overwinter and migrate the following year at age-2?
Although smoltification can often be determined visually at the point of ocean entry, it is
more difficult to determine further upriver because not as many of the physiological
changes that allow easy visual identification have occurred.
In the Chuit River in 2008, we reduced the potential for bias in smolt abundance by
separating juvenile coho salmon into three potential smolt groups: (1) age-2 coho salmon
detected in any obvious run in the spring or early summer, when coho salmon smolts are
known to migrate; (2) age-1 fish that migrated concurrently with the age-2 smolts; and,
(3) any age-1 or -2 fish that migrated after the main smolt run appeared to have ended.
Group 1 was immediately obvious during field sampling; these fish were large, had the
appearance of smolts, migrated during the time we expected smolts to migrate, proved to
be mostly age-2, and were consequently considered to be smolts. From group (2), we
included those fish that had the appearance of smolts, which were generally fish down to
about 80 mm in size. From group (3), we did not include these fish in the tallies of
smolts from the tributaries – there were few to no age-2 fish in this group, eliminating
these as a concern. Age-1 fish were abundant in the tributaries, and of a size seen earlier
in the season, but did not have the obvious smolting characteristics seen earlier in the
year.
Our final estimate of smolts from the tributaries thus consisted of mostly age-2 fish (all
sizes), a small number of age-1 fish (down to 80 mm in length), and none of the latesummer migrants that ERT (1984) considered smolts. In reality, some of these fish may
have indeed also smolted that year, but it would be impossible to quantify this proportion
with the data we have collected. Unpublished data from LGL Alaska from the Nome
River in Alaska (B. Williams, unpublished data) showed that late-summer migrants (e.g.,
in July and August) were significantly less likely to migrate to sea that year than smolts
migrating earlier (e.g., in June); if the same trend applies to the Chuit River, we were
correct to not count these fish as smolts in 2008.
Nevertheless, at least some age-1 coho salmon that migrate downstream from the study
tributaries from July through September will become smolts the next year, and should be
ultimately counted as smolts produced by their natal streams. The number of smolts that
result from these fish is the product of the initial abundance of age-1 migrants and their
rate of survival through the winter of 2008/2009 (Nickelson 1998). As noted above, this
survival rate could range from relatively low (if these are fish that have lost a competition
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for space and have thus been pushed out of excellent habitat in Stream 2003) to relatively
high (if they are en route to better overwinter habitat that will enhance their survival
relative to fish that remained in Stream 2003). In the Chuit River, the relative habitat
quality, use by juvenile coho salmon, and survival rate of these salmon has not been
evaluated among the different tributaries, or between the tributaries and the mainstem
river. Oasis et al. (2008), however, has classified habitat within much of streams 2002,
2003, and 2004, and described length structures of coho salmon captured in minnow traps
in different portions of the watershed. This information would need to be augmented
with studies within the mainstem river and with studies of habitat use and survival by
age-1 coho salmon to explain the reasons for emigration from the tributaries to the
mainstem river by pre-smolt coho salmon.
5.2.3 Coho salmon size, body condition, and age
Early in the summer, juvenile coho salmon in the tributaries were larger and had higher
body condition than their same-age counterparts in the Chuit River. For age-2 fish, the
length differences have been due to selectivity for smaller fish by the RSTs. Such
selectivity did not apply to age-1 fish, however, because there was less observed catch
bias by gear type for their size class. Furthermore, sizes of age-2 fish converged
(between the tributaries and mainstem river) in late June (Figure 48), with coho from the
tributaries averaging the same length as the RSTs were capable of catching. Overall,
early-season difference in sizes between tributary and mainstem coho salmon appears
legitimate, even if possibly accentuated by size selectivity in the Chuit River.
The observation that larger smolts emigrated first from the tributaries may also explain
the patterns in body condition seen in all three streams. At the start of the smolt run,
relative weights (the body condition index) were high, as larger, more robust fish
migrated to sea first. Smaller, less robust fish may have had to wait longer in the stream
before attaining the size needed to survive at sea, and thus were captured slightly later in
the season (e.g., mid to late June). Body condition of these smolt-sized fish began to rise
just before the end of the smolt migration (Figure 19), in response to increased food
resources as the summer progressed. Body condition was much lower later after the
smolt run ended (e.g., mid-July through September) because the larger, more robust fish
had emigrated; thereafter, body conditions were stable or increased as these smaller fish
remained within the system and continued to grow through the summer and fall.
Body growth of fish can be difficult to measure from group sampling if one size class of
fish emigrates and is replaced by another. In Cook Inlet, Moulton (1997) found that
juvenile salmon growth was likely masked by such a replacement of one size group by
another. The size-based migrations within the Chuit River in 2008 may have similarly
affected lengths over time, hindering computations of true growth over time for coho
salmon. Within the tributaries in 2008, sizes of both age-1 and age-2 coho salmon
dropped through mid July (Figure 48), probably due to the early movement of larger fish
(described above) and subsequent replacement by smaller ones (Figures 49 through 51).
The concurrent increase in size of fish in the Chuit River was likely due to the influx of
these larger fish from the tributaries, and therefore not representative of the true rate of
body growth. After the smolt run ended in mid July, age-1 coho salmon were
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temporarily the same size in the mainstem river and the tributaries. Thereafter, fish
lengths in the tributaries remained relatively static, likely because any growth was
masked by the movement of larger fish from the system and their subsequent replacement
by remaining smaller fish. Concurrently, fish in the Chuit River increased in length,
suggesting that fish were not leaving the system, and were instead both growing and
receiving population inputs from the tributaries (Figures 49 through 51).
5.2.4 Chuit River coho salmon relative to other populations in Cook Inlet
Little is known about juvenile coho salmon elsewhere in the region because most
assessment studies focus on adult salmon. One exception is on the Kenai River, where
coho salmon smolts were monitored from 1992 through 2007 (Massengill 2008). Age
structure and body size of juvenile coho salmon appears to similar to that noted in the
Chuit River in 2008; R. Massengill (ADF&G, personal communication) estimates that
age-2 smolts account for approximately 80% of the smolt run from the Kenai River, and
that many smolts exceed 120 mm in body length. Smolt migration from the Moose
River, a side tributary ~ 36 km from the ocean, usually occurs between mid May and mid
June, approximately two weeks before the migrations seen in 2008 on the Chuit River
(Massengill 2008). Juvenile coho salmon have also been studied recently in Cottonwood
Creek, in Upper Cook Inlet; data from this study are not yet available.
5.3 Abundance of Coho Salmon Smolts in Tributary Streams Versus the Chuit
River Watershed
5.3.1 Estimated abundance of coho salmon smolts in the Chuit River watershed (markrecapture model)
We believe the size and time stratified model provided the best mark-recapture estimate.
Below we discuss the validity of this estimate organized by the assumptions upon which
it is based. Overall, we deem any violations of Assumptions 1, 4, and 5 to be highly
unlikely (see section 4.4). The possibility of handling induced mortality during the
marking process was negligible given the low mortality rates of coho salmon smolts
handled on other studies with much more invasive markings (e.g., coded wire tagging;
Williams et al. 2006) and the fact that we recaptured a high proportion of our marks, and
often within two days of release. We also do not think that fin marks, although meant to
be temporary, could regenerate during this time frame. Nonreporting was unlikely to
have introduced appreciable bias because each fish at the recapture site was carefully
scrutinized for marks.
Uncertainty exists regarding the abundance of outmigrating smolt for the smallest size
grouping. We first separated coho salmon into <90 mm and ≥90 mm groups because of
the questionable status of the smaller size grouping as smolts in 2008. The larger fish
were silvery in appearance and were not observed milling at any of the sampling sites,
but moved through the system rather quickly. It was less clear if all coho salmon in the
80-89 mm size class were smolting, and the possibility exists that a number of them
simply moved from the tributary streams to the Chuit River, but did not outmigrate. This
group exhibited a spike in p1 during the third tagging stratum, which corresponded to a
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high discharge event during that time period. This further fueled suspicion that fish of
this size group were not outmigrating as smolts later in the season, but were being flushed
out of these tributaries into the mainstem. This occurrence would not bias the abundance
estimate for 80-89 mm fish, but rather our estimate of smolts outmigrating in 2008. If a
portion of these fish failed to outmigrate, then they will be correctly included in the
estimate for 2009, but also incorrectly included in the estimate for 2008.
Assumption 2 was addressed with size and temporal stratification. The remaining size
stratifications into 90-117 mm and 118-161 mm groups was necessary because larger fish
exhibited lower catchabilities at the RSTs (a common phenomenon for RSTs), thereby
causing inconsistency in p2 across all individuals. Bias from size selective sampling was
removed only to the extent provided by the resolution of the size stratification (more
strata might remove more bias, but increase variance). However, the estimate did not
actually change substantially from before size stratification was implemented.
Nevertheless, the KS test was able to detect differences in p2 from random chance and the
variance did not inflate appreciably as a result of using two size strata.
Because we tagged many of the smolts leaving the tributaries with weirs, p1 in this
experiment can be thought of as the probability of being from one of these three
tributaries. For streams 2003 and 2004, we captured and marked a very large portion of
the outmigrants (72% of the outmigrants in 2002 went through the video chute and were
not marked). Over time, p1 declined for the two larger groups (Table 13) leading to a
bias in the PPE model; the Darroch model removed this bias as much as the temporal
stratification would allow.
Assumption 3 required that p2 be equal for marked and unmarked fish. If the marked fish
from the tributaries experienced a different probability of capture in the RSTs than
unmarked fish (independent of size-related differences we have accounted for), then a
bias of unknown magnitude and direction could exist in our system-wide coho abundance
estimate. The probability of capture at the RSTs (p2) was more stable over time
compared to p1, although not enough to allow the PPE model to be used. Temporal
stratification was used in the Darroch model to incorporate changes in p2 and p1 and lack
of mixing through time. If the stratification was successful, these probabilities were
constant across individuals and/or mixing occurred within each stratum and any
differences among strata were accounted for with the Darroch algorithm. However, if
fish from tributaries without weirs experienced catchabilities at the RSTs that differed
from fish originating from tributaries with weirs, then a bias of unknown magnitude and
direction could exist.
The Darroch algorithm only deals with changes in p2 through time and assumes these
changes were constant across fish regardless of origin. Because most fish from the
tributaries with weirs were marked, the preceding scenario was essentially the same as
saying marked fish experienced a different p2 than unmarked fish (Assumption 3). Such
a scenario could occur if outmigration timing differed between smolts from tributaries
with and without weirs and capture efficiency at the RSTs changed due to fluctuating
stream discharge, or if fish from different tributaries were of such different sizes as to be
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differentially susceptible to the gear. This latter alternative seems unlikely given the lack
of size difference between marked (all of which were from the study tributaries) and
unmarked fish (nearly all of which were from the non-study tributaries). Significant
changes in RST capture efficiency should have manifested in more disparate p2 estimates
across recovery strata, and as this was not the case we consider the differences in p2 for
smolt from tributaries without weirs to be small and inconsequential.
5.3.2 Proportion of coho salmon smolts produced in Stream 2003 versus entire Chuit
River watershed
Our estimates of the contribution of smolts from Stream 2003 to the entire Chuit River
could be biased by comparing fish from somewhat different time periods. Smolt
abundance from each tributary stream was restricted to fish that emigrated from the
tributaries before July 19, based on post hoc assessment of data. The abundance within
the overall Chuit River, however, included fish after July 19 (although only for fish over
90 mm) because it was uncertain when smolts stopped emigrating from the tributaries
that were not monitored, and how long it would take for these smolts to move through the
watershed. In reality, few large fish were caught in the Chuit River after July 19,
minimizing any potential error from this difference in time periods.
Counts from each tributary clearly identified the number of age-2 fish and larger age-1
fish that were smolting early in the season. All fish within these groups could reasonably
be expected to migrate past the RSTs (an assumption that was supported by catch data),
and the watershed-based estimate thus compared proportions of fish from an equivalent
group (e.g., age-2 fish and large age-1). The same comparison cannot be made for age-1
pre-smolts that moved from the tributaries to the Chuit River later in the summer. If
these fish were destined to rear and overwinter in the watershed, they may not have
migrated downstream past the RSTs, and would thus not be vulnerable to recapture.
Therefore, the best estimate for the contributions of smolts from the tributaries to the
Chuit River watershed is one that restricts the analysis to the age-2 and larger age-1 fish
whose population size can be estimated in both the mainstem and in the tributaries.
The estimate of smolt abundance in the entire watershed was lower than what would have
been expected from theoretical numbers of smolts per km of useable rearing habitat
documented in other rivers (e.g., Bocking and Peacock 2005). We estimated a total
length of 158 km of stream that was 2nd, 3rd, or 4th order, sizes that are commonly used
for rearing by juvenile coho salmon. Our empirically based estimate of 37,424 smolts
represents a smolt yield of 237 smolts per km. By contrast, the 4-year average smolt
yield from an equivalent-sized river in Washington, the Clearwater, was nearly twice this
number, at 448 smolts per km, with an SD of 110 smolts per km (summarized in Bocking
and Peacock 2005). Similar production per km of stream from the Chuit River would
yield almost 71,000 smolts. Other systems monitored in Cook Inlet are not as
comparable in terms of habitat to the Chuit River; smolt abundances have been estimated
for the Moose River (Kenai River drainage) and Cottonwood Creek drainages, but these
systems differ from the Chuit River in that they each have extensive lake habitat. If there
were more coho smolts in the Chuit River system than the 37,424 estimated by the mark-
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recapture study in 2008, then our estimated proportion contributed from each of the three
study streams to the entire system was biased high (Table 10).
Our estimate of smolt abundance also appears low when considering likely numbers of
adult fish that return to this watershed. We cannot know how many adult fish the 2008
smolt run will produce but if we assume similar smolt production in 2007 as we saw in
2008, then this year’s return of about 5,000 adult fish in the three tributaries would
represent high marine survival rates. The three study streams appear to contribute about
50% of the Chuit smolt run. If we assume no commercial or sport fishery harvests and
double the adult return observed in these three tributaries from 5,000 to 10,000 fish,
37,000 smolts would have to experience a 27% marine survival rate. To account for
combined commercial and sport fishery exploitation rates of 20%, the estimate of marine
survival would exceed 32%. Such survival was reached only once in 20 annual estimates
(across three rivers combined) of marine survival from Cook Inlet summarized by
Lafferty et al. (2007).
It is possible however, that the Chuit River smolts exhibit unusually high survival rates.
Smolts from the study tributaries in 2008 included a high proportion of large fish (>120
mm), which we expect to have higher marine survival than smaller fish (e.g., Beamish et
al. 2004). Coho salmon smolts from the Kenai River also have a large proportion of body
sizes greater than 120 mm (R. Massengill, ADF&G, personal communication), and
survivals exceeded 20% in four of five years summarized by Lafferty et al (2007). In
Stream 2003, if we assume the smolt production of 7,790 smolts was similar to the 2007
smolt run, the 2007 smolt run would have had to have a marine survival rate of 26% to
yield a return of 2,000 adult coho salmon we estimated to have escaped to Stream 2003 in
2008 (assuming no fishery harvests). This seems unlikely, but could be more likely if
there are additional contributions from age-1 smolts (in 2007) to the adult return (in
2008).
There are at least two explanations for what may be an underestimate of smolts from the
entire Chuit watershed; these explanations could be acting singularly or in combination.
These sources of bias (described below) would reduce the estimated contribution of
salmon by Stream 2003 to the entire Chuit River, but probably not substantially (e.g., to
15-18% from the 21% estimated here).
First, there was almost certainly some number of smolts downstream from the RSTs that
were never vulnerable to the capture gear and were not included in the population
estimate. This lowest eight miles of river represents about 8% of the total Chuit River
stream habitat and has relatively high flow, low gradient stream reaches that could be
high quality habitat for overwintering of coho salmon before they smolt. Conservatively,
it seems plausible that this habitat contains 10% or more of the watershed’s smolts, but
that were not counted in the smolt abundance estimate of 37,000. If another 4,000 smolts
existed in this lower reach, it would drop the contribution of Stream 2003 from 20.7% to
18.8% of the Chuit River abundance.
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Second, our estimate is based primarily on age-2 fish; as noted above, age-1 fish likely
contribute to some degree to the smolt production from this system. Although coho runs
are predominantly from age-2 smolts in Cook Inlet, age-1 coho have contributed from
20% (Kenai River) to 50% of the run (Cottonwood Creek) in some years (unpublished
data from ADF&G). If 20% of the Chuit River smolt run was from age-1 fish in 2008,
then the true smolt abundance for the Chuit River watershed would have been
approximately 45,000 fish. Even if another 10% were added to this to account for
production below the RSTs, Stream 2003 would still have contributed 15.7% (7,790 of
49,500) of the smolts produced in the Chuit River in 2008.
5.4 Abundance of Chinook Salmon Smolts in Tributary Streams Versus the Chuit
River Watershed
Too few Chinook salmon smolts were detected in the tributaries to generate an
abundance estimate for the Chuit River watershed. Although we documented the
movement of adult Chinook salmon into the tributary streams, we saw relatively few
juvenile Chinook salmon moving downstream, out of these systems (either as smolts or
pre-smolts). One explanation for this scarcity of juvenile Chinook salmon is that these
fish normally have low densities in the tributaries, and instead use the mainstem river for
most juvenile rearing. In this case, juvenile fish that hatch in the tributaries, upstream of
the weirs, would have migrated downstream either at too small of a size to be captured in
the weir mesh (e.g., age-0), or early in the season, before the weirs were fully operational
and most other fish were moving. Relative to coho salmon, Chinook salmon are known
to have a greater tendency to use larger or mainstem river habitat for rearing (Healey
1991), a tendency that may have been reinforced by the high densities of juvenile coho
salmon in our study streams. In field surveys in 2006 and 2007, Oasis (2008) also found
that densities of juvenile Chinook salmon were relatively low in streams 2002, 2003, and
2004, accounting for only 0 to 1% of the fish captured.
An alternative explanation for the low numbers of juvenile Chinook salmon detected in
the tributaries could have been misidentification by field crews; such mistakes can be
easy between Chinook and coho salmon, especially where one species is plentiful and the
other is scarce. Our crews, however, were aware of this potential from the outset, and
were able to distinguish the species at the rotary screw traps in the mainstem river. In
addition, we verified the identification of challenging specimens early in the season using
genetic testing; although some fish could have been mistakenly identified as coho salmon
early in the season, it would not have accounted for the obvious absence of Chinook
salmon seen among all three systems.
One final explanation for the scarcity of juvenile Chinook salmon in the study tributaries
is simply that it was an unusually poor year for production, either because of low
numbers of returning adults in the parent year or because of low survival rates of eggs or
fry. This alternative will be addressed by monitoring in future years.
Relatively more Chinook salmon smolts were captured in the mainstem river, using the
rotary screw traps. Observations of low numbers in the tributary streams and somewhat
higher numbers in the mainstem river are confounded by use of different gear types, but
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are also consistent with results from surveys conducted by Oasis (2008) in 2006 and
2007. As noted above, juvenile Chinook salmon accounted for only 0 to 1% of the total
catch in minnow traps placed in the tributaries, but accounted for 6 to 13% of the catch in
the mainstem river (Oasis 2008). These surveys also noted that catch composition of
Chinook salmon declined from May and June to September (Oasis 2008), a decline
consistent with the declining CPUE over time observed in our study in 2008 (Figure 26).
5.5 Overwintering of Stream 2003 by Resident Fish Species
This objective was originally meant to be addressed by assessing winter behavior of large
rainbow trout (or Dolly Varden) tagged with radio transmitters. As stated above, we did
not tag any fish with radio transmitters in 2008. Instead, we operated the weirs through
the middle (Stream 2002) or end of September (streams 2003 and 2004) to see if we
could infer any winter patterns from weir catches from the early spring through the late
fall, then match these results to data that Oasis Environmental was in the process of
analyzing from the prior winter (Oasis 2009).
As described in the Results, we saw relatively low numbers of large (>100 mm) rainbow
trout in all three study tributaries in 2008. Stream 2003 differed from the other study
streams in that there was a net movement downstream (out of the system) on the video
cameras (Table 12), and it had the fewest rainbow trout captured in the weirs (Table 4).
We did see a small group (n=7) of larger rainbow trout migrate through the partial weir
maintained on Stream 2003 in late May (Figures 10 and 33). These fish likely had
overwintered in Stream 2003; otherwise they would have had to migrate upstream from
the Chuit River in mid May, at a time when water levels were rising and the water
temperatures were relatively cold (<2 °C). Such upstream movement would seem
unlikely. Thereafter, rainbow trout detected in the late spring or summer could have
originated from either direction (upstream from Stream 2003, or downstream from the
Chuit River). We had been prepared to see an obvious movement of large rainbow trout
upstream into the tributaries in the fall, when the adult coho salmon returned (because
rainbow trout are known to feed on the eggs of spawning salmon); this influx was not
detected on Stream 2003, was relatively small (compared to summer movements) in
Stream 2002, and was similar to peak summer movements Stream 2004 (Figure 10).
Crews also walked Stream 2003 downstream of the weir numerous days in September
and did not see any obvious congregations of rainbow trout. It is possible that adult
rainbow trout could still have moved into the tributaries in October, after the weirs were
removed. Field crews from Oasis Environmental did not detect rainbow trout in Stream
2003 via hook and line sampling in September of 2007 (Oasis 2009), providing some
supporting evidence that abundances are relatively low in the late fall on this stream.
Large (>100 mm) Dolly Varden char had an overall net movement upstream past the
video cameras on all three study streams in 2008 (Table 12). There was a notable
downstream movement of Dolly Varden into the partial weir on Stream 2003 in late May;
as with the fewer numbers of rainbow trout at this time, our opinion is that these fish had
most likely overwintered in Stream 2003. We did not have weirs in place on streams
2002 or 2004 at this time, and the weir in place on Stream 2002 earlier (May 2 through
12) caught no fish. In the fall, we saw another notable downstream movement of large
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2008 Chuit River Fisheries Monitoring Report – Final Report
Dolly Varden in September from streams 2002 and 2004, but not from Stream 2003
(Figure 31). There were more Dolly Varden detected moving upstream in September
than there had been rainbow trout, but this upstream movement of Dolly Varden still
represented a general decrease from the summer (Appendices G, H, and I).
Overall, the best indicator of overwinter use of Stream 2003 from our study came from
the combination of life stage and calendar date for species moving downstream past the
weir in 2008. Juvenile coho salmon smolts and limited numbers of juvenile Chinook
salmon obviously had overwintered in the tributaries, and the Dolly Varden and rainbow
trout captured in late May probably had also done so.
Arctic lamprey may also have overwintered in streams 2002 and 2003, based on the
general evidence from run timing and size in 2008. Arctic lamprey are generally thought
to migrate to sea in the fall and return to spawn in the spring, but are also known to have
a resident (non-anadromous) form (Mecklenburg et al. 2002). In streams 2002 and 2003,
the distinct group of Arctic lamprey migrating downstream in June had probably
overwintered in the streams because few were detected moving upstream past the camera
on Stream 2002, and because Stream 2003 would have been blocked to upstream passage
from May 27 to June 27. Alternative explanations were that these lamprey moving
downstream in June were ones that had migrated upstream in early spring, before the
weirs were installed, and were now migrating back to sea. Such behavior would mean
these lamprey were iteroparous (repeat spawners), which appears to be rare
(http://www.fishbase.org/). Field crews documented adult Arctic lamprey spawning in
Stream 2002 in July, further supporting the explanation that the ones migrating in June
were immature adults migrating seaward, and that had thus overwintered in the
tributaries.
6.0 Conclusions and Summary of Key Results
The important conclusions from the fish monitoring study in 2008 were that the overall
design and approach was effective for estimating the proportion of coho salmon smolts in
the study tributaries relative to the entire watershed, and for obtaining the data needed to
monitor potential changes in coho salmon production in Stream 2003. The study
provided information needed to complete baseline studies (2008) and begin the first year
of the predevelopment monitoring period (2008-2011). This information includes a rich
assortment of data on the timing and magnitude of fish movements into and out of the
three tributary streams, basic biological characteristics of the fish species collected, the
abundance of coho salmon relative to the Chuit River watershed, and indicators of which
species and life stages likely overwinter in the tributaries. The key results related to each
objective are summarized below.
6.1 Objective 1: Describe the Movement and Abundance of Fish Moving Into and
Out of Streams 2002, 2003, and 2004
The abundance and timing of numerous fish species moving to and from streams 2002,
2003, and 2004 were described thoroughly from late spring through mid fall in 2008.
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2008 Chuit River Fisheries Monitoring Report – Final Report
Movement between the tributaries and mainstem Chuit River was dominated by juvenile
coho salmon, many of which were moving in the course of smolting as they prepared to
migrate to sea. Some of this dominance was due to the capture methods, which were
designed for migratory fish such as coho and not for fish with less pronounced seasonal
migrations (e.g., sculpin). Nevertheless, the work in 2008 showed that coho salmon are a
large part of the species assemblage in each system, and constitute the majority of the
salmon produced in each. Far fewer juvenile Chinook salmon were documented (less
than 1% of fish detected from all streams combined). Total fish catch and total species
number in each tributary decreased from downstream to upstream in the watershed.
The species found in each stream were generally consistent with prior studies conducted
for the original EIS and for the SEIS, except that adult sockeye salmon were documented
in each study tributary in 2008. The relative abundance of some species, however,
differed from previous studies. We saw more adult coho salmon and fewer adult
Chinook salmon moving upstream into the tributaries than had been documented in past
studies. The numbers of lamprey, primarily Arctic lamprey, moving downstream in
streams 2002 and 2003 exceeded numbers suggested from past studies, likely because
previous methods (primarily minnow traps) were less effective at targeting this species.
The biological data from 2008 also supports most suggestions from earlier studies
regarding the basic life histories of fish in the system, especially the age at migration of
juvenile coho salmon.
6.2 Objective 2: Describe the Effects of Development on Stream 2003 on Production
of Chinook and Coho Salmon Smolts
The study in 2008 made good progress towards generating an annual time series of coho
and Chinook salmon smolt abundance during the predevelopment period (2008 through
2011), designed as part of the approach to the ASCMCRA permitting process. The smolt
runs in both streams 2003 and 2004 were able to be monitored with weirs, yielding the
first year of data for this objective. Most importantly, it shows that the BACI design
meant to address Objective 2 is feasible from a field monitoring standpoint.
6.3 Objective 3: Estimate the Proportion of Fish Produced within the Chuit River
Watershed that is Contributed by Stream 2003
The proportion of coho salmon produced by Stream 2003 relative to the Chuit River
watershed during 2008 was given a point estimate of 20.8%, based strictly on the markrecapture methods. This is likely a maximum number because it accounts for all the coho
salmon smolts in the tributaries, but not in the mainstem river (e.g., smolts already
downstream of the recapture site, or age-1 smolts in the mainstem river that were
excluded from the population estimate). These factors could realistically drop the coho
smolt contribution from Stream 2003 to the Chuit River to a range of approximately 15%
to 19%. The number of Chinook salmon captured in the study streams was too low to
calculate a statistically viable abundance estimate for the watershed; this low number
appeared to be due to a true absence of fish in the tributaries and not to any sampling
difficulties.
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2008 Chuit River Fisheries Monitoring Report – Final Report
6.4 Objective 4: Describe Overwintering Use of Stream 2003 by Resident Rainbow
Trout or Dolly Varden Char
The same monitoring and biological descriptions conducted under Objective 1 also gave
some insights into overwintering by groups of fish. When combined with observations
from winter sampling conducted by Oasis Environmental (Oasis 2009), this information
should be useful for assessing likely overwintering of fish in Stream 2003. Based on the
species, ages, and likely maturity stages of fish caught exiting the tributaries in May and
June and entering the tributaries in September, it appears that the fish that overwinter in
the tributaries are juvenile coho salmon (two age classes), Arctic lamprey (at least
ammocoetes, and possibly mature fish), juvenile Chinook salmon, sculpin (two species),
rainbow trout, and Dolly Varden char.
The overwintering rainbow trout and Dolly Varden include at least two age classes of
immature fish, based on the size, timing, and movement direction in the lower tributaries.
Based on downstream movements in late May and early June, some adult rainbow trout
and Dolly Varden char may also overwinter in the tributaries. We did not see a large
upstream movement of these adults into the tributaries in September, suggesting that any
overwintering adults either move in a distinct pulse in October (after our study had
ended), or that they represent a smaller portion of the group seen moving into and out of
the tributaries throughout the summer. Sampling by Oasis Environmental during the
previous October did not detect any distinct upstream movement of rainbow trout (Oasis
2009).
7.0 Acknowledgements
The Alaska Department of Fish and Game, the Environmental Protection Agency, the
National Marine Fisheries Service, and the U.S. Fish and Wildlife Service provided
helpful comments on the study design. T. Arndt, J. Beland, S. Brennan, S. Crawford, K.
Christie, T. Dann, D. Hauser, J. Hendrickson, R. Kirchner, J. Konsor, S. McKendrick, A.
Marsh, C. McConnell, R. Rodrigues, E. Sjoden, and C. Ziolkowski (all with LGL)
assisted with field work. Video system design, acquisition, installation, and training was
provided by B. Nass of LGL. G. Wade (LGL) provided GIS support and created the
maps in this report.
Overall study support was provided by R. Stiles of DRven Corporation, and by J. Lucas
and D. Graham of PacRim Coal, LP. Logistical support was provided by C. Rock, M.
Paulic, V. Isotova, J. Walls, M. Cunningham, and R. Freeman and Threemile Creek
Services (Beluga, AK). Air support was provided by Pathfinder Aviation (Homer, AK),
M. Spernak & Spernak Air (Anchorage, AK), Everts Air Cargo (Anchorage, AK), and
Northern Pioneer (Big Lake, AK). Technical support was provided by R. Bochenek and
S. St. Clair at Axiom Consulting and Design (Anchorage, AK). Scale analysis was
provided by Carol Lidstone at Birkenhead Scale Analysis (Lone Butte, B.C.). V. Priebe
at Happy Computer Services (Wasilla, AK) helped with document production and C.
Herlugson (Cougar Mountain Environment, Rio Rancho, NM) provided reviews of the
report.
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2008 Chuit River Fisheries Monitoring Report – Final Report
A special thanks goes to the members of the communities of Beluga and Tyonek, Alaska,
who provided logistics, lodging, and local knowledge and planning.
The study was funded by PacRim Coal, LP.
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2008 Chuit River Fisheries Monitoring Report – Final Report
Table 1. Summary statistics for the Chuit River and study
subdrainages. Historical flow data from RTI (2007).
1
2
Stream
3
2003
36.9
2
30
4
Chuit River
2002
2004
2
Watershed area (km )
139.4
55.4
38.4
5
Stream order
4
3
2
Length (km)
103
39
33
3
Mean flow m /s
April
8.7
1.0
1.2
0.5
30.0
4.3
3.0
4.1
May
20.1
0.9
0.9
0.9
June
5.1
0.5
0.3
0.3
July
7.5
1.3
0.6
0.8
August
15.9
2.9
1.7
2.5
September
10.1
1.2
1.0
0.9
Total annual
1
Data from Station C230, 3.2 river km downstream of Stream 2002
2
Data from Station C220, at confluence with Chuit River
3
Data from Station C180, at confluence with Chuit River
4
Data from Station C110, at confluence with Chuit River
5
From Strahler (1957)
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2008 Chuit River Fisheries Monitoring Report – Final Report
Table 2. Locations and operating dates of sampling sites and camps in the Chuit River
watershed, May through September, 2008. WGS84 datum.
Location
Stream 2002
Weir
Dates of
operation
Number of days
Latitude Longitude SampledAvailable
May 3 - May 12/ 61.12633 151.30415
Jun 4 - Sep 19
Fyke net
May 13 - Jun 9
61.12575 151.30359
Minnow trap 18
Minnow traps 19 and 20
Minnow trap 21
Minnow trap 22
Minnow trap 23
Minnow trap 24
Minnow trap 25
Minnow trap 26
Minnow trap 27
Minnow trap 28
May 24 - 25
May 23 - 24
May 23 - 25
May 24 - 25
May 24 - 25
May 23 - 24
May 23 - 24
May 23 - 24
May 24 - 25
May 23 - 24
61.12594
61.12592
61.12573
61.12570
61.12518
61.12507
61.12503
61.12535
61.12526
61.12538
Camp
111
118
151.30348
151.30339
151.30350
151.30356
151.30295
151.30273
151.30275
151.30225
151.30235
151.30251
61.12771 151.30199
Stream 2003
Weir
May 4 - Sep 30
61.12908 151.32979
147
150
Stream 2004
Weir
Jun 8 - Sep 30
61.15707 151.44278
96
115
Camp
61.15251 151.44841
Stream 200401 (fyke net) Jun 29 - Sep 3
61.15186 151.44899
65
65
Chuit River
Rotary screw trap (RST1) May 12 - Sep 13 61.10175 151.19365
Rotary screw trap (RST2) May 14 - Sep 3 61.10188 151.18002
123
111
125
113
Fyke net
May 26 - Jun 6 / 61.10073 151.19418
Jul 2 - 17
Minnow traps 1, 2 and 3
Minnow trap 4
Minnow traps 5 and 6
May 25 - 29
May 25 - 29
May 25 - 29
LGL Alaska Research Associates, Inc.
61.10073 151.19418
61.10083 151.19342
61.10040 151.19037
64
Stream 2002 Stream 2003
Species
Scientific name
Number % Number %
307 2
226
1
Arctic lamprey
Lampetra camtschatica
5 0
7
0
Chinook salmon (a) Oncorhynchus tshawytscha
169 1
11
0
Chinook salmon (j)
Oncorhynchus tshawytscha
0
Chum salmon (a)
Oncorhynchus keta
16 0
7
0
Coastrange sculpin
Cottus aleuticus
4 0
4
0
Coho salmon (a)
Oncorhynchus kisutch
14,897 94 18,698 97
Coho salmon (j)
Oncorhynchus kisutch
64 0
124
1
Dolly Varden
Salvelinus malma
17 0
6
0
Lamprey spp. (a)
Petromyzontidae spp.
Lamprey spp. (j)
206 1
65
0
Petromyzontidae spp.
2 0
Ninespine stickleback Pungitius pungitius
6 0
Pacific lamprey
Lampetra tridentata
15 0
3
0
Pink salmon (a)
Oncorhynchus gorbuscha
1 0
Pink salmon (j)
Oncorhynchus gorbuscha
77
0
37
0
Rainbow trout
Oncorhynchus mykiss
11 0
11
0
Sculpin spp.
Cottidae spp.
41 0
16
0
Slimy sculpin
Cottus cognatus
0
Sockeye salmon (a) Oncorhynchus nerka
0
Sockeye salmon (j)
Oncorhynchus nerka
8
0
Threespine stickleback Gasterosteus aculeatus
7 0
1
0
Unidentified
Total
15,853 100 19,216 100
Stream
Stream 2004
200401
Chuit River
Number % Number % Number %
7
0
272
2
20
0
3
0
26
0
4
0
3,027 20
1
0
5
0
62
0
49
1
419
3
1
0
4
0
22,682 98
2,212 43
9,530 64
137
1
16
0
114
1
0
20
0
673
5
17
0
2
0
0
18
0
128
1
210
1
2,783 55
509
3
5
0
4
0
10
0
26
0
25
0
126
1
1
0
1
0
1
0
15
0
70
0
4
0
23,199 100
5,093 100 14,947 100
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
Table 3. Fish caught moving downstream and percent of catch by species and location in the Chuit River drainage, May
through September, 2008. Data include all gear types except video. (a) = adult, (j) = juvenile.
65
2002
Weir Fyke MT
302
5
5
169
Species
Arctic lamprey
Chinook salmon (a)
Chinook salmon (j)
Chum salmon (j)
Coastrange sculpin
14
Coho salmon (a)
4
14,879
Coho salmon (j)
Dolly Varden
62
Lamprey spp. (a)
17
205
Lamprey spp. (j)
Ninespine stickleback
2
Pacific lamprey
6
Pink salmon (a)
15
Pink salmon (j)
Rainbow trout
71
Sculpin spp.
6
Slimy sculpin
20
Sockeye salmon (a)
Sockeye salmon (j)
Threespine stickleback
7
Unidentified
7
Total
15,791
2
13
2
1
1
6
5
21
1
57
2003
Weir
226
7
11
Total
307
5
169
0
16
7
4
4
5 14,897 18,698
64
124
17
6
206
65
2
6
15
3
1
77
37
11
11
41
16
0
0
8
7
1
5 15,853 19,216
2004
Weir Fyke Total
7
7
20
20
26
4
30
1
1
62
49
111
1
1
22,682 2,212 24,894
137
16
153
0
20
20
0
0
0
0
210 2,783 2,993
5
4
9
26
25
51
1
1
1
1
0
0
23,199 5,093 28,292
RST1
199
1
1,688
2
160
3
6,251
58
462
13
2
10
93
310
3
61
6
30
3
9,355
Chuit River
Fyke MT RST2 Total
30
43
272
2
3
62 12 1,265 3,027
3
5
98
161
419
1
4
135
7 3,137 9,530
3
5
48
114
0
1
210
673
4
17
2
8
18
35
128
13
2 184
509
2
5
10
16
49
126
1
1
9
15
13
27
70
1
4
373 26 5,193 14,947
Grand
Total
812
35
3,237
6
553
13
68,019
455
23
964
19
8
36
129
3,616
41
234
2
16
78
12
78,308
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
Table 4. Fish catch by location and gear type. Weir = weir, Fyke = fyke net, MT = minnow trap, RST = rotary screw trap. Not all
gear types were used at all locations. The fyke net listed under 2004 was on side tributary # 200401. a = adult, j = juvenile.
66
2008 Chuit River Fisheries Monitoring Report – Final Report
Table 5. Species richness, diversity, and evenness from all sampling sites in the Chuit
River drainage, May through September, 2008.
Sampling group
All sites, weirs and rotary screw traps
Stream 2002
Stream 2003
Stream 2004
Chuit River
Total
S
H'
Hmax
J'
11
8
9
13
13
0.25
0.14
0.14
1.04
0.43
2.40
2.08
2.20
2.56
2.56
0.10
0.07
0.06
0.41
0.17
Stream 200401 fyke net
6
0.79
1.79
0.44
Note: S = Species richness; H' = Shannon-Wiener index of diversity (-pi[lnpi]); Hmax
= ln(s); J' = Pielou's estimate of species evenness (H'/Hmax).
LGL Alaska Research Associates, Inc.
67
2008 Chuit River Fisheries Monitoring Report – Final Report
Table 6. Number of fish, by species or group, and their direction of travel as
observed in the video chute or from shore-based visual counts in Stream 2002, from
June 8 through September 29, 2008. Movement was estimated by a combination of
complete hourly counts and expanded 15 minute subsamples.
Species
Chinook salmon (adult)
Coho salmon (adult)
Sockeye salmon (adult)
Chum salmon (adult)
Pink salmon (adult)
Unknown adult salmon
Up
341
2,882
12
4
436
4
Video
Down Undefined
124
0
567
0
0
0
0
0
204
0
20
0
Visual
Up
Down
0
0
21
0
0
0
0
0
0
0
0
0
Salmon smolt (>100 mm)
Salmon fingerling (45-100 mm)
Salmon fry (<45 mm)
594
338
0
6,464
44
0
48
0
0
0
0
0
0
0
0
Rainbow trout (>100 mm)
Rainbow trout (45-100 mm)
316
17
224
10
1
5
0
0
0
0
Dolly Varden (>100 mm)
Dolly Varden (45-100 mm)
440
4
168
0
0
0
0
0
0
0
0
5
8
72
0
3
0
0
0
0
41
4
3
0
0
8
48
5,489
32
5
7,946
0
0
60
0
0
21
0
0
0
Lamprey spp. (>100 mm)
Lamprey spp. (<100 mm)
Sculpin spp.
Unknown adult fish
Unknown juvenile fish
Total
LGL Alaska Research Associates, Inc.
68
2008 Chuit River Fisheries Monitoring Report – Final Report
Table 7. Number of fish, by species or group, and their direction of travel as
observed in the video chute or from shore-based visual counts in Stream 2003, from
June 29 through September 30, 2008. Movement was estimated by a combination of
complete hourly counts and expanded 15 minute subsamples.
Species
Chinook salmon (adult)
Coho salmon (adult)
Sockeye salmon (adult)
Chum salmon (adult)
Pink salmon (adult)
Unknown adult salmon
Up
80
1,782
24
0
4
8
Video
Down Undefined
59
1
324
0
0
0
0
0
3
0
21
0
Visual
Up
Down
0
0
531
6
0
0
0
0
0
0
10
0
Salmon smolt (>100 mm)
Salmon fingerling (45-100 mm)
Salmon fry (<45 mm)
156
936
632
396
688
576
28
264
232
0
0
0
0
0
0
Rainbow trout (>100 mm)
Rainbow trout (45-100 mm)
99
140
172
116
0
0
0
0
0
0
Dolly Varden (>100 mm)
Dolly Varden (45-100 mm)
306
8
160
4
1
0
0
0
0
0
Lamprey spp. (>100 mm)
Lamprey spp. (<100 mm)
1
0
9
52
0
4
0
0
0
0
Sculpin spp.
0
4
0
0
0
23
70
4,269
27
27
2,638
0
12
542
0
0
541
0
0
6
Unknown adult fish
Unknown juvenile fish
Total
LGL Alaska Research Associates, Inc.
69
2008 Chuit River Fisheries Monitoring Report – Final Report
Table 8. Number of fish, by species or group, and their direction of travel as
observed in the video chute or from shore-based visual counts in Stream 2004, from
June 29 through September 29, 2008. Movement was estimated by a combination of
complete hourly counts and expanded 15 minute subsamples.
Video
Down Undefined
76
0
456
0
48
0
Visual
Up
Down
0
0
26
1
2
0
0
0
0
0
27
0
Species
Chinook salmon (adult)
Coho salmon (adult)
Sockeye salmon (adult)
Chum salmon (adult)
Pink salmon (adult)
Unknown adult salmon
Up
153
700
44
72
44
0
Salmon smolt (>100 mm)
Salmon fingerling (45-100 mm)
Salmon fry (<45 mm)
56
300
4
856
1,012
8
32
132
12
0
0
0
0
0
0
Rainbow trout (>100 mm)
Rainbow trout (45-100 mm)
340
20
302
136
3
32
0
0
0
0
Dolly Varden (>100 mm)
Dolly Varden (45-100 mm)
406
16
217
24
4
0
0
0
0
0
Lamprey spp. (>100 mm)
Lamprey spp. (<100 mm)
0
0
0
4
4
0
0
0
0
0
Sculpin spp.
8
4
4
0
0
28
54
2,201
40
100
3,327
0
4
227
0
0
55
0
0
1
Unknown adult fish
Unknown juvenile fish
Total
LGL Alaska Research Associates, Inc.
70
Species
Arctic lamprey
Chinook salmon (a)
Chinook salmon (j)
Chum salmon (j)
Coastrange sculpin
Coho salmon (a)
Coho salmon (j)
Dolly Varden
Lamprey spp. (a)
Lamprey spp. (ammocoete)
Ninespine stickleback
Pacific lamprey
Pink salmon (a)
Pink salmon (j)
Rainbow trout
Sculpin spp.
Slimy sculpin
Sockeye salmon (a)
Sockeye salmon (j)
Threespine stickleback
Unknown
Mean
152
454
65
44
64
496
71
155
129
113
43
430
387
34
73
51
63
520
39
53
43
Length (mm)
Min
Max
SD
55
505
43.3
280
855
197.2
25
231
24.4
24
94
25.2
20
114
13.7
359
590
84.2
27
272
29.3
36
350
55.0
115
150
10.8
17
222
33.0
29
60
10.4
145
530
125.8
265
524
46.4
26
38
2.0
20
470
59.4
15
104
21.9
26
114
13.7
495
545
35.4
33
54
4.6
17
87
25.5
26
75
18.6
n
811
34
3,119
6
509
7
17,248
452
21
957
18
8
34
128
1,378
36
233
2
16
76
5
Mean
11.0
Weight (g)
Min
Max
0.5
361.0
SD
40.9
n
104
4.7
0.5
111.0
6.1
499
4.0
0.5
19.5
3.0
124
5.6
51.8
3.2
2.3
1.4
205.0
0
2.0
1.0
0.5
0.5
205.0
77
462.5
6.0
6.0
3.5
205.0
7.8
77.9
1.3
1.3
1.1
2,394
87
15
187
7
1
0.6
31.0
3.5
3.2
0.5
0.5
0.1
0.5
1.0
691.0
9.5
10.0
0.2
74.2
3.0
2.2
11
124
15
33
0.5
3.6
0.5
0.5
0.5
0.5
0.5
7.5
0.5
0
2.4
0
7
14
3
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
Table 9. Mean length and weight for all species sampled from the Chuit River watershed, May through September, 2008. All
gear types and sites are combined. (a) = adult, (j) = juvenile.
71
2008 Chuit River Fisheries Monitoring Report – Final Report
Table 10. Number of coho salmon smolt observed in streams 2002, 2003, and 2004, and
their percent contribution to watershed-wide abundance estimates. Data are from June 1st
through July 19th, 2008. Fish from weirs were seperated into four size classes to
correspond with stratifications used for watershed-wide population estimates. Counts
from video include unidentified salmon greater than 100 mm. These salmon were
counted as coho salmon based on the size and catch proportions from the live boxes at the
weirs.
Catch
Weirs (80-89 mm)
Weirs (90-117 mm)
Weirs (117-161 mm)
Weirs >161 mm
Size and stream-specific estimates
2002
2003
2004
Total
317
357
306
980
962
4,686
2,143
7,791
1,189
2,310
1,460
4,959
44
41
176
261
Video (>100 mm)
6,367
396
856
7,619
Total coho salmon smolt
Percent contribution of
stream estimate to Chuit
abundance estimate
8,878
7,790
4,941
21,609
23.7%
20.8%
13.2%
57.7%
a
Chuit-wide
abundance
estimate
5,500
22,011
9,913
N/A
37,424a
Total system abundance estimate is based on mark-recapture data.
LGL Alaska Research Associates, Inc.
72
Species
Arctic lamprey
Chinook salmon (a)
Chinook salmon (j)
Chum salmon (j)
Coastrange sculpin
Coho salmon (a)
Coho salmon (j)
Dolly Varden
Lamprey spp. (a)
Lamprey spp. (ammocoete)
Ninespine stickleback
Pink salmon (a)
Pink salmon (j)
Pacific lamprey
Rainbow trout
Sculpin spp.
Slimy sculpin
Sockeye salmon (a)
Sockeye salmon (j)
Threespine stickleback
Unknown
May
June
Mean SD n Mean SD
145 24.0 24 152 44.6
59 20.9 381
38 2.8
2
67 15.4 31
66
144
128
95
49
21.3 350
20.1 89
12.3 15
34.5 170
10.8
5
65 30.1
52 37.2
69 15.2
99 30.3
125 33.2
130 6.7
121 29.3
33 1.9
46
35
1.8
182 92.7
62 17.2
62 11.6
19
11
35
131 91.7
47 26.7
60 11.1
38 1.6
56 14.8
37 1.4
4
4
2
41 7.2
71 14.0
34 10.6
n Mean
544 149
572
1425
67
3
32
19
65
507
4579
64
102 141
6
404 113
55
379
78
35
415
114
70
3
57
50
65
495
5
42
19
76
2
75
Grand
July
August
September
mean
SD n Mean SD n Mean SD n
41 185 184 49 14 157 40 44 152
202 14 372 150 20
454
20 846
65 11 430 71 7.4
37
65
1
44
12 165
62 14 160 65 15 134
64
83
3 535 78
2 440 114
2 496
25 6212
56 15 5037 59 16 1070
71
58 42 186 62 134 159 63 85 155
129
30 291 122 45 29 101 37 63 113
6.4
2
34 5.3
5 41 8.8
6
43
27 10 390 53 24
387
1.7
4
34
129
7 530
1
430
45 511
58 50 646 95 61 88
73
22 13
38 16.0
5 25 10.0
4
51
16 71
61 14 41 63 12 36
63
1
545
1 520
1
33
1
39
9.0 22
25 7.6 28 31 6.4
3
53
1
43
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
Table 11. Mean length for each species sampled from the Chuit River watershed, from May through September, 2008. All
gear types and sites are combined. All lengths are in millimeters (mm). (a) = adult, (j) = juvenile.
73
2008 Chuit River Fisheries Monitoring Report – Final Report
Table 12. Counts of fish movement, by species and direction, from the video
chutes and from shore-based visual observations during flooding events at each of
the weirs in the Chuit River drainage. Ranges were estimated by a combination of
complete hourly counts and expanded 15 minute subsample counts. Negative
numbers indicate downstream movement.
Species
Chinook salmon (adult)
Coho salmon (adult)
Sockeye salmon (adult)
Chum salmon (adult)
Pink salmon (adult)
Stream 2002
1
217 to 341
2,336 to 2,903
12
4
232 to 436
Stream 2003
2
Stream 2004
3
21 to 80
1,983 to 2,313
24
0
1 to 4
77 to 153
269 to 726
6 to 50
0
0
Salmon smolt (>100 mm)
-6,099 to -6,693
Salmon fingerling (45-100 mm) 236 to 338
Salmon fry (<45 mm)
0
-240 to -396
248 to 936
56 to 632
-744 to -800
-412 to -712
-4 to -8
Rainbow trout (>100 mm)
Rainbow trout (45-100 mm)
92 to 316
7 to 17
-73 to -172
24 to 140
38 to 340
-116 to -136
Dolly Varden (>100 mm)
Dolly Varden (45-100 mm)
272 to 440
4
146 to 306
4 to 8
189 to 406
-8 to -24
Lamprey spp. (>100 mm)
Lamprey spp. (<100 mm)
-8
-67 to -72
-8 to -9
-52
0
-4
-4
4 to 8
Sculpin spp.
37 to 41
Operational June 8 through September 19
2
Operational June 29 through September 30
3
Operational June 29 through September 29
1
LGL Alaska Research Associates, Inc.
74
2008 Chuit River Fisheries Monitoring Report – Final Report
Table 13. Coho salmon marked releases and recaptures by time period and length
group in the Chuit River, May through September, 2008. Darkly shaded cells were
excluded from any abundance estimates; lightly shaded cells represent time period
strata that were pooled for input into a Darroch model.
Length
group
80-89 mm
Length
group
90-117 mm
Length
group
118-161 mm
Release
Number
period
released (n1)
1
460
2
141
3
1,266
4
380
Number examined (n2)
Recapture periods
1
2
3
8
7
6
1
38
149
70
98
Release
Number
period
released (n1)
1
7,155
2
529
3
254
4
118
Number examined (n2)
Recapture periods
1
2
3
142
31
29
9
5
Release
Number
period
released (n1)
1
4,182
2
126
3
46
4
Number examined (n2)
Recapture periods
1
2
3
26
2
7
4
2
LGL Alaska Research Associates, Inc.
338
53
236
57
61
31
4
10
10
219
4
8
7
98
4
0
0
2
75
2008 Chuit River Fisheries Monitoring Report – Final Report
Table 14. Coho salmon smolt abundance estimates from the Chuit River,
2008. Estimates were calculated with either a pooled Petersen estimate or a
partially stratified estimate using the Darroch model. The shaded model is
the best estimate, as described in text.
N
5,500
SE
1,255
95% CI
Lower
Upper
3,041
7,959
Darroch
Pooled Peterson
22,011
25,490
1,180
1,361
19,698
22,822
24,324
28,157
118-161 mm Darroch
Pooled Peterson
9,913
15,061
1,230
1,924
7,503
11,290
12,323
18,831
Darroch + Peterson
37,424
2,116
33,276
Pooled Peterson
46,051
2,670
40,818
1
This Peterson estimate only includes the earliest release group.
41,572
51,283
Length group Estimate method
1
Peterson
80-90 mm
90-117 mm
80-161 mm
LGL Alaska Research Associates, Inc.
1
76
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
Figure 1. Map of the Chuit River drainage, showing the study tributaries in relation to the surrounding area.
77
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
Figure 2. Location of fish sampling sites in the Chuit River drainage including the fyke net located in Stream
200401.
78
2008 Chuit River Fisheries Monitoring Report – Final Report
Discharge (cfs)
1,000
900
800
700
600
500
400
300
200
100
0
1-Apr-2002
1-Apr-2004 1-Apr-2005 1-Apr-2006
Date
Figure 3. Historic daily discharge (cfs) for Stream 2003 (Station C180) from
April 2002 through October 2006. Stream 2003 is the only tributary that has
continuous data. Data are from RTI (2007).
Stream 2002
Stream 2003
Stream 2004
Discharge (cfs)
1,000
900
800
700
600
500
400
300
200
100
0
1-Apr
1-Apr-2003
1-May
1-Jun
1-Jul
1-Aug
1-Sep
1-Oct
1-Nov
Date
Figure 4. Historic daily discharge (cfs) for Streams 2002, 2003, and 2004, from
April through October, 2006 (Stations C220, C180, and C110). The year 2006
was the only period of record with overlap among all three streams. Data are
from RTI (2007).
LGL Alaska Research Associates, Inc.
79
Partially fishing
Overflowing (weirs only)
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
Not fishing
Fully functional
Stream
2002
1/6/1900
Stream
2003
1/5/1900
1/4/1900
Stream
2004
1/3/1900
Stream
200401
1/2/1900
RST1
RST2
1/1/1900
May0 3
30 1
June
60 1
July
90 1
Aug
120 1
Sep
150
Figure 5. Gear operation status for all sampling sites in the Chuit River drainage, from May through September, 2008.
Sites include the main sampling gear types only, not ancillary gear. When gear was not fishing, the gear was not
installed or unable to fish due to other conditions (high water events). The gear was partially fishing when either it was
fully functional for part of a day or partially functional for a whole day (hole or missing panel). Overflowing occurred
when weir panels were overtopped by water and were often still fish tight for upstream migrating salmon. When the
gear was fully functional it was operating normally and fish tight.
80
Effort (hours)
2008 Chuit River Fisheries Monitoring Report – Final Report
Stream 2002
24
18
12
6
0
3-May
28-May
22-Jun
24
18
12
6
0
3-May
28-May
22-Jun
24
18
12
6
0
3-May
24
18
12
6
0
3-May
24
18
12
6
0
3-May
24
18
12
6
0
3-May
17-Jul
11-Aug
Stream 2003
17-Jul
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
Stream 2004
28-May
22-Jun
17-Jul
Stream 200401
28-May
22-Jun
17-Jul
RST1
28-May
22-Jun
17-Jul
RST2
28-May
17-Jul
11-Aug
5-Sep
30-Sep
Date
Figure 6. Gear effort in hours each day for all sampling sites, from May through
September, 2008. Sites include only main gear types, not ancillary gear. Stream
200401 is included as one of the main sites because it enters below the weir on
Stream 2004.
LGL Alaska Research Associates, Inc.
22-Jun
81
Stream 2002
Stream 2003
2,400
Stream 2004
Stream 200401
CPUE (fish/day)
2,000
Chuit River
1,600
1,200
800
400
0
3-May 18-May
2-Jun
17-Jun
2-Jul
17-Jul
1-Aug
16-Aug 31-Aug 15-Sep
30-Sep
Date
Figure 7. Catch per unit effort (CPUE) for all fish caught in the study tributaries and mainstem Chuit River, from May
through September, 2008. Data are from weirs, RSTs, and the fyke net on Stream 200401 only.
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
2,800
82
2008 Chuit River Fisheries Monitoring Report – Final Report
Stream 2002
3,000
2,500
2,000
≥ 90 mm
< 90 mm
Discharge
250
200
1,500
150
1,000
100
500
50
0
3-May 17-May 31-May 14-Jun
3,000
0
28-Jun
12-Jul
26-Jul
300
Stream 2003
2,500
250
2,000
200
1,500
150
1,000
100
500
50
0
3-May 17-May 31-May 14-Jun
3,000
2,500
0
28-Jun
12-Jul
26-Jul
300
Stream 2004
250
2,000
200
1,500
150
1,000
100
500
0
3-May 17-May 31-May 14-Jun
Discharge (cfs)
CPUE (fish/day)
300
50
0
28-Jun
12-Jul
26-Jul
Date
Figure 8. Catch per unit effort (CPUE) and mean daily discharge (cfs) for two
size classes of juvenile coho salmon in the study tributaries May through July,
2008. Fish ≥ 90 mm were considered smolts; fish < 90 mm were considered presmolts. Data are preliminary from RTI (Ft. Collins, CO). Discharge data not
available for May on Stream 2004, or August and September for all study
tributaries.
LGL Alaska Research Associates, Inc.
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2,500
2,000
CPUE (fish/day)
1,500
1,000
500
0
3-May
3,000
2,500
2,000
1,500
1,000
500
0
3-May
7-Jun
12-Jul
16-Aug
20-Sep
Stream 2003
7-Jun
12-Jul
16-Aug
Stream 2004
3,000
16
14
12
10
8
6
4
2
0
2,500
2,000
1,500
1,000
500
0
3-May
7-Jun
12-Jul
16-Aug
≥ 90 mm Chuit River
3,000
> 90 mm
2,500
Temperature
2,000
1,500
1,000
500
0
3-May
7-Jun
12-Jul 16-Aug
Date
20-Sep
16
14
12
10
8
6
4
2
0
20-Sep
16
14
12
10
8
6
4
2
0
20-Sep
Figure 9. Catch per unit effort (CPUE) and mean daily water temperature (°C) from RTI (Fort Collins, CO) for
two size classes of juvenile coho salmon in the study tributaries and mainstem Chuit River, May through
September, 2008. Fish ≥ 90 mm were considered smolts; fish < 90 mm were considered pre-smolts.
2008 Chuit River Fisheries Monitoring Report – Final Report
16
14
12
10
8
6
4
2
0
Temperature (°C)
LGL Alaska Research Associates, Inc.
Stream 2002
3,000
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12
Stream 2002
Weir
Video
8
4
0
-4
-8
Movement (fish/day)
-12
14-May
12
14-Jun
14-Jul
Stream 2003
14-Aug
14-Sep
14-Jun
14-Jul
Stream 2004
14-Aug
14-Sep
Jun-14
Jul-14
Aug-14
Sep-14
8
4
0
-4
-8
-12
14-May
12
8
4
0
-4
-8
-12
May-14
Date
Figure 10. Daily movement of rainbow trout (>100 mm) in each of the tributaries,
from July through September, 2008. Movement includes both catch at the weirs
(downstream movement) and video counts (upsteam or downstream). Negative
counts show downstream movements. Does not include data from Stream 200401.
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40
Stream 2002
30
20
Weir
Video
10
0
-10
-20
-30
Movement (fish/day)
-40
40
14-May
14-Jun
Stream 200314-Aug
14-Jul
14-Jun
14-Jul
14-Aug
Stream 2004
14-Sep
14-Jun
14-Jul
Date
14-Sep
14-Sep
30
20
10
0
-10
-20
-30
-40
14-May
40
30
20
10
0
-10
-20
-30
-40
14-May
14-Aug
Figure 11. Daily movement of Dolly Varden (>100 mm) in each of the
tributaries, from May through September, 2008. Movement includes both
catch at the weirs (downstream movement) and video counts (upstream or
downstream). Negative counts show downstream movements. Does not
include data from Stream 200401.
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500
age-0
400
300
200
100
0
4-May
1-Jun
CPUE (fish/day)
500
29-Jun
27-Jul
24-Aug
21-Sep
27-Jul
24-Aug
21-Sep
29-Jun
27-Jul
Date
24-Aug
21-Sep
age-1
400
300
200
100
0
4-May
1-Jun
500
29-Jun
age-2
400
300
200
100
0
4-May
1-Jun
Figure 12. CPUE by week for all three age classes of juvenile coho salmon
migrating from Stream 2002 in 2008. Catch by age was determined by
applying a ratio of fish caught per age group per week, then expanding it to
total catch by week. Age data were only taken for fish greater than 60 mm.
Data from weirs only.
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700
age-0
600
500
400
300
200
100
0
4-May
1-Jun
700
27-Jul
24-Aug
21-Sep
27-Jul
24-Aug
21-Sep
27-Jul
24-Aug
21-Sep
age-1
600
CPUE (fish/day)
29-Jun
500
400
300
200
100
0
700
4-May
1-Jun
29-Jun
age-2
600
500
400
300
200
100
0
4-May
1-Jun
29-Jun
Date
Figure 13. CPUE by week for all three age classes of juvenile coho salmon
migrating from Stream 2003 in 2008. Catch by age was determined by
applying a ratio of fish caught per age group per week, then expanding it to
total catch by week. Age data were only taken for fish greater than 60 mm.
Data from weirs only.
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age-0
400
300
200
100
0
4-May
1-Jun
27-Jul
24-Aug
21-Sep
27-Jul
24-Aug
21-Sep
27-Jul
24-Aug
21-Sep
age-1
400
CPUE (fish/day)
29-Jun
300
200
100
0
4-May
1-Jun
29-Jun
age-2
400
300
200
100
0
4-May
1-Jun
29-Jun
Date
Figure 14. CPUE by week for all three age classes of juvenile coho salmon
migrating from Stream 2004 in 2008. Catch by age was determined by
applying a ratio of fish caught per age group per week, then expanding it to
total catch by week. Age data were only taken for fish greater than 60 mm.
Data from weirs only.
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age-0
300
200
100
0
4-May
1-Jun
29-Jun
27-Jul
24-Aug
21-Sep
27-Jul
24-Aug
21-Sep
age-1
CPUE (fish/day)
300
200
100
0
4-May
1-Jun
29-Jun
age-2
300
200
100
0
4-May
1-Jun
27-Jul
24-Aug
21-Sep
Date
Figure 15. CPUE by week for all three age classes of juvenile coho salmon
in the mainstem Chuit River in 2008. Catch by age was determined by
applying a ratio of fish caught per age group per week, then expanding it to
total catch by week. Age data were only taken for fish greater than 60 mm.
LGL Alaska Research Associates, Inc.
29-Jun
90
2008 Chuit River Fisheries Monitoring Report – Final Report
300
Chuit River
250
Tributaries
Length (mm)
200
150
100
50
0
3-May
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
Date
Figure 16. Juvenile coho salmon lengths (fork lengths) by date observed from the
study tributaries and the Chuit River, May through September, 2008. Data from all
gear types.
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140
Stream 2002
Stream 2003
120
Stream 2004
100
Relative Weight (Wr)
LGL Alaska Research Associates, Inc.
Chuit River
80
60
40
20
0
0
50
100
150
200
250
Length (mm)
Figure 17. Relative weight by length for juvenile coho salmon caught at all sites, from May through September,
2008. Does not include fish caught in Stream 200401. Fish below 80 mm are excluded. The horizontal line shows
the relative weight of fish with healthy body condition (100).
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3,000
Stream 2002
≥ 90 mm
2,000
< 90 mm
1,000
0
3-May
28-May
3,000
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
Stream 2003
2,000
CPUE (fish/day)
1,000
0
3-May
28-May
3,000
22-Jun
17-Jul
Stream 2004
2,000
1,000
0
3-May
1,000
800
600
400
200
0
3-May
1,000
800
600
400
200
0
3-May
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
Stream 200401
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
Chuit River
28-May
22-Jun
17-Jul
Date
11-Aug
5-Sep
30-Sep
Figure 18. Juvenile coho salmon catch per unit effort (CPUE) by location and
size group, from May through September, 2008. Data are only for the primary
gear type for a given location.
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140
Juvenile Chinook salmon
120
Chuit River
Stream 2002
Stream 2003
Stream 2004
100
80
60
140
Juvenile coho salmon
120
Relative Weight (Wr)
100
80
60
140
Dolly Varden
120
100
80
60
140
Rainbow trout
120
100
80
60
3-May
24-May
14-Jun
5-Jul
26-Jul
16-Aug
6-Sep
Figure 19. Mean relative weight (Wr) by week for juvenile Chinook salmon, juvenile
coho salmon, Dolly Varden, and rainbow trout caught at all sampling sites. Does not
include fish caught in Stream 200401. Sampling was from May through September,
2008. The horizontal line shows the relative weight of fish with healthy body condition
(100).
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Juvenile Chinook salmon
140
120
Chuit River
Stream 2002
Stream 2003
Stream 2004
100
80
60
0
50
100
200
250
300
350
400
450
300
350
400
450
300
350
400
450
Dolly Varden
140
Relative Weight (Wr)
150
120
100
80
60
0
50
100
150
200
250
Rainbow trout
140
120
100
80
60
0
50
100
150
200
250
Length (mm)
Figure 20. Relative weight (Wr) by length (mm) of juvenile Chinook salmon, Dolly
Varden, and rainbow trout caught at all sampling sites from May through September,
2008. Does not include fish caught in Stream 200401. Fish below 80 mm are
excluded. The horizontal line shows the relative weight of fish with healthy body
condition (100).
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40
30
20
10
0
3-May
CPUE (fish/day)
40
30
20
10
0
3-May
40
30
20
10
0
3-May
40
30
20
10
0
3-May
40
30
20
10
0
3-May
Stream 2002
28-May
22-Jun
17-Jul
≥ 175 mm
< 175 mm
11-Aug
5-Sep
30-Sep
5-Sep
30-Sep
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
Stream 2003
28-May
22-Jun
17-Jul
11-Aug
Stream 2004
28-May
22-Jun
17-Jul
11-Aug
Stream 200401
28-May
22-Jun
17-Jul
Chuit River
28-May
22-Jun
17-Jul
Date
Figure 21. Arctic lamprey catch per unit effort (CPUE) by location and size group,
from May through September, 2008. Data are only for the primary gear type for a
given location.
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Stream 2002
30
300
250
200
150
100
50
0
≥ 175 mm
< 175 mm
Discharge
20
10
0
3-May
17-May 31-May
14-Jun
12-Jul
26-Jul
Stream 2003
30
300
250
200
20
150
100
10
50
0
3-May
Discharge (cfs)
CPUE (fish/day)
28-Jun
0
17-May 31-May
14-Jun
28-Jun
12-Jul
26-Jul
Stream 2004
30
300
250
200
20
150
100
10
50
0
3-May
0
17-May 31-May
14-Jun
28-Jun
12-Jul
26-Jul
Date
Figure 22. Catch per unit effort (CPUE) and mean daily discharge (cfs) for two size
classes of Arctic lamprey in the study tributaries from May through July, 2008. Size
break was placed at 175 mm to differentiate between sub-adults and potentially
mature individuals. Data are preliminary from RTI (Ft. Collins, CO). Discharge data
not available for May on Stream 2004, or August and September for all study
tributaries.
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CPUE (fish/day)
16
14
12
10
8
6
4
2
0
l
ay
ay
Jun 7-Ju -Aug 5-Sep 0-Sep
1
3-M 28-M 223
11
35
30
25
20
15
10
5
0
Stream 2003
35
30
25
20
15
10
5
0
Stream 2004
≥ 175 mm
< 175 mm
Temperature
16
14
12
10
8
6
4
2
0
l
ay
ay
Jun 7-Ju -Aug 5-Sep 0-Sep
1
3-M 28-M 223
11
16
14
12
10
8
6
4
2
0
35
30
25
20
15
10
5
0
Chuit River
16
14
12
10
8
6
4
2
0
l
ay
ay
Jun 7-Ju -Aug 5-Sep 0-Sep
1
3-M 28-M 223
11
l
g
p
p
ay May -Jun
-Ju -Au 5-Se 0-Se
M
7
2
1
3
2
3
11
28
Date
Figure 23. Catch per unit effort (CPUE) and mean daily water temperature (°C) for two size classes of Arctic lamprey in
the study tributaries and the mainstem Chuit River, from May through September, 2008. Size break was placed at 175 mm
to differentiate between sub-adults and potentially mature individuals.
2008 Chuit River Fisheries Monitoring Report – Final Report
Stream 2002
Temperature (°C)
LGL Alaska Research Associates, Inc.
35
30
25
20
15
10
5
0
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Arctic lamprey
600
Chuit River
500
Tributaries
400
300
200
100
0
3-May
28-May
Length (mm)
600
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
5-Sep
30-Sep
Pacific lamprey
500
400
300
200
100
0
3-May
28-May
600
22-Jun
17-Jul
Lamprey ammocoete
500
400
300
200
100
0
3-May
28-May
22-Jun
17-Jul
11-Aug
Date
Figure 24. Arctic lamprey, Pacific lamprey, and lamprey ammocoete lengths by date
observed on the study tributaries and Chuit River, May through September, 2008.
Data are from all gear types.
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Coho salmon
900
750
600
450
300
150
0
3-May
28-May
22-Jun
11-Aug
5-Sep
30-Sep
Chinook salmon
900
Length (mm)
17-Jul
750
Stream 2002
600
Stream 2003
450
Stream 2004
300
150
0
3-May
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
Pink salmon
900
750
600
450
300
150
0
3-May
28-May
22-Jun
17-Jul
Date
Figure 25. Adult coho, Chinook, and pink salmon lengths (mid eye to fork of tail) by
date on study tributaries, May through September, 2008. Data are from weirs only.
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Stream 2002
60
≥ 65 mm
< 65 mm
40
20
0
3-May
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
Stream 2003
60
40
20
CPUE (fish/day)
0
3-May
28-May
22-Jun
60
17-Jul
Stream 2004
40
20
0
3-May
28-May
22-Jun
17-Jul
Stream 200401
60
40
20
0
3-May
60
40
20
0
3-May
28-May
22-Jun
17-Jul
Chuit River
28-May
22-Jun
17-Jul
Date
Figure 26. Juvenile Chinook salmon catch per unit effort (CPUE) by location and
size group, May through September, 2008. Data are only for the primary gear type
for a given location.
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250
200
Chuit River
Tributaries
Length (mm)
150
100
50
0
3-May
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
Date
Figure 27. Juvenile Chinook salmon lengths (fork lengths) by date observed on study
tributaries and Chuit River, May through September, 2008. Data are from all gear
types.
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100
Chum salmon
80
Chuit River
Tributaries
60
40
20
0
3-May
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
5-Sep
30-Sep
Pink salmon
100
Length (mm)
80
60
40
20
0
3-May
28-May
22-Jun
17-Jul
Sockeye salmon
100
80
60
40
20
0
3-May
28-May
22-Jun
17-Jul
11-Aug
Date
Figure 28. Juvenile chum, pink, and sockeye salmon lengths (fork length) by date
observed on the study tributaries and Chuit River, May through September, 2008.
Data are from all gear types.
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Coastrange sculpin
120
100
80
60
40
20
0
3-May
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
5-Sep
30-Sep
Slimy sculpin
120
Length (mm)
100
80
60
40
20
0
3-May
28-May
22-Jun
120
17-Jul
11-Aug
Cottidae spp.
100
Chuit River
Tributaries
80
60
40
20
0
3-May
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
Date
Figure 29. Coastrange sculpin, slimy sculpin, and unidentified sculpin species total
lengths by date observed on the study tributaries and Chuit River, May through
September, 2008. Data are from all gear types.
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30
300
Stream 2002
250
≥ 100 mm
< 100 mm
Discharge
20
200
150
10
100
50
0
17-May 31-May
30
14-Jun
28-Jun
12-Jul
26-Jul
300
250
200
150
100
50
0
Stream 2003
20
10
0
3-May
17-May 31-May
30
14-Jun
28-Jun
12-Jul
Discharge (cfs)
CPUE (fish/day)
0
3-May
26-Jul
300
Stream 2004
250
200
20
150
10
100
50
0
3-May
0
17-May 31-May
14-Jun
28-Jun
12-Jul
26-Jul
Date
Figure 30. Catch per unit effort (CPUE) and mean daily discharge (cfs) for two
size classes of Dolly Varden in the study tributaries, May through July, 2008.
Size break was placed at 100 mm to differentiate between obvious juveniles and
potentially mature individuals. Data are preliminary from RTI (Ft. Collins,
CO). Discharge data not available for May on Stream 2004 and in August and
September for all sites.
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30
20
10
0
3-May
30
20
10
0
3-May
Stream 2002
< 100 mm
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
5-Sep
30-Sep
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
Stream 2003
28-May
22-Jun
17-Jul
11-Aug
Stream 2004
30
CPUE (fish/day)
≥ 100 mm
20
10
0
3-May
28-May
22-Jun
17-Jul
11-Aug
Stream 200401
30
20
10
0
3-May
30
20
10
0
3-May
28-May
22-Jun
17-Jul
Chuit River
28-May
22-Jun
17-Jul
Date
Figure 31. Dolly Varden catch per unit effort (CPUE) by location and size group,
May through September, 2008. Data are only for the primary gear type for a given
location.
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CPUE (fish/day)
Stream 2003
Date
Figure 32. Catch per unit effort (CPUE) and mean daily water temperature (°C) for two size classes of Dolly Varden in the
study tributaries and mainstem Chuit River, from May through September, 2008. Size break was placed at 100 mm to
differentiate between obvious juveniles and potentially mature individuals.
2008 Chuit River Fisheries Monitoring Report – Final Report
Chuit River
16 30
16
14
14
12
12
20
10
10 20
8
≥ 100 mm
8
6
6
< 100 mm
10
10
4
4
Temperature
2
2
0
0
0
0
3-May 28-May 22-Jun 17-Jul 11-Aug 5-Sep 30-Sep 3-May 28-May 22-Jun 17-Jul 11-Aug 5-Sep 30-Sep
30
Temperature (°C)
LGL Alaska Research Associates, Inc.
Stream 2002
Stream 2004
16
16 30
14
14
12
12
20
10
10 20
8
8
6
6 10
10
4
4
2
2
0
0
0
0
3-May 28-May 22-Jun 17-Jul 11-Aug 5-Sep 30-Sep 3-May 28-May 22-Jun 17-Jul 11-Aug 5-Sep 30-Sep
30
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Dolly Varden
500
Chuit River
400
Tributaries
300
200
Length (mm)
100
0
3-May
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
5-Sep
30-Sep
Rainbow trout
500
400
300
200
100
0
3-May
28-May
22-Jun
17-Jul
11-Aug
Date
Figure 33. Dolly Varden and rainbow trout lengths (fork lengths) by date observed on
the study tributaries and Chuit River, from May through September, 2008. Data
include all gear types.
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Length (mm)
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100
90
80
70
60
50
40
30
20
10
0
3-May
100
90
80
70
60
50
40
30
20
10
0
3-May
Threespine stickleback
Chuit River
Tributaries
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
5-Sep
30-Sep
Ninespine stickleback
28-May
22-Jun
17-Jul
11-Aug
Date
Figure 34. Threespine and ninespine stickleback total lengths by date observed on the
study tributaries and Chuit River, May through September, 2008. Data are from all
gear types.
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20
15
10
5
0
3-May
CPUE (fish/day)
20
15
10
5
0
3-May
20
15
10
5
0
3-May
Stream 2002
28-May
22-Jun
17-Jul
11-Aug
≥ 100 mm
< 100 mm
5-Sep
30-Sep
5-Sep
30-Sep
5-Sep
30-Sep
Stream 2003
28-May
22-Jun
17-Jul
11-Aug
Stream 2004
28-May
22-Jun
17-Jul
11-Aug
Stream 200401
800
400
0
3-May
28-May
22-Jun
20
17-Jul
11-Aug
5-Sep
30-Sep
11-Aug
5-Sep
30-Sep
Chuit River
10
0
3-May
28-May
22-Jun
17-Jul
Date
Figure 35. Rainbow trout catch per unit effort (CPUE) by location and size group,
from May through September, 2008. Data are only for the primary gear type for a
given location.
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Stream 2002
10
300
≥ 100 mm
< 100 mm
Discharge
8
6
250
200
150
4
100
2
50
0
3-May 17-May 31-May 14-Jun
0
28-Jun
12-Jul
26-Jul
Stream 2003
10
300
250
CPUE (fish/day)
200
6
150
4
100
2
50
0
3-May
0
17-May 31-May 14-Jun
28-Jun
12-Jul
26-Jul
Stream 2004
10
Discharge (cfs)
8
300
250
8
200
6
150
4
100
2
50
0
3-May
0
17-May 31-May 14-Jun
28-Jun
12-Jul
26-Jul
Date
Figure 36. Catch per unit effort (CPUE) and mean daily discharge (cfs) for two
size classes of rainbow trout in the study tributaries, from May through July,
2008. A size break was placed at 100 mm to differentiate between obvious
juveniles and potentially mature individuals. Data are preliminary from RTI (Ft.
Collins, CO). Discharge data not available for May on Stream 2004, or in August
and September for all sites.
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CPUE (fish/day)
Chuit River
Stream 2003
16
16 20
14
14
12
12 15
15
10
10
≥ 100 mm
8
8 10
10
6
6
< 100 mm
4
5
4
5
Temperature
2
2
0
0
0
0
3-May 28-May 22-Jun 17-Jul 11-Aug 5-Sep 30-Sep
3-May 28-May 22-Jun 17-Jul 11-Aug 5-Sep 30-Sep
20
Date
Figure 37. Catch per unit effort (CPUE) and mean daily water temperature (°C) for two size classes of rainbow trout in the study
tributaries and mainstem Chuit River, May through September, 2008. Size break was placed at 100 mm to differentiate between
obvious juveniles and potentially mature individuals.
2008 Chuit River Fisheries Monitoring Report – Final Report
Stream 2004
16
14
12
15
10
8
10
6
5
4
2
0
0
3-May 28-May 22-Jun 17-Jul 11-Aug 5-Sep 30-Sep
20
Temperature (°C)
LGL Alaska Research Associates, Inc.
Stream 2002
16
14
12
15
10
8
10
6
5
4
2
0
0
3-May 28-May 22-Jun 17-Jul 11-Aug 5-Sep 30-Sep
20
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2008 Chuit River Fisheries Monitoring Report – Final Report
4000
3500
3000
Number of fish
2500
Stream 2004
Stream 2003
Stream 2002
2000
1500
1000
500
0
-500
-1000
1-Jul
16-Jul
15-Aug
30-Aug
14-Sep
29-Sep
Date
Figure 38. Upstream and downstream counts of adult coho salmon from video and visual
counts, at each of the three weirs in the Chuit River drainage, July through September,
2008. Movement was estimated by a combination of complete hourly counts and expanded
15 minute subsample counts. Negative counts show downstream movements.
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31-Jul
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100
80
Number of fish
60
Stream
2004
Stream
2004
Stream
2003
Stream
2003
Stream 2002
Stream 2002
40
20
0
-20
-40
-60
8-Jun
22-Jun
6-Jul
3-Aug 17-Aug 31-Aug 14-Sep
Date
Figure 39. The total expanded number of all adult Chinook salmon counted
moving through the video chute at the weirs on streams 2002, 2003, and 2004 in
the Chuit River drainage, June 8 through September 19, 2008. Negative bars
show downstream movement. No counts for Stream 2002 were compiled between
August 6 and August 22.
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20-Jul
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90
60
Stream 2002
Jack Chinook salmon
Adult Chinook salmon
30
0
-30
8-Jun
22-Jun
6-Jul
Number of fish
90
20-Jul
3-Aug 17-Aug 31-Aug 14-Sep
Stream 2003
60
30
0
-30
8-Jun
22-Jun
6-Jul
90
20-Jul
3-Aug 17-Aug 31-Aug 14-Sep
Stream 2004
60
30
0
-30
8-Jun
22-Jun
6-Jul
20-Jul
3-Aug 17-Aug 31-Aug 14-Sep
Date
Figure 40. The total expanded number of Chinook and jack Chinook salmon
counted moving through the video chute at the weirs on streams 2002, 2003, and
2004 in the Chuit River drainage, June 8 through September 19, 2008. Negative
bars show downstream movement. No counts for Stream 2002 were compiled
between August 6 and August 22.
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0.25
0.20
Relative frequency
LGL Alaska Research Associates, Inc.
0.30
0.15
0.10
0.05
0.00
0
1
2
3
4
5
6
7
8
9
10
Travel time (days)
Figure 41. Estimated travel time of marked juvenile coho salmon moving from weirs in the
tributary streams to RSTs in the mainstem Chuit River. Travel time was modeled with a
Poisson distribution based upon a constant rate of travel.
116
2008 Chuit River Fisheries Monitoring Report – Final Report
100%
90%
Cumulative Frequency
80%
70%
60%
Marked
50%
Recaptured
40%
30%
20%
10%
0%
80
90
100
120
130
140
150
160
170
Length
(
) of coho salmon lengths from fish
Figure 42. Cumulative frequency distribution
marked at the weirs and recaptured at the rotary screw traps from the Chuit
River in 2008. The upper limit of 161 mm and the vertical black line at 117 mm
are break points as identified by a Kolmogorov-Smirnov test.
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18
16
Temperature (°C)
14
Chuit River
Stream 2002
Stream 2003
Stream 2004
12
10
8
6
4
2
0
3-May
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
Date
Figure 43. Mean daily water temperatures at the four sampling locations in the
Chuit River watershed, May through September, 2008. Gaps in data series are when
temperatures were not recorded.
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118
Water temperature (˚C)
Stream 2002
ay May -Jun
Jul -Aug -Sep -Sep
M
7
2
5
1
3
2
30
11
28
18
16
14
12
10
8
6
4
2
0
Stream 2003
ay May -Jun
Jul -Aug -Sep -Sep
M
7
2
5
1
3
2
30
11
28
18
16
14
12
10
8
6
4
2
0
Stream 2004
l
ay May
ug
Jun 7-Ju
A
M
2
1
3
2
11
28
18
16
14
12
10
8
6
4
2
0
ep
ep
5-S 30-S
Chuit River
l
g
ay
ay
Jun 7-Ju
Au
1
1
3-M 28-M
221
ep
ep
5-S 30-S
Date
Figure 44. Daily average, minimum, and maximum water temperatures (˚C) at all four sampling sites in the Chuit
River watershed, May through September, 2008. Gaps in the data are when temperatures were not recorded.
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
18
16
14
12
10
8
6
4
2
0
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300
Stream 2002
Stream 2003
Stream 2004
Discharge (cfs)
250
200
150
100
50
0
1-May
16-May
31-May
15-Jun
Date
30-Jun
15-Jul
30-Jul
Figure 45. Mean daily discharge (cfs) at Streams 2002, 2003, and 2004, from May
1 through July 31, 2008. Discharge data are preliminary from RTI (Ft. Collins,
CO); data not available for Stream 2004 in May.
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4
Chuit River
Stream 2002
Stream 2003
Stream 2004
Standardized water depth
3
2
1
0
-1
-2
3-May
28-May
22-Jun
17-Jul
11-Aug
5-Sep
30-Sep
Date
Figure 46. Standardized water depths for the four sampling sites in the Chuit River
watershed, from May through September, 2008.
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Precipitation (cm)
2.5
2
1.5
1
0.5
0
1-May
1-Jun
1-Jul
1-Aug
1-Sep
1-Oct
Date
Figure 47. Daily precipitation (cm) from a weather gauging station on Stream 2004
within the Chuit River watershed, May through September, 2008. Precipitation data
are from McVehil-Monnett (unpublished).
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160
Age-1 coho salmon
Mainstem Chuit River
140
Tributaries
120
100
80
60
40
Length (mm)
20
0
2-May
1-Jun
1-Jul
31-Jul
30-Aug
29-Sep
30-Aug
29-Sep
Age-2 coho salmon
160
140
120
100
80
60
40
20
0
2-May
1-Jun
1-Jul
31-Jul
Date
Figure 48. Change in length over time for age-1 and age-2 for coho salmon in the
three study tributaries and mainstem Chuit River. Mean length is reported in 2week time periods; whiskers are standard deviation. Data for age-1 coho salmon
are for sample sizes ≥15 fish per week.
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123
Stream 2002 coho salmon age-2+
559
140
Catch (fish/week)
120
100
373
80
263
60
143
156
80 mm
85 mm
90 mm
95 mm
100 mm
105 mm
110 mm
115 mm
120 mm
125 mm
130 mm
135 mm
140 mm
145 mm
150 mm
155 mm
160 mm
165 mm
170 mm
40
20
0
0
28
29
0
23
24
25
26
27
Week
Figure 49. Emigration timing of 5-mm length classes of age 2+ coho salmon from Stream 2002 (weir data only), from June
1 through July 19, 2008. For each week (x-axis), the number of fish in each length class was estimated from scale ages and
expanded to the entire population. Numbers in the chart show the weekly sample sizes.
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
160
124
2551
700
Catch (fish/week)
600
500
400
2139
80mm
85mm
90mm
95mm
100mm
105mm
110mm
115mm
120mm
125mm
130mm
135mm
140mm
145mm
150mm
155mm
160mm
165mm
300
200
459
100
474
73
44
24
0
23
24
25
26
Week
27
28
29
Figure 50. Emigration timing of 5-mm length classes of age 2+ coho salmon from Stream 2003 (weir data only), from June
1 through July 19, 2008. For each week (x-axis), the number of fish in each length class was estimated from scale ages and
expanded to the entire population. Numbers in the chart show the weekly sample sizes.
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
Stream 2003 coho salmon age-2+
800
125
85mm
95mm
105mm
115mm
125mm
135mm
145mm
155mm
165mm
175mm
Catch (fish/week)
250
200
1059
150
90mm
100mm
110mm
120mm
130mm
140mm
150mm
160mm
170mm
100
166
401
159
50
34
0
24
25
26
Week
27
28
29
Figure 51. Emigration timing of 5-mm length classes of age 2+ coho salmon from Stream 2004 (weir data only), from June
8 through July 19, 2008. For each week (x-axis), the number of fish in each length class was estimated from scale ages and
expanded to the entire population. Numbers in the chart show the weekly sample sizes.
2008 Chuit River Fisheries Monitoring Report – Final Report
LGL Alaska Research Associates, Inc.
Stream 2004 coho salmon age-2+
1267
300
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2008 Chuit River Fisheries Monitoring Report – Final Report
Photo 1. The weir on Stream 2002 at low water levels, August 1, 2008.
The photo shows the “V” orientation with water flowing from the bottom
of the image to the top.
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Photo 2. The weir on Stream 2003 at low water levels,
August 1, 2008. The photo shows a nested “V”
formation, with water flowing from the top of the image
to the bottom. The top “V” fished at low water levels
and both “V’s” fished at high water levels (using a 2nd
holding box not shown).
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Photo 3. The weir on Stream 2004 at lower water levels,
September 11, 2008. The weir is in a “V” formation with
the water flowing from the top of the image to the bottom.
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Photo 4. The pipe that transferred fish from the weir to the holding box on
Stream 2003. Fish remained in the holding box (beneath a lid), until they
were processed. Water is flowing from the top of the image to the bottom.
Photo 5. The fyke net on Stream 200401 (tributary to Stream 2004) on
June 29, 2008. Photo is looking downstream.
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Photo 6. The downstream entrance to the underwater video chute,
electronics housing, and battery bank at the weir on Stream 2002. The top
of the photo is upstream.
Photo 7. The Stream 2003 ramp for adult salmon traveling upstream being
inspected on September 3, 2008. Water flow is from top right to bottom left.
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Photo 8. A rotary screw trap (RST) on the mainstem Chuit River. Water
is flowing from right to left. Fish were trapped by the opening of the large
cone facing upstream, and remained in the holding box (beneath open lid)
until they were processed.
Photo 9. The upstream rotary screw trap (RST1) fishing at high water
levels on the mainstem Chuit River, May 15, 2008. Photo is looking
downstream.
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Photo 10. The upstream rotary screw trap (RST1) fishing at low water
levels, August 5, 2008. Photo is looking downstream.
Photo 11. The downstream rotary screw trap (RST2) at high water levels
on the Chuit River, July 17, 2008. Photo is looking downstream. The
cone is raised to prevent damage from woody debris.
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Photo 12. The downstream rotary screw trap (RST2) at low water levels,
August 3, 2008. Photo is looking downstream.
Photo 13. A partial weir on Stream 2003 fishing during high water in
mid-May, 2008. Photo is looking upstream.
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Photo 14. The weir on Stream 2002 at high water levels, July 31,
2008. Water is flowing from the lower right to the upper left.
Photo 15. The full weir on Stream 2002 at low
water levels, July 3, 2008. Water is flowing
from the lower right to the upper left.
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Photo 16. The weir on Stream 2003 at low water levels, August 29,
2008. Water is flowing from the right corner to the left.
Photo 17. The weir on Stream 2003 at high water levels, September
20, 2008. During high water both the holding boxes were fishing.
Photo is looking downstream.
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Photo 18. The weir on Stream 2004 at low water levels, July 5,
2008. Photo is looking downstream.
Photo 19. The weir on Stream 2004 at high water levels, July 17,
2008. Photo is looking downstream.
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Photo 20. Coho salmon smolt captured on the mainstem Chuit River,
July 13, 2008.
Photo 21. Pacific lamprey captured on Stream 2002, July 3, 2008.
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Photo 22. Image series of two adult rainbow trout moving upstream
through the video chute on Stream 2002 in early June, 2008.
Photo 23. Adult sockeye salmon caught on Stream 2003, September 1,
2008.
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Appendix A. Gear operation status for all sampling sites in the Chuit River drainage,
from May through September, 2008. Sites include main gear types only. F = full
coverage and fish tight, O = water over the top of one or more panels (weirs only), P =
partial coverage or partially functinoal, N = gear not fishing, and - = gear not installed.
Stream
RST1
Date
Stream 2002 Stream 2003 Stream 2004
RST2
200401
3-May
P
4-May
P
P
5-May
P
P
6-May
P
P
7-May
P
P
8-May
P
P
9-May
P
P
10-May
P
P
11-May
P
P
12-May
P
P
P
13-May
P
F
14-May
P
F
P
15-May
P
F
F
16-May
P
P
P
17-May
P
P
P
18-May
P
P
F
19-May
P
P
F
20-May
P
F
F
21-May
P
F
F
22-May
P
P
P
23-May
P
F
P
24-May
P
P
F
25-May
P
P
F
26-May
P
F
F
27-May
P
F
P
28-May
P
F
F
29-May
O
F
F
30-May
O
F
F
31-May
F
P
F
1-Jun
F
F
F
2-Jun
F
F
F
3-Jun
F
F
F
4-Jun
P
O
F
F
5-Jun
O
O
F
F
6-Jun
O
F
P
P
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Appendix A- Continued. Gear operation status for all sampling sites.
Stream
Date
Stream 2002 Stream 2003 Stream 2004 2004-0101
7-Jun
O
F
8-Jun
O
F
P
9-Jun
F
F
P
10-Jun
F
F
P
11-Jun
F
F
P
12-Jun
F
F
F
13-Jun
F
F
F
14-Jun
F
F
F
15-Jun
F
F
F
16-Jun
F
F
F
17-Jun
F
F
F
18-Jun
F
F
F
19-Jun
F
F
F
20-Jun
F
F
F
21-Jun
F
F
F
22-Jun
F
F
F
23-Jun
F
F
F
24-Jun
F
F
F
25-Jun
F
F
F
26-Jun
F
F
P
27-Jun
F
F
F
28-Jun
F
F
F
29-Jun
F
F
F
P
30-Jun
F
F
F
F
1-Jul
F
F
F
F
2-Jul
F
F
P
F
3-Jul
F
F
F
F
4-Jul
F
F
F
F
5-Jul
F
F
F
F
6-Jul
F
F
F
F
7-Jul
F
F
F
F
8-Jul
F
F
F
F
9-Jul
F
F
F
F
10-Jul
F
F
F
F
11-Jul
F
F
F
F
12-Jul
F
F
F
F
13-Jul
F
F
F
F
LGL Alaska Research Associates, Inc.
RST1
P
F
F
F
F
P
F
P
P
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
P
F
F
F
F
F
F
F
F
P
P
RST2
P
F
F
F
F
F
F
P
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
P
F
F
F
P
F
F
F
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Appendix A- Continued. Gear operation status for all sampling sites.
Stream
Date
Stream 2002 Stream 2003 Stream 2004 2004-0101
14-Jul
F
F
F
F
15-Jul
F
F
F
F
16-Jul
F
F
F
F
17-Jul
O
O
O
P
18-Jul
F
F
F
19-Jul
F
F
F
P
20-Jul
F
F
F
F
21-Jul
F
F
F
F
22-Jul
F
F
F
F
23-Jul
F
O
F
F
24-Jul
O
O
O
P
25-Jul
O
P
F
P
26-Jul
O
P
F
F
27-Jul
O
O
O
P
28-Jul
O
O
F
29-Jul
P
O
F
P
30-Jul
F
F
P
F
31-Jul
F
F
F
F
1-Aug
F
F
F
F
2-Aug
P
F
F
F
3-Aug
F
F
F
F
4-Aug
F
F
F
F
5-Aug
F
F
F
F
6-Aug
F
F
F
F
7-Aug
F
F
F
F
8-Aug
F
F
F
F
9-Aug
F
F
F
F
10-Aug
F
F
F
F
11-Aug
F
F
F
F
12-Aug
F
F
F
F
13-Aug
F
F
F
F
14-Aug
F
F
F
F
15-Aug
P
F
F
F
16-Aug
F
F
F
F
17-Aug
P
F
F
F
18-Aug
F
F
F
F
19-Aug
P
F
F
F
20-Aug
F
P
F
F
21-Aug
F
F
F
F
LGL Alaska Research Associates, Inc.
RST1
F
F
P
P
F
F
F
P
P
F
P
F
F
F
F
F
F
F
F
F
F
F
F
F
P
F
F
F
F
F
F
F
F
F
F
F
F
F
F
RST2
P
F
F
P
P
F
F
F
F
F
P
P
F
P
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
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Appendix A- Continued. Gear operation status for all sampling sites.
Stream
Date
Stream 2002 Stream 2003 Stream 2004 2004-0101
22-Aug
P
F
F
F
23-Aug
F
F
F
F
24-Aug
P
F
F
F
25-Aug
F
F
F
F
26-Aug
F
F
F
F
27-Aug
F
F
F
F
28-Aug
F
F
F
F
29-Aug
F
F
F
F
30-Aug
P
F
F
F
31-Aug
F
F
F
F
1-Sep
F
F
P
F
2-Sep
F
F
F
F
3-Sep
O
O
O
P
4-Sep
O
O
F
5-Sep
O
O
F
6-Sep
O
O
F
7-Sep
P
O
P
8-Sep
O
O
F
9-Sep
O
P
N
10-Sep
N
P
P
11-Sep
P
P
P
12-Sep
P
O
P
13-Sep
P
P
N
14-Sep
N
P
N
15-Sep
N
N
N
16-Sep
N
P
N
17-Sep
N
N
N
18-Sep
N
N
N
19-Sep
N
O
N
20-Sep
O
N
21-Sep
O
N
22-Sep
P
N
23-Sep
P
N
24-Sep
O
N
25-Sep
O
N
26-Sep
O
N
27-Sep
O
N
28-Sep
O
N
29-Sep
O
N
30-Sep
P
N
LGL Alaska Research Associates, Inc.
RST1
P
N
P
F
F
F
F
F
P
N
P
F
F
P
P
F
P
F
P
P
F
F
P
-
RST2
P
N
P
F
F
F
P
F
P
N
P
F
P
-
143
2008 Chuit River Fisheries Monitoring Report – Final Report
Appendix B. The total actual and expanded numbers of salmon smolt recorded moving
through the video chute by direction in Stream 2002. Species identification was
assigned later, based on catch concurrent catch proportions through the weir (captured
in the holding box). Movement was estimated by a combination of complete hourly
counts and expanded 15 minute subsamples. No counts were compiled between August
6th and August 22nd.
Video-Actual
Video-Expanded
Date
Down
Up
Indeterminate
Down
Up
Indeterminate
8-Jun
4
0
2
4
0
2
9-Jun
31
0
0
31
0
0
10-Jun
14
2
0
14
2
0
11-Jun
98
29
0
98
29
0
12-Jun
167
0
0
167
0
0
14-Jun
76
13
0
76
13
0
15-Jun
55
16
2
55
16
2
16-Jun
25
2
0
25
2
0
17-Jun
70
6
0
214
6
0
18-Jun
75
13
8
300
52
32
19-Jun
97
0
0
388
0
0
20-Jun
105
5
0
420
20
12
21-Jun
100
2
0
400
8
0
22-Jun
87
0
0
348
0
0
23-Jun
9
0
0
36
0
0
24-Jun
158
0
0
632
0
0
25-Jun
41
2
164
8
0
26-Jun
203
0
0
812
0
0
27-Jun
268
0
0
1,072
0
0
28-Jun
44
0
0
176
0
0
29-Jun
1
0
0
4
0
0
30-Jun
61
26
0
244
104
0
1-Jul
22
52
0
88
208
0
2-Jul
10
0
0
40
0
0
3-Jul
66
0
0
264
0
0
4-Jul
4
0
0
16
0
0
5-Jul
69
0
0
276
0
0
6-Jul
7
0
0
28
0
0
9-Jul
1
0
0
4
0
0
10-Jul
1
0
0
4
0
0
11-Jul
1
0
0
4
0
0
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Appendix B- Continued. Total number of smolt counted moving through video chute
by direction at the weir on Stream 2002.
Video-Actual
Video-Expanded
Date
Down
Up
Indeterminate
Down
Up
Indeterminate
14-Jul
5
0
0
20
0
0
15-Jul
1
0
0
4
0
0
19-Jul
3
0
0
12
0
0
20-Jul
4
0
0
16
0
0
22-Jul
1
0
0
4
0
0
4-Aug
1
0
0
4
0
0
Total
1,985
168
LGL Alaska Research Associates, Inc.
15
6,464
468
48
145
2008 Chuit River Fisheries Monitoring Report – Final Report
Appendix C. The total actual and expanded numbers of smolt counted moving through
the video chute by direction in Stream 2003. Species identification was assigned later,
based on catch concurrent catch proportions through the weir (captured in the holding
box). Movement was estimated by a combination of complete hourly counts and
expanded 15 minute subsamples.
Video-Actual
Video-Expanded
Date
Down
Up
Indeterminate
Down
Up
Indeterminate
30-Jun
11
1
0
44
4
0
1-Jul
6
1
0
24
4
0
2-Jul
14
0
4
56
0
16
3-Jul
14
0
1
56
0
4
4-Jul
2
0
0
8
0
0
5-Jul
10
4
6
40
16
24
6-Jul
8
0
6
32
0
24
7-Jul
12
0
4
48
0
16
8-Jul
8
0
6
32
0
24
9-Jul
1
0
0
4
0
0
10-Jul
1
0
2
4
0
8
11-Jul
1
0
0
4
0
0
12-Jul
1
0
2
4
0
8
16-Jul
1
0
1
4
0
4
20-Jul
1
0
0
4
0
0
21-Jul
0
0
1
0
0
4
26-Jul
1
0
0
4
0
0
30-Jul
3
1
1
12
4
4
31-Jul
0
0
2
0
0
8
2-Aug
1
0
1
4
0
4
4-Aug
2
0
1
8
0
4
28-Aug
0
0
1
0
0
4
5-Sep
1
0
0
4
0
0
Total
99
7
39
396
28
156
LGL Alaska Research Associates, Inc.
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Appendix D. The total actual and expanded numbers of smolt counted moving through
the video chute by direction in Stream 2004. Species identification was assigned later,
based on catch concurrent catch proportions through the weir (captured in the holding
box). Movement was estimated by a combination of complete hourly counts and
expanded 15 minute subsample counts.
Video-Actual
Video-Expanded
Date
Down
Up
Indeterminate
Down
Up
Indeterminate
29-Jun
0
22
0
0
88
0
30-Jun
1
23
3
4
92
12
1-Jul
0
52
1
0
208
4
2-Jul
4
6
0
16
24
0
3-Jul
0
8
0
0
32
0
4-Jul
0
12
0
0
48
0
5-Jul
2
26
1
8
104
4
6-Jul
0
16
0
0
64
0
8-Jul
0
1
0
0
4
0
9-Jul
1
7
0
4
28
0
10-Jul
0
2
1
0
8
4
11-Jul
2
2
0
8
8
0
13-Jul
0
1
0
0
4
0
14-Jul
0
1
0
0
4
0
15-Jul
1
4
0
4
16
0
17-Jul
0
2
0
0
8
0
18-Jul
0
2
1
0
8
4
19-Jul
0
2
0
0
8
0
25-Jul
0
1
0
0
4
0
28-Aug
1
0
0
4
0
0
30-Aug
1
0
0
4
0
0
31-Aug
0
1
0
0
4
0
4-Sep
0
1
0
0
4
0
5-Sep
0
1
0
0
4
0
6-Sep
0
5
0
0
20
0
8-Sep
0
2
0
0
8
0
9-Sep
0
0
1
0
0
4
11-Sep
1
0
0
4
0
0
Total
14
200
8
56
800
32
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Appendix E. The total actual and expanded numbers of adult coho salmon counted
moving through the video chute, or counted visually at chute bypasses, in Stream
2002. Movement was estimated by a combination of complete hour counts and 15
minute subsample counts. No counts were compiled between August 6th and
August 22nd.
Video-Actual
Video-Expanded
Visual-Actual
Visual-Expanded
Date
Down
Up
Down
Up
Down
Up
Down
Up
24-Jul
0
25
0
100
0
0
0
0
25-Jul
2
1
8
4
0
0
0
0
26-Jul
5
2
20
8
0
0
0
0
27-Jul
1
1
4
4
0
0
0
0
28-Jul
0
2
0
8
0
0
0
0
29-Jul
0
3
0
12
0
0
0
0
30-Jul
4
1
16
4
0
0
0
0
31-Jul
1
1
4
4
0
0
0
0
1-Aug
0
1
0
4
0
0
0
0
2-Aug
0
1
0
4
0
0
0
0
3-Aug
0
2
0
8
0
0
0
0
6-Aug
0
1
0
4
0
0
0
0
3-Sep
0 1,702
0 1,753
0
0
0
0
4-Sep
470
18
479
18
0
0
0
0
5-Sep
3
3
12
12
0
0
0
0
6-Sep
0
1
0
4
0
0
0
0
7-Sep
1
607
4
622
0
0
0
0
8-Sep
1
0
4
0
0
0
0
0
9-Sep
0
193
0
205
0
0
0
0
10-Sep
0
2
0
8
0
0
0
0
11-Sep
0
2
0
8
0
0
0
0
12-Sep
1
3
4
12
0
0
0
0
13-Sep
0
3
0
12
0
0
0
0
14-Sep
0
6
0
24
0
2
0
2
15-Sep
0
3
0
12
0
10
0
10
16-Sep
3
1
12
4
0
1
0
1
17-Sep
0
3
0
12
0
6
0
6
18-Sep
0
3
0
12
0
2
0
2
Total
492 2,591
567 2,882
0
21
0
21
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Appendix F. The total actual and expanded numbers of adult coho salmon counted
moving through the video chute, or counted visually at chute bypasses, in Stream
2003. Movement was estimated by a combination of complete hour counts and 15
minute subsample counts.
Video-Actual
Video-Expanded
Visual-Actual
Visual-Expanded
Date
Down
Up
Down
Up
Down
Up
Down
Up
24-Jul
4
11
4
11
0
0
0
0
25-Jul
29
13
29
13
0
0
0
0
26-Jul
5
7
5
7
0
0
0
0
27-Jul
0
17
0
17
0
0
0
0
28-Jul
1
2
1
2
0
0
0
0
29-Jul
2
2
2
2
0
0
0
0
30-Jul
1
0
1
0
0
0
0
0
31-Jul
1
1
1
1
0
0
0
0
3-Aug
1
0
1
0
0
0
0
0
4-Aug
30
0
30
0
0
0
0
0
5-Aug
2
0
2
0
0
0
0
0
3-Sep
25
682
100 1,261
0
246
0
246
4-Sep
3
7
12
28
0
6
0
6
5-Sep
6
1
24
4
0
0
0
0
6-Sep
11
4
44
16
0
0
0
0
7-Sep
9
48
36
192
0
0
0
0
8-Sep
1
5
4
20
0
0
0
0
9-Sep
0
8
0
32
5
234
5
234
10-Sep
0
6
0
24
1
10
1
22
11-Sep
1
4
4
16
0
0
0
0
12-Sep
1
3
4
12
0
0
0
0
13-Sep
0
7
0
28
0
1
0
2
14-Sep
1
4
4
16
0
1
0
1
15-Sep
1
1
4
4
0
7
0
13
16-Sep
0
0
0
0
0
1
0
1
17-Sep
0
2
0
8
0
1
0
1
18-Sep
0
3
0
12
0
2
0
5
19-Sep
0
2
0
8
0
0
0
0
20-Sep
0
3
0
12
0
0
0
0
21-Sep
0
4
0
16
0
0
0
0
23-Sep
1
1
4
4
0
0
0
0
25-Sep
1
2
4
8
0
0
0
0
26-Sep
0
2
0
8
0
0
0
0
28-Sep
1
0
4
0
0
0
0
0
Total
138
852
324 1,782
6
509
6
531
LGL Alaska Research Associates, Inc.
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Appendix G. The total actual and expanded numbers of adult coho salmon counted
moving through the video chute, or counted visually at chute bypasses, in Stream
2004. Movement was estimated by a combination of complete hour counts and 15
minute subsample counts.
Video-Actual
Video-Expanded
Visual-Actual
Visual-Expanded
Date
Down
Up
Down
Up
Down
Up
Down
Up
3-Sep
4-Sep
5-Sep
6-Sep
7-Sep
8-Sep
9-Sep
10-Sep
11-Sep
12-Sep
13-Sep
14-Sep
15-Sep
16-Sep
17-Sep
18-Sep
19-Sep
20-Sep
21-Sep
22-Sep
23-Sep
24-Sep
25-Sep
26-Sep
27-Sep
28-Sep
Total
9
4
6
13
33
11
3
2
16
3
6
0
1
2
0
0
0
0
1
2
1
0
0
0
1
0
61
6
1
3
33
5
6
1
4
7
21
3
1
4
3
3
2
1
1
1
1
2
1
2
0
2
36
16
24
52
132
44
12
8
64
12
24
0
4
8
0
0
0
0
4
8
4
0
0
0
4
0
244
24
4
12
132
20
24
4
16
28
84
12
4
16
12
12
8
4
4
4
4
8
4
8
0
8
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
19
0
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
23
0
2
0
0
0
0
0
0
0
0
0
0
0
0
114
175
456
700
1
22
1
26
LGL Alaska Research Associates, Inc.
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Appendix H. Actual (unexpanded) numbers of fish passing through the video chute,
by direction, at the weir at Stream 2002 in the Chuit River drainage, June through
September, 2008. Movement was estimated by a combination of complete hour
counts and 15 minute subsample counts. No counts were compiled between August 6
and August 22.
Rainbow
Dolly
2
Chinook
Sockeye
Chum
Pink
trout
Varden
1
salmon
>100 mm
salmon
salmon
>100 mm
salmon
Up Down Up Down Up Down Up Down Up Down Up Down
Date
0
0
0
0
0
0
0
0
1
1
0
0
8-Jun
0
0
0
0
0
0
0
0
2
6
0
0
9-Jun
0
0
0
0
0
0
0
0
2
3
0
0
10-Jun
0
0
0
0
0
0
0
0
3
1
0
0
11-Jun
0
0
0
0
0
0
0
0
2
0
0
0
12-Jun
1
0
0
0
0
0
0
0
2
6
0
0
13-Jun
0
0
0
0
0
0
0
0
0
1
0
0
14-Jun
0
0
0
0
0
0
0
0
1
5
0
0
15-Jun
0
0
0
0
0
0
0
0
5
5
0
0
16-Jun
0
0
0
0
0
0
0
0
2
0
0
0
17-Jun
0
0
0
0
0
0
0
0
2
2
0
0
18-Jun
1
1
0
0
0
0
0
0
0
0
0
0
22-Jun
0
0
0
0
0
0
0
0
0
1
0
0
23-Jun
0
1
0
0
0
0
0
0
0
0
0
0
24-Jun
0
0
0
0
0
0
0
0
0
1
0
0
26-Jun
0
0
0
0
0
0
0
0
1
0
0
0
27-Jun
0
1
0
0
0
0
0
0
1
0
0
0
29-Jun
0
0
0
0
0
0
0
0
2
0
0
0
30-Jun
0
0
0
0
0
0
0
0
2
0
0
0
1-Jul
0
0
0
0
0
0
0
0
2
0
0
0
3-Jul
0
1
0
0
0
0
0
0
0
0
0
0
4-Jul
0
0
0
0
0
0
0
0
1
1
0
0
5-Jul
0
0
0
0
0
0
0
0
2
1
0
0
7-Jul
0
0
0
0
0
0
0
0
1
0
0
0
8-Jul
0
0
0
0
0
0
0
0
1
1
0
0
10-Jul
0
0
0
0
0
0
0
0
0
1
0
0
12-Jul
1
0
0
0
0
0
0
0
0
0
0
0
16-Jul
0
0
0
0
0
0
0
1
1
0
0
0
17-Jul
3
1
0
0
0
0
2
1
3
0
0
0
18-Jul
1
2
0
0
0
0
1
0
0
1
0
0
19-Jul
1
0
0
0
0
0
0
0
0
1
0
0
20-Jul
0
2
0
0
0
0
0
0
1
0
0
0
21-Jul
LGL Alaska Research Associates, Inc.
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Appendix H- Continued. Salmon Trout 2002.
Date
22-Jul
23-Jul
24-Jul
25-Jul
26-Jul
27-Jul
28-Jul
29-Jul
30-Jul
31-Jul
1-Aug
2-Aug
3-Aug
4-Aug
5-Aug
6-Aug
7-Aug
22-Aug
23-Aug
24-Aug
25-Aug
26-Aug
27-Aug
28-Aug
29-Aug
30-Aug
31-Aug
1-Sep
2-Sep
3-Sep
4-Sep
5-Sep
6-Sep
7-Sep
8-Sep
9-Sep
Chinook
salmon1
Up Down
0
1
3
1
19
0
1
1
3
1
1
1
3
0
5
1
2
0
4
0
5
2
6
2
14
3
5
4
5
4
0
1
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Chum
salmon
Up Down
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
LGL Alaska Research Associates, Inc.
Sockeye
salmon
Up Down
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
Pink
salmon
Up Down
0
0
1
0
12
0
3
2
1
5
19
0
6
1
9
9
4
5
5
5
7
8
3
3
12
0
5
5
7
2
1
0
2
4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Rainbow
trout2
>100 mm
Up Down
0
0
0
0
1
1
2
0
3
3
0
0
1
0
3
0
6
1
6
6
2
3
0
4
1
0
5
1
0
1
0
0
0
2
1
2
1
0
0
2
0
0
0
1
2
1
0
0
1
0
1
1
2
1
1
2
1
0
2
1
3
0
1
1
0
1
2
1
1
0
1
0
Dolly
Varden
>100 mm
Up Down
0
0
1
1
2
0
0
0
3
0
2
1
1
0
1
0
1
1
21
1
3
6
6
2
3
16
5
1
3
1
9
2
1
0
0
0
0
1
0
2
0
3
3
3
1
2
0
2
0
1
1
1
1
1
0
7
0
9
2
5
0
1
0
5
1
1
0
2
0
1
1
152
2008 Chuit River Fisheries Monitoring Report – Final Report
Appendix H- Continued. Salmon Trout 2002.
Chinook
salmon1
Date
Up Down
0
0
11-Sep
12-Sep
13-Sep
16-Sep
17-Sep
18-Sep
Total
1
2
0
0
0
0
0
86
0
0
0
0
0
31
Chum
salmon
Up Down
0
0
0
0
0
0
1
1
Sockeye
salmon
Up Down
0
0
0
0
0
0
0
0
0
0
0
0
0
3
0
0
0
0
0
0
Pink
salmon
Up Down
0
0
Rainbow
trout2
>100 mm
Up Down
0
1
Dolly
Varden
>100 mm
Up Down
0
0
0
0
0
0
0
109
1
2
1
0
0
94
0
0
0
0
0
110
0
0
0
0
0
51
0
0
2
0
0
77
0
0
0
1
0
42
Jack and large Chinook salmon were combined. The direction of one Chinook salmon could not be determined.
A single rainbow trout went an indeterminate direction.
LGL Alaska Research Associates, Inc.
153
2008 Chuit River Fisheries Monitoring Report – Final Report
Appendix I. Actual (unexpanded) numbers of fish passing through the video chute, by
direction, at the weir at Stream 2003 in the Chuit River drainage, June through
September, 2008. Movement was estimated by a combination of complete hour counts
and 15 minute subsample counts.
Chinook
Dolly Varden
Sockeye
trout >100
1
salmon
salmon
Pink salmon
mm
>100 mm2
Date
Up Down
Up Down
Up Down
Up Down
Up Down
30-Jun
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
0
0
0
2-Jul
3-Jul
0
0
0
0
0
0
0
1
0
0
4-Jul
0
0
0
0
0
0
1
0
0
0
5-Jul
0
0
0
0
0
0
0
1
0
0
6-Jul
0
0
0
0
0
0
1
1
0
0
8-Jul
0
0
0
0
0
0
0
1
0
0
9-Jul
0
0
0
0
0
0
2
1
0
0
10-Jul
0
0
0
0
0
0
1
0
0
0
12-Jul
0
0
0
0
0
0
1
0
0
0
13-Jul
0
0
0
0
0
0
0
2
0
0
14-Jul
0
0
0
0
0
0
1
0
0
0
17-Jul
4
2
0
0
0
0
0
1
0
0
18-Jul
2
1
0
0
0
0
1
0
0
0
19-Jul
2
2
0
0
0
0
0
0
0
0
20-Jul
4
3
0
0
0
0
0
0
0
0
21-Jul
0
1
0
0
0
0
0
0
0
0
22-Jul
1
1
0
0
0
0
1
0
0
0
23-Jul
1
0
0
0
0
0
1
2
1
0
24-Jul
1
1
0
0
0
0
0
0
0
0
25-Jul
2
1
0
0
0
0
1
0
0
0
26-Jul
0
0
0
0
1
1
2
0
0
1
27-Jul
6
0
0
0
0
0
0
0
0
0
28-Jul
8
4
0
0
2
1
0
0
0
1
29-Jul
8
7
0
0
1
1
3
0
3
0
30-Jul
3
1
0
0
0
0
2
6
1
2
31-Jul
5
4
0
0
0
0
4
4
3
1
1-Aug
6
5
0
0
0
0
1
6
4
0
2-Aug
5
3
0
0
0
0
0
0
34
17
3-Aug
0
0
0
0
0
0
1
0
18
19
4-Aug
0
0
0
0
0
0
1
1
9
4
5-Aug
0
0
0
0
0
0
3
1
1
2
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2008 Chuit River Fisheries Monitoring Report – Final Report
Appendix I- Continued. Salmon Trout 2003.
Chinook
Sockeye
salmon1
salmon
Pink salmon
Date
Up Down
Up Down
Up Down
6-Aug
3
2
0
0
0
0
7-Aug
2
0
0
0
0
0
8-Aug
8
7
0
0
0
0
9-Aug
1
1
0
0
0
0
10-Aug
0
1
0
0
0
0
11-Aug
0
2
0
0
0
0
12-Aug
0
0
0
0
0
0
13-Aug
0
1
0
0
0
0
14-Aug
0
0
0
0
0
0
15-Aug
2
0
0
0
0
0
16-Aug
0
0
0
0
0
0
19-Aug
0
0
0
0
0
0
20-Aug
0
0
0
0
0
0
21-Aug
0
0
0
0
0
0
22-Aug
0
0
0
0
0
0
23-Aug
0
0
0
0
0
0
24-Aug
0
0
0
0
0
0
25-Aug
0
0
0
0
0
0
26-Aug
0
0
0
0
0
0
27-Aug
0
0
0
0
0
0
29-Aug
0
0
0
0
0
0
30-Aug
0
0
0
0
0
0
31-Aug
0
0
0
0
0
0
1-Sep
0
0
0
0
0
0
2-Sep
0
0
0
0
0
0
3-Sep
0
0
0
0
0
0
4-Sep
0
0
2
0
0
0
5-Sep
0
0
0
0
0
0
6-Sep
0
0
1
0
0
0
7-Sep
0
0
2
0
0
0
11-Sep
0
0
0
0
0
0
12-Sep
0
0
0
0
0
0
13-Sep
0
0
0
0
0
0
16-Sep
0
0
1
0
0
0
18-Sep
0
0
0
0
0
0
LGL Alaska Research Associates, Inc.
Dolly Varden
trout >100
mm
>100 mm2
Up Down
Up Down
3
2
28
6
4
3
6
2
5
3
9
4
5
8
12
3
5
5
1
2
0
0
2
1
0
0
0
1
0
0
2
3
3
3
1
1
0
0
2
2
0
1
0
0
1
1
1
0
1
2
1
0
1
2
0
0
1
0
0
0
0
1
0
0
0
0
1
3
0
3
1
0
1
3
1
0
0
1
1
0
0
1
0
0
0
2
0
1
1
3
1
0
0
2
0
0
0
0
3
1
0
0
1
1
0
0
2
1
0
0
1
0
0
0
0
1
0
0
1
0
1
1
0
0
0
0
1
0
0
2
0
0
0
0
3
0
0
0
2
0
155
2008 Chuit River Fisheries Monitoring Report – Final Report
Appendix I- Continued. Salmon Trout 2003.
Chinook
Sockeye
1
salmon
salmon
Pink salmon
Date
Up Down
Up Down
Up Down
19-Sep
0
0
0
0
0
0
21-Sep
0
0
0
0
0
0
23-Sep
0
0
0
0
0
0
24-Sep
0
0
0
0
0
0
25-Sep
0
0
0
0
0
0
26-Sep
0
0
0
0
0
0
27-Sep
0
0
0
0
0
0
28-Sep
0
0
0
0
0
0
29-Sep
0
0
0
0
0
0
30-Sep
0
0
0
0
0
0
Total
74
50
6
0
4
3
1
2
Dolly Varden
Rainbow
trout >100
>100 mm2
Up Down
Up Down
0
0
2
1
0
0
1
0
0
0
1
1
0
0
1
0
1
0
3
0
0
1
0
2
0
0
3
2
0
0
1
0
0
1
3
0
0
0
1
2
63
79
174
88
Jack and large Chinook salmon were combined. The direction of one Chinook salmon could not be deternined.
The direction of one Dolly Varden could not be determined.
LGL Alaska Research Associates, Inc.
156
2008 Chuit River Fisheries Monitoring Report – Final Report
Appendix J. Actual (unexpanded) numbers of fish passing through the video chute, by
direction, at the weir at Stream 2004 in the Chuit River drainage, June through
September, 2008. Movement was estimated by a combination of complete hour counts
and 15 minute subsample counts.
Dolly Varden
Rainbow trout
1
2
Chinook salmon
Sockeye salmon
>100 mm3
>100 mm
Date
Up Down
Up Down
Up Down
Up Down
29-Jun
0
0
0
0
1
0
0
0
30-Jun
0
0
0
0
1
1
0
0
1-Jul
0
0
0
0
1
0
0
0
2-Jul
0
0
0
0
3
1
0
0
3-Jul
0
0
0
0
0
1
0
0
4-Jul
0
0
0
0
1
2
0
0
5-Jul
0
0
0
0
1
2
0
0
6-Jul
0
0
0
0
4
2
0
0
7-Jul
0
0
0
0
3
3
0
0
8-Jul
0
0
0
0
1
1
0
0
9-Jul
0
0
0
0
1
0
0
0
10-Jul
0
0
0
0
1
0
0
0
12-Jul
0
0
0
0
1
1
0
0
13-Jul
0
0
0
0
4
4
0
0
14-Jul
0
0
0
0
3
1
0
0
15-Jul
0
0
0
0
2
1
0
0
16-Jul
0
0
0
0
3
0
0
0
17-Jul
0
0
0
0
5
1
0
0
18-Jul
0
0
0
0
3
4
1
1
19-Jul
1
0
0
0
2
6
1
0
20-Jul
0
0
0
0
7
12
0
0
21-Jul
0
0
0
0
0
7
0
0
22-Jul
0
0
0
0
1
0
0
0
23-Jul
0
0
0
0
0
0
1
0
24-Jul
3
0
0
0
0
0
0
0
25-Jul
0
2
0
0
0
2
0
0
27-Jul
2
0
0
0
0
0
2
2
28-Jul
0
0
0
0
1
1
2
2
29-Jul
0
1
0
0
0
0
0
0
30-Jul
0
0
0
0
2
2
0
0
31-Jul
0
0
0
0
0
1
2
0
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2008 Chuit River Fisheries Monitoring Report – Final Report
Appendix J- Continued. Salmon Trout 2004.
1
Date
1-Aug
2-Aug
3-Aug
4-Aug
5-Aug
6-Aug
7-Aug
8-Aug
9-Aug
10-Aug
11-Aug
12-Aug
13-Aug
14-Aug
15-Aug
16-Aug
17-Aug
18-Aug
19-Aug
20-Aug
21-Aug
22-Aug
23-Aug
24-Aug
25-Aug
26-Aug
27-Aug
29-Aug
30-Aug
31-Aug
2-Sep
3-Sep
4-Sep
5-Sep
Chinook salmon
Up Down
1
0
2
1
3
2
8
3
5
1
0
0
3
0
1
1
0
1
2
2
0
1
2
1
3
1
0
0
3
0
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
LGL Alaska Research Associates, Inc.
Sockeye salmon
Up Down
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
3
0
0
3
6
2
0
0
2
0
0
Rainbow trout
>100 mm2
Up Down
2
2
4
0
2
2
4
0
2
2
1
0
2
0
0
1
0
1
0
1
1
0
1
0
1
2
1
2
4
2
1
1
1
0
2
0
2
1
1
1
2
1
0
0
2
0
1
1
1
0
0
1
2
2
3
3
0
0
0
1
1
1
2
1
0
0
2
2
Dolly Varden
>100 mm3
Up Down
3
1
4
6
3
1
0
0
4
1
0
2
5
0
0
0
6
0
2
1
0
0
1
1
1
0
0
1
1
0
2
0
3
1
0
0
0
1
2
0
0
0
1
1
0
0
0
1
1
0
0
0
1
3
0
0
2
0
1
1
2
1
7
2
4
4
6
7
158
2008 Chuit River Fisheries Monitoring Report – Final Report
Appendix J- Continued. Salmon Trout 2004.
1
Date
6-Sep
7-Sep
8-Sep
9-Sep
10-Sep
11-Sep
12-Sep
15-Sep
16-Sep
18-Sep
19-Sep
22-Sep
23-Sep
24-Sep
25-Sep
26-Sep
28-Sep
29-Sep
Total
1
2
3
Chinook salmon
Up Down
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
39
19
Sockeye salmon
Up Down
0
0
0
0
1
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
0
11
12
Rainbow trout
>100 mm2
Up Down
4
2
0
0
1
1
5
2
4
4
0
0
4
2
0
0
1
0
0
0
0
0
1
0
0
0
1
0
0
0
0
0
0
1
0
2
121
101
Dolly Varden
>100 mm3
Up Down
9
4
5
1
6
2
0
0
0
0
2
1
0
0
1
0
6
0
1
0
1
0
0
0
0
2
0
0
0
0
0
1
1
2
0
1
103
55
Large and jack Chinook made up all counts.
The direction of three rainbow trout could not be determined.
The direction of one Dolly Varden could not be determined.
LGL Alaska Research Associates, Inc.
159