Part 4 - Manitoba Hydro

Transcription

Scale: 1:1,180,114
Created By: cparker - B Size Landscape BTB - MAR 2015
Hudson Bay
Churchill
HUDSON
BAY
Thompson
Indian
Lake
Fidler
Lake
RCEA
Area 2
e
Riv
Crying
Lake
Fox Lake (Bird)
Clark
Lake
Tataskweyak Cree Nation
Tataskweyak (Split Lake)
Gull Lake
280
File Location: J:\MYP\MH_RCEA\Fish_Quality\PHASE_2\Mxd\Mercury\20151028_RCEA_PhaseII_AE_FQ_EE_WaterbodiesWithInformationOnMercuryInFishRCEAArea2_cp.mxd
Split Lake
Kelsey
G.S.
Aike
n
Kettle
G.S.
Stephens
Lake
Keeyask
G.S.
Butnau
Lake
Assean
Lake
York Factory
First Nation
n
ls o
Ne
Fox Lake
Cree Nation
r
r
Hayes
Rive
Conawapa
G.S.
Limestone
G.S.
290
Long Spruce G.S.
Gillam Fox Lake Cree Nation
A Kwis Ki Mahka Reserve
Moose Nose
Lake
R.
War Lake First Nation
Ilford (NAC)
York Landing
(Kawechiwasik)
War Lake
Shamattawa
First Nation
DATA SOURCE:
Government of Canada, Province of Manitoba, North/South Consultants and
Manitoba Hydro.
CREATED BY:
North/South Consultants
COORDINATE SYSTEM:
Regional Cumulative Effects
Assessment
NAD 1983 UTM Zone 15N
0
0
10
20 Kilometres
10
20 Miles
DATE CREATED:
REVISION DATE:
27-AUG-15
08-DEC-15
VERSION NO:
QA/QC:
Legend
Fish Mercury Information
Generating Station (Existing)
Highway
Focal Waterbody
Generating Station (Under Construction)
First Nation Reserve
RCEA Region of Interest
Generating Station (Potential)
Waterbodies with Information
on Mercury in Fish
RCEA Area 2
1.0
Map 5.5.3-1
REGIONAL CUMULATIVE EFFECTS ASSESSMENT – PHASE II
WATER – MERCURY IN FISH
Seven focal waterbodies were selected for detailed presentation in the following discussion. These lakes
and rivers were chosen because they experienced flooding (e.g., Stephens Lake, Long Spruce forebay;
Limestone forebay) or other hydrological changes related to hydroelectric development (e.g., Nelson
River downstream of Limestone), and where possible had fish mercury data with relatively good sample
sizes and collection frequency to allow conclusions on the evolution of fish mercury concentrations over
an extended time period (e.g., Split Lake). Assean Lake and the Hayes River were included as focal
waterbodies because they are off-system and serve as CAMP reference waterbodies. The Aiken River
was chosen as a focal waterbody because it is the only river in Area 2 (and in the entire ROI) for which
fish mercury data were systematically collected from two separate sites, allowing for the analysis of intersite differences in fish mercury concentrations for a fluvial system. More limited site-specific data were
also available for the lower Nelson River.
5.5.3.3
Changes in Mercury Concentrations over Time
This section provides a detailed description of the time series of fish mercury observed for each focal
waterbody. Subsequent sections will compare mercury concentrations to standards and guidelines and
discuss the evolution of fish mercury concentrations in Area 2 with respect to hydroelectric development.
5.5.3.3.1
Split Lake
Split Lake has one of the longest and the most complete record of fish mercury concentrations in the
entire ROI. First commercial data are available for 1969 and over the following 44 years mercury
concentrations have been measured for at least one of the three focal species in 29 years
(Figure 5.5.3-1). Mean mercury concentrations in Northern Pike and Walleye from Split Lake have
fluctuated greatly over the 20-year period from 1970–1990 (Figure 5.5.3-1) without showing any trends
that could be attributed to the operation of either LWR (which affected flows into Split Lake by mid-1976)
or CRD (which would have reduced flows into Split Lake from May 1974 to November 1975 and
substantially increased flows by mid-1976). Maximum mean concentrations for survey samples of at least
10 fish were observed in 1982 for both pike (0.52 ppm) and Walleye (0.66 ppm). Starting in 1992,
mercury concentrations began to decrease almost continuously and by 2005 reached all-time minimums
of 0.18 ppm in pike and 0.12 ppm in Walleye. Lake Whitefish, for which non-commercial data are only
available since 1983, showed a much smaller range in mercury concentrations than the two piscivorous
species, but also decreased significantly from a maximum concentration of 0.11 ppm in 1986 to 0.03 ppm
in 2005 (Figure 5.5.3-1). Since then, mercury levels have increased significantly in all three focal fish
species and currently (2013) are 2–3 times higher than the 2005 minima.
DECEMBER 2015
5.5-34
Start of flow changes due to
Muscle mercury (ppm)
1.2
LWR
Split Lake
CRD
Pike
Walleye
Whitefish
1.0
0.8
n=7
*
n=5
*
n=5
*
*
0.6
n=5
*
*
*
*
*
0.4
*
n=5
*
*
*
n=5
0.2
*
0.0
70
19
75
19
80
19
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
Means without CLs prior to 1980 are from commercial samples. An asterisk indicates that the relationship between fish length and
mercury concentration was not significant and the arithmetic mean was use; n represents sample size. The stippled line indicates
the 0.5 ppm Health Canada standard for retail fish.
Figure 5.5.3-1:
Mean (95% Confidence Limits [CL]) Length Standardized Muscle Mercury
Concentrations of Northern Pike, Walleye, and Lake Whitefish From Split Lake
for 1969–2013
Fish mercury data for Split Lake also include several other species with records that span multiple years
with means based on larger sample sizes than for most other lakes. These results illustrate that mercury
concentrations of the mainly planktivorous Cisco (Coregonus artedi) were close to 0.1 ppm between 1983
and 1998 (Figure 5.5.3-2), and thus similar to those of the benthivorous Lake Whitefish. Concentrations in
two common catostomids, White Sucker and Longnose Sucker, which diet is best described as
benthivorous detritivors (Ahlgreen 1990a,b) were generally slightly below and slightly above 0.2 ppm,
respectively, from 1983–1986 (Figure 5.5.3-2). These mercury levels are slightly (for White Sucker) or
substantially (for Longnose Sucker) higher than concentrations in Cisco and whitefish from Split Lake and
from any other waterbody in Area 2 for a comparable time-period. Concentrations in Longnose Sucker
were similar compared to their conspecifics from the Nelson River downstream of the Limestone GS in
1992 and significantly lower than Longnose Sucker from Threepoint Lake in 1985 and 1992
(Figure 5.5.4-6). White Sucker had higher concentrations than their conspecifics from the Aiken River in
2002 and 2003 (see discussion in Section 5.5.3.3.6), but concentrations were often significantly lower
compared to White Sucker from Threepoint Lake from 1981–1985 (Figure 5.5.4-6). Disregarding the
DECEMBER 2015
5.5-35
small sample of fish for 1976, Sauger from Split Lake had mercury concentrations of 0.44–0.67 ppm in
years 1982 to 1989 (Figure 5.5.3-2). Although means were highly variable (despite sample sizes of
mainly 50 or more fish), these results are similar than those for Walleye from Split Lake in comparable
years and confirm that mercury concentrations in piscivorous species are elevated relative to species of
lower trophic levels.
1.2
LWR
Split Lake
CRD
White Sucker
Longnose Sucker
Cisco
Sauger
1.0
0.8
n=7
0.6
0.4
*
n=3
*
n=6
*
0.2
*
0.0
75
19
80
19
85
19
90
19
95
19
00
20
Year
An asterisk indicates that the relationship between fish length and mercury concentration was not significant and the arithmetic
mean was use; n represents sample size. The stippled line indicates the 0.5 ppm Health Canada standard for retail fish.
Figure 5.5.3-2:
Mean (95% Confidence Limits) Length Standardized Muscle Mercury
Concentrations of White Sucker, Longnose Sucker, Cisco, and Sauger From
Split Lake for 1976–1998
5.5.3.3.2
Stephens Lake
Stephens Lake/reservoir was flooded by approximately 226% of its original area just prior to the in-service
data of the first turbine unit at Kettle GS in December of 1970. Mercury concentrations in Lake Whitefish
(0.19 ppm), Northern Pike (1.05 ppm), and Walleye (1.89 ppm) from Stephens Lake were highest when
first sampled (second sample for whitefish) more than 10 years after impoundment in 1970
(Figure 5.5.3-3). These maxima represented an increase factor (IF; the ratio of the maximum mercury
concentration observed post-flooding to the pre-flooding concentration) of 6.9 for Walleye, 3.5 for pike,
and 3.1 for whitefish (Table 5.5.4-3 in Area 3). However, since mercury concentrations of the above
DECEMBER 2015
5.5-36
species typically peak within 3 to 8 years of flooding (Bodaly et al. 2007), maximum mercury
concentrations (and the IFs) in fish from Stephens Lake were likely substantially higher than those first
recorded in the early 1980s. Similar to all other lakes in the ROI that experienced substantial flooding,
mercury concentrations in pike and Walleye from Stephens Lake decreased almost continuously after the
first measurements, reaching 0.18 ppm in pike and 0.20 ppm in Walleye by 2005. Whitefish showed a
similar, although less consistent declining trend; by 2005 mercury concentrations (0.03 ppm) were about
15% of those initially recorded. Since then, mercury levels have increased significantly in all three focal
fish species and currently (2012) are approximately 30–80% higher than the 2005 minima
(Figure 5.5.3-3).
2.0
*
2.33
n=5
Stephens Lake
Pike
Walleye
Whitefish
1.6
Year of
impoundment
n=9
1.2
0.8
n=4
0.4
n=5
*
*
n=6
0.0
70 80
19 19
85
19
90
19
95
19
00
20
*
05
20
n=7
10
20
n=5
15
20
Year
mean was used; a number denotes an upper CL not shown as a bar; n represents sample size. The stippled line indicates the
0.5 ppm Health Canada standard for retail fish.
Figure 5.5.3-3:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From Stephens
Lake for 1981–2013
5.5.3.3.3
Long Spruce Forebay
The Long Spruce forebay was created in 1977 by flooding the Nelson River valley increasing the water
surface area by approximately 92%.
DECEMBER 2015
5.5-37
Mercury concentrations in Lake Whitefish (0.18 ppm), Northern Pike (0.70 ppm), and Walleye (0.64 ppm)
from the Long Spruce forebay were highest when first sampled (second sample for Walleye) eight years
after impoundment in 1977 (Figure 5.5.3-4). The maxima represented IFs of 2.8 for whitefish, and 2.3 for
pike and Walleye (Table 5.5.4-3 in Area 3). However mercury concentrations of the above species
typically peak within 3 to 8 years of flooding (Bodaly et al. 2007), and it can be assumed that maximum
mercury concentrations (and their IFs) in fish from the Long Spruce forebay were somewhat higher than
those first recorded in the mid-1980s.
1.0
Long Spruce Forebay
Year of
impoundment
Pike
Walleye
Whitefish
0.8
0.6
0.4
0.2
0.0
80 85
19 19
90
19
95
19
00
20
05
20
Year
The stippled line indicates the 0.5 ppm Health Canada standard for retail fish.
Figure 5.5.3-4:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From the Long
Spruce Forebay for 1985–2003
As is typical for newly created reservoirs in the ROI (and elsewhere), mercury concentrations in all three
focal species from the Long Spruce forebay decreased almost continuously until 2003 after reaching
(assumed) maxima in the early 1980s. Fish mercury monitoring at the Long Spruce forebay was
discontinued after 2003 and it is unknown if concentrations were still declining at that time. Considering
that most other on-system waterbodies in Area 2 (and in the entire ROI) with a suitable record of fish
mercury data show a further decline in mercury concentrations of pike and Walleye between samples
DECEMBER 2015
5.5-38
taken in the early 2000s and 2005, it can be expected that concentrations in at least the two predatory
species from the Long Spruce forebay had not yet reached a minimum by 2003.
5.5.3.3.4
Limestone Forebay
The Limestone forebay was created by flooding the Nelson River valley in 19909, increasing the water
surface area by just over 8%.
Fish mercury concentrations increased rapidly in the Limestone forebay after impoundment and reached
maximum levels within two years after flooding in Lake Whitefish (0.14 ppm) and within five years in
Northern Pike (0.45 ppm), and Walleye (0.64 ppm; Figure 5.5.3-5). The maxima represented IFs of 2.3 for
Walleye, 1.7 for whitefish, and 1.4 for pike (Table 5.5.4-3 in Area 3). Except for a transient increase in
2003, mercury concentrations in pike and Walleye have decreased continuously and significantly since
1994; reaching minima of 0.18 ppm in Walleye and 0.19 ppm in pike in 2005 (the same concentration was
also recorded in 2001). The return times to the lowest post-flood concentrations were eight years for pike
and 13 years for Walleye (Table 5.5.4-3) Mean standard concentrations in whitefish have also steadily
decreased from 1991 to 2001, although not significantly (Figure 5.5.3-5). The high arithmetic mean of
0.14 ppm recorded in 2005 is for a relatively small sample of 10 very large (mean fork length = 494 mm)
individuals. Only one and two whitefish were available for mercury analysis in 2010 and 2013,
respectively and results are not shown in Figure 5.5.3-5).
Mercury concentrations in pike and Walleye from the Limestone forebay have increased significantly from
2005 to 2010. Concentrations have remained relatively high in 2013, although the standard mean for pike
was statistically similar to that recorded in 2005.
DECEMBER 2015
5.5-39
1.0
Start of
flooding
Limestone Forebay
Pike
Walleye
Whitefish
0.8
0.6
0.4
*
* n=5
0.2
*
0.0
90
19
95
19
00
20
05
20
10
20
15
20
Year
mean was used; n represents sample size. The mean of 0.62 ppm for three Walleye in 1989 is not shown. The stippled line
indicates the 0.5 ppm Health Canada standard for retail fish.
Figure 5.5.3-5:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From the
Limestone Forebay for 1989-2013
5.5.3.3.5
Lower Nelson River
The Nelson River between the Limestone GS and the estuary at Port Nelson extends over approximately
111 km. Fish mercury data from this section of the lower Nelson River exist from the freshwater portion of
the estuary near Port Nelson for the years 1975-1997 (commercial data only for 1975–1977) and from
several reaches of the river mainstem starting just downstream of the Limestone GS to Seal Island,
approximately 15 km upstream of Port Nelson (Map 5.5.3-1). As outlined in Section 5.5.3.2, conditions for
mercury availability and bioaccumulation may vary over the length of the Nelson River mainstem,
potentially resulting in differences in fish mercury concentrations among sites. To test this hypothesis,
data collected for several species from six different river reaches during the same sampling year were
compared for between-site differences in mercury concentrations. In all cases, the frequently observed
differences in arithmetic means between sites were associated with differences in mean fish length, and
standard means were statistically similar (for an example see Figure 5.5.3-6). Therefore, available data
for the three focal species from all river reaches (including the estuary) were combined to evaluate
DECEMBER 2015
5.5-40
temporal trends in fish mercury for the lower Nelson River below the Limestone GS between the mid1970s and 2013.
Mercury (ppm)
0.2
Arithmetic mean
a
a,b
0.1
b,c
b,c
c
0.0
400
Length (mm)
a
Fork length
a,b
300
b,c
b,c
c
200
100
0
b
Mercury (ppm)
0.2
Standard mean
0.1
n.s.
n.s.
0.0
1
2
3
4
5
6
Reach
Different letters indicate significant differences between means. Standard means were not calculated if the relationship between
mercury concentration and fish length was not significant (n.s.).
Figure 5.5.3-6:
Mean Arithmetic Standard Error and Standardized (Upper 95% Confidence
Limit) Mercury Concentration, and Mean Standard Error Fork Length of Lake
Whitefish Collected From Several Reaches of the Nelson River Mainstem in
1992
DECEMBER 2015
5.5-41
Mercury concentrations of pike (0.78–1.17 ppm) and Walleye (0.67–0.88 ppm) were highest for the
commercial samples collected from 1974–1976 and the arithmetic mean for 15 very large
(mean fork length = 733 mm) pike in 1982 (Figure 5.5.3-7). Likely a partial result of the often small sample
sizes, particularly for walleye, concentrations in both predatory species fluctuated substantially in the
1980s and 1990s, but generally declined. Both pike and Walleye had a standard mean of 0.13 ppm in
2004. Thereafter, concentrations have increased significantly in both species and are currently (2013)
more than twice as high as the 2004 minimum. Standard means for Lake Whitefish from 1986–2013
sometimes differed significantly between years, but not in a manner indicative of a time trend. Similar
minimum concentrations of 0.07 ppm were recorded in 2004 and 2011. The arithmetic mean of 0.19 ppm
for 2013 is for 10 very large (mean fork length = 429 mm) fish.
1.4
Kettle 1970
Long
LWR CRD Spruce
Limestone
Pike
Walleye
Whitefish
1.2
*
Nelson River
1.0
0.8
*
* n=5
n=6
*
0.6
*
n=6
*n=6
n=5
n=5
*
*
n=5
*
0.4
*
n=6
0.2
*
*
0.0
75
19
80
19
n=3
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
Means without CL prior to 1980 are from commercial samples. An asterisk indicates that the relationship between fish length and
mercury concentration was not significant and the arithmetic mean was used. A number denotes an upper CL not shown as a bar; n
represents sample size. The stippled line indicates the 0.5 ppm Health Canada standard for retail fish.
Figure 5.5.3-7:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From the Lower
Nelson River Downstream of the Limestone Generating Station for 1975–2013
DECEMBER 2015
5.5-42
5.5.3.3.6
Aiken River
The Aiken River is a tributary to Split Lake, entering the lake from the southeast (Map 5.5.3-1). The two
sampling sites on the river upstream of York Landing and a further 25 km upstream near Ilford did not
experience any flooding.
Walleye and Northern Pike from the Aiken River at Ilford have been analyzed for mercury since 1978.
However, until 2002 sample sizes have always been small (3–8 fish) for both species and only in two
cases has the relationship between fish length and mercury concentration been significant during this
time period. Except for the relatively small samples of pike and Walleye from the Aiken River at York
Landing, information on fish mercury concentrations from this site only exist since 2003. Mercury data for
Lake Whitefish are not available for the Aiken River, but some information exists for White Sucker.
Mercury concentrations in pike and Walleye from the Aiken River at Ilford have fluctuated substantially
prior to 2002, likely a result of the generally small sample sizes. Concentrations in pike ranged from
0.20 ppm to 0.40 ppm whereas Walleye always had lower arithmetic mean concentrations than pike
(sometimes significantly for the same year), ranging from 0.08 ppm to 0.24 ppm. Since 2002 standard
means of Walleye have consistently and significantly increased and are currently (2012) approximately
60% higher (Figure 5.5.3-8). In contrast, standard means of pike have fluctuated without a significant
change.
Northern Pike and Walleye from the Aiken River at York Landing had substantially higher concentrations
(significantly for Walleye) than their conspecifics from the river at Ilford when first sampled in 1982
(Figure 5.5.3-8). However, when next analyzed in 2003 with larger fish sample sizes, standard means of
each species at the two locations were similar and continued to be so until last sampled in 2012. Both
pike (0.26 ppm) and Walleye (0.19 ppm) from the river at York Landing reached minimum concentrations
in 2006 after which they significantly increased in 2009 and 2012 (Figure 5.5.3-8). Although having been
sampled mostly one year apart since 2002, pike and Walleye from the Aiken River collected during the
spawning season generally had very similar mercury concentrations to their conspecifics sampled several
months later from several locations within Split Lake.
Fish mercury information for the Aiken River also exists for some larger samples of White Sucker in 2002
(from Ilford only) and 2003. All three samples have standard means of 0.09 ppm and are lower
(although not significantly) than the standard means (0.13–0.17 ppm) of their conspecifics from Split Lake
in 1983, 1984, and 1986 (see Section 5.5.3.3-1) As it can be assumed that White Sucker captured on the
spawning grounds in the Aiken River have mainly been feeding and accumulating mercury within Split
Lake, these results indicate that other species, and those of lower trophic levels, show a similar pattern of
decline in mercury concentrations for the 1980–2005 period as has been repeatedly shown for Walleye
and pike.
DECEMBER 2015
5.5-43
1.0
Aiken River
Pike, YL
Pike, IF
Walleye, YL
Walleye, IF
0.8
*
n=7
0.6
0.4
n=5
*
n=5
n=5
n=6
n=6
0.2
n=6
*
n=7
*
*
*
*
n=5
*
n=5
n=6
n=5
n=3
*
* *
*
*
*
*
*
*
n=5
n=5
*
n=6
n=6
0.0
75
19
80
19
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
mean was used; n represents sample size. The stippled line indicates the 0.5 ppm Health Canada standard.
Figure 5.5.3-8:
Concentrations of Northern Pike and Walleye From the Aiken River at York
Landing and Ilford for Years 1978–2012
5.5.3.3.7
Assean Lake
Except for one commercial sample and two survey samples with small (n < 10) fish numbers, standard
concentrations of all three focal species from Assean Lake, the off-system reference lake for the lower
Nelson River Region of CAMP (CAMP 2014), were relatively stable and without an obvious time trend
over the period of record 1981–2013. Concentrations ranged from 0.19–0.25 ppm in pike, 0.18–0.32 ppm
in Walleye, and 0.04–0.06 ppm in whitefish (Figure 5.5.3-9). While no statistical difference existed
between any of the yearly concentrations for whitefish, the standard mean for pike in 2010 was just
significantly higher than the standard mean for 2001, and the standard mean for Walleye in 2013 was
significantly higher than the means for 1985, 2001, 2002, and 2010.
When comparing the time-lines of mercury concentrations of fish from Assean Lake with those of onsystem lakes in order to evaluate potential system effects in Area 2 (or beyond), it must be noted that the
temporal resolution of fish mercury data is lower than for most on-system lakes. This is important because
the absence of data for Assean Lake during times of dynamic change in fish mercury of on-system lakes
limits our interpretation of the observed pattern. This is well exemplified by the time period 2001–2013, for
DECEMBER 2015
5.5-44
which no fish mercury data exist for Assean Lake between 2003 and 2009, while the results from several
on-system waterbodies indicate that mercury concentrations in at least pike and Walleye reached a
minimum in or within one year of 2005 and since have increased significantly (see Sections 5.5.3.3.1,
5.5.3.3.2, and 5.5.3.3.4).
1.0
LWR
Assean Lake
CRD
Pike
0.8
Walleye
Whitefish
0.6
n=5
*
0.4
n=6
*
0.2
n=6
n=9
*
*
0.0
70
19
75
19
80
19
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
mercury concentration was not significant and the arithmetic mean was used; n represents sample size. The stippled line indicates
the 0.5 ppm Health Canada standard for retail fish.
Figure 5.5.3-9:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From Assean
Lake for 1978–2013
5.5.3.3.8
Hayes River
Except for three commercial samples (mean of 0.02 ppm) for Arctic Char (Salvelinus alpinus) collected in
1970 (Derksen 1978a), fish mercury data from the Hayes River are available only since 2006. In 2006
and 2009 samples were taken at a location closer to the river mouth, whereas the more recent data come
from the CAMP sampling site further upstream (Map 5.3.3-1). For the current analysis, data from both
recent sampling locations have been combined. Standard means of Walleye have been statistically
similar for 2006 and 2010, ranging from 0.35 ppm to 0.46 ppm, but were significantly lower (0.29 ppm) in
2013 compared to 2010 (Figure 5.5.3-10). Mercury concentrations in pike showed a similar temporal
DECEMBER 2015
5.5-45
pattern as Walleye with standard means at or just below 0.2 ppm. However, because of high confidence
limits due to small sample sizes in 2010 and 2013, no significant differences existed between mean
concentrations in pike. Arithmetic means indicated that mercury levels were consistently and often
significantly lower in pike than in Walleye.
Hayes River
Pike
Walleye
Whitefish
0.6
0.4
*
n=3
0.2
n=8
n=9
*
n=5
0.0
00
20
05
20
10
20
15
20
Year
mean was used. The stippled line indicates the 0.5 ppm Health Canada standard for retail fish.
Figure 5.5.3-10:
Concentrations of Northern Pike Walleye, and Lake Whitefish From the Hayes
River for 2006–2013
Mercury concentrations in whitefish ranged from 0.07 to 0.09 ppm over the three available sampling years
between 2006 and 2011 (Figure 5.5.3-10).
5.5.3.4
Cumulative Effects of Hydroelectric Development on Fish
Mercury Concentrations in Area 2
5.5.3.4.1
Comparison to Benchmarks
With the exception of Northern Pike from the Limestone forebay, mercury concentrations in piscivorous
fish species from all Area 2 waterbodies that were flooded in the course of the construction of a
DECEMBER 2015
5.5-46
hydroelectric generating station have at some point substantially exceeded the Health Canada standard
of 0.5 ppm for the commercial sale of fish (e.g., Figures 5.5.3-4 to 5.5.3-6). Of the three generating
stations in Area 2, the Limestone GS has created the least amount of areal flooding, and pike and
Walleye from the Limestone forebay have experienced the smallest increase in mercury concentration,
with the maximum for pike remaining just below and that of Walleye just above the standard. (For a
detailed discussion of the relationship between the amount of flooding and fish mercury concentrations,
see Section 5.5.4.4.3)
In addition to the fish in newly created forebays, pike, Walleye, and Sauger from other on-system
waterbodies in Area 2 have routinely exceeded mean concentrations of 0.5 ppm during the first
2 decades of fish mercury monitoring in Manitoba (1969–1990). With few notable exceptions, such as
Walleye (Figure 5.5.3-1) and Sauger (Figure 5.5.3-2) from Split Lake, the vast majority of these
exceedances, which have generally been less severe than for the reservoirs, have been for commercial
samples and small survey samples of larger fish (relative to the standard length of the species; Figures
5.5.3-2 and 5.5.3-8). The high concentrations observed in large (commercially caught) Walleye and pike
from Split Lake when first sampled in 1970 did result in the partial (whitefish were still accepted for
marketing) closure of the commercial fishery of the lake from July 1970–1976 (Derksen 1978b). These
decisions were made at a time when not much was known about mercury concentrations in Manitoba fish
and, as can be interpreted from the course of events in 1969–1970 described in Bligh (1971), the
Province likely was under substantial public pressure to protect consumers in light of the recent reports
from highly contaminated fish in the Saskatchewan River (see Section 5.5.1.2).
The mercury concentrations of 0.55 ppm (pike) and 0.76 ppm (Walleye) for the commercial samples in
1970 and of 0.47–0.75 ppm for survey samples of Walleye from 1972–1974 could not have been caused
by LWR or CRD, which had not yet commenced at the time. A residual effect from the 1960 flooding of
the Kelsey forebay and several upstream Lakes (e.g., Sipiwesk) is also unlikely. This because a potential
downstream effect from the export of methylmercury in water and lower trophic level organisms into a
large waterbody such as Split Lake must have been small, particularly almost 10 years after the initial
increase in methylmercury availability from flooding. Even if some pike and Walleye which may have
reached high (2.0 ppm) mercury concentrations 3–9 years after Kelsey flooding migrated downstream
from waterbodies upstream of the generating station (no studies have been carried out to document such
movements other than for Lake Sturgeon), their numbers would not have been large enough to
measurably affect mean mercury concentrations of the (presumably) several hundred thousand adult
conspecifics in Split Lake in the early 1970s. Instead the elevated (above 0.5 ppm) mercury
concentrations of pike and Walleye from Split Lake during that time are most likely attributable to the
large fish sampled for mercury from the commercial catches and for most of the (small) survey samples.
A similar situation could occur even today. If only a few of the largest pike and Walleye from a current
CAMP sample at Split Lake (or most other waterbodies) would be selected for mercury analysis, the
likelihood of a mean arithmetic mercury concentration exceeding 0.5 ppm is very high (W. Jansen, North
South Consultants Inc.[NSC], pers. observation).
The recent (post-2005) significant increases in mercury concentrations of mainly pike and Walleye
observed for almost all on-system waterbodies in Area 2 have not resulted in concentrations that exceed
the Health Canada 0.5 ppm standard.
DECEMBER 2015
5.5-47
More limited results for other fish species in Area 2 waterbodies also indicate that mercury concentrations
mainly follow fish trophic level and size (age), and that they can exceed 0.5 ppm in piscivores but usually
remain below 0.2 ppm in species feeding primarily on invertebrates and/or detritus. Mean concentrations
in Sauger from Split Lake and the Limestone forebay, at least prior to 1994 (more recent data are not
available) have exceeded the 0.5 ppm Health Canada standard. Cisco, for which recent data are also
lacking, generally has mercury concentrations of ≤0.1 ppm and similar to Lake Whitefish. White Sucker
from Split Lake (Figure 5.5.3-2) and the Aiken River (in 2003), also had concentrations close to 0.1 ppm.
Longnose Sucker from Split Lake and the lower Nelson River had higher mercury levels than White
Sucker in the past, sometimes clearly exceeding 0.2 ppm, but recent (>1992) data are not available.
Concentrations in Burbot from the Limestone forebay were generally slightly higher than 0.2 ppm except
for one sample of four fish in 1992 which had a concentration of 0.61 ppm and exceeded the Health
Canada standard.
Together with the Churchill River in Area 4 (see Section 5.5.5.5.1), Area 2 has the most extensive
information on Lake Sturgeon mercury concentrations in the ROI. Concentrations obtained from the
Nelson and Hayes rivers indicate that individual sturgeon did not normally exceed 0.2 ppm for fork
lengths up to 100 cm, but some larger fish reached concentrations that exceed the 0.5 ppm standard for
human consumption (Table 5.5.3-1).
DECEMBER 2015
5.5-48
Table 5.5.3-1:
Arithmetic Mean (range) Mercury Concentrations, Parts-per-Million, and Fork
Length for Lake Sturgeon from Two Reaches of the Nelson River (downstream of
Limestone Generating Station to Gillam Island, and the estuary), the Hayes River,
and Split, Gull, and Stephens Lakes
Year
n
Hg, Mean
2014
2
Nelson River, downstream Limestone GS
0.190
0.15–0.23
766.5
2013
1
0.035
-
425
2011
3
0.166
0.14–0.21
693.7
654–715
2010
6
0.313
0.18–0.38
1086.7
690–1,345
2008
7
0.159
0.08–0.28
672.3
537–800
2003
7
0.185
0.13–0.34
841.4
725–1,200
4
0.11
0.09–0.13
-
-
1970
a
Hg, Range
Length, Mean
Length, Range
703–830
-
Nelson River, estuary
1982
a
5
0.220
0.10–0.60
-
-
1983
a
1
0.12
-
-
-
1982
a
1
0.12
-
-
-
1978
a
1
0.10
-
-
-
1977
a
1
0.06
-
-
-
1976
a
1
0.16
-
-
-
1975
a
1
0.06
-
-
-
1970
a
5
0.10
-
-
-
Hayes River
2013
1
0.176
-
-
720
2011
1
0.213
-
-
771
2010
1
0.194
-
-
664
2009
2
0.098
0.07–0.13
550.5
543–558
-
-
Split Lake
1970
a
1
0.014
2014
1
0.166
-
-
-
2013
1
0.052
-
-
-
2006
1
0.039
-
-
-
2004
10
0.207
0.04–0.67
1158.8
1,035–1,286
2002
3
0.166
0.10–0.21
1162.5
1,050–1,275
Gull Lake
Stephens Lake
a
2014
1
0.100
-
-
598
2012
1
0.174
-
-
802
2008
1
0.099
-
-
587
Commercial samples
DECEMBER 2015
5.5-49
5.5.3.4.2
Evolution of Fish Mercury Concentrations in Relation to
Hydroelectric Development
CHURCHILL RIVER DIVERSION AND LAKE WINNIPEG REGULATION
Lake Winnipeg Regulation affected inflows to Split Lake via the Nelson River. Inflows into the lake were
reduced during summer and fall 1973 due to the construction of cofferdams in the west channel of the
Nelson River. Two Mile Channel was completed in mid-1976, at which time flow regulation related to
LWR, impoundment of the Jenpeg forebay, and changes to inflows to Split Lake were fully implemented.
The monthly average discharge at Kelsey GS pre- and post-LWR shows that LWR increased winter flows
at Kelsey, and, on average, decreased open water flow (Water Regime, Section 4.3.2.4.3). Operation of
the Kelsey GS does not cause substantial water level changes to Split Lake. Higher flows
(approximately 7-fold increase) in the Burntwood River as a result of CRD entered Split Lake starting in
mid-1976. Post-CRD/LWR water levels have been 0.4 m higher on average than pre-CRD/LWR water
levels. Also, there was a seasonal reversal in water levels because average winter levels are typically
higher than average summer levels (see Sections 5.5.3 and 5.5.3.3.1).
The above changes in hydraulic conditions due to CRD/LWR apparently had little effect on mercury
concentrations in whitefish, pike, and Walleye from Split Lake. Any increase in concentrations that may
have occurred a few years after the initial post-CRD increase in Split Lake water levels were too small to
be detected within the large variability of mean concentrations in the 1970s and 1980s. Mercury
concentrations in pike and Walleye from Split Lake have fluctuated greatly over this period
(Figure 5.5.3-1) and the timeline of concentration changes does not correlate with any of the key
hydrological events of CRD/LWR.
RESERVOIRS AND OTHER ON-SYTEM WATERBODIES
The time-lines of fish mercury concentrations in all three Area 2 impoundments (Stephens Lake, Long
Spruce forebay, Limestone forebay) conform to the well-established pattern for boreal reservoirs
(Schetagne et al. 2003; Bodaly et al. 2007; see Figure 5.5.4-11). This conformity is apparent despite the
fact that concentrations for the first 8–11 years after reservoir creation are lacking for Stephens Lake and
the Long Spruce forebay, and the exact extent and timing of potential maximum concentrations remains
unknown.
Mercury concentrations in pike and Walleye from all Area 2 reservoirs continued to decline
(Stephens Lake and Long Spruce forebay) or started to decline (Limestone forebay) after 1994. Similar
declining trends were also observed for other fluvial lakes on the Nelson River, such as Split Lake
(Section 5.5.3.3.1) and Gull Lake, and for the lower Nelson River itself (Section 5.5.3.3.5). Mean
concentrations in pike and Walleye from all these waterbodies were at or mostly below 0.2 ppm by
approximately 2005. A similar temporal pattern of mercury concentrations exists for Lake Whitefish
although it is less pronounced and the number of waterbodies with sample frequencies and fish sample
sizes comparable to the two piscivorous species is lower. Similar to pike and Walleye, whitefish in
on-system waterbodies of Area 2 also reached minimum concentrations of 0.03-0.08 ppm in 2004/2005.
DECEMBER 2015
5.5-50
The decline in mercury concentrations for pike and Walleye from Split and Gull lakes, and the lower
Nelson River is particularly remarkable because these waterbodies were not directly affected by flooding,
and changes in concentration cannot be explained by small fish sample sizes and/or differences in fish
length for arithmetic means. It is possible that starting in the mid-1990s the lower concentrations in pike
and Walleye from all waterbodies on the Nelson River were at least partially driven by an ecological event
unrelated to hydrological development. Rainbow Smelt, an invasive fish species first recorded in Lake
Winnipeg in 1990, expanded its distribution into Split Lake and the Area 2 forebays somewhere between
1994 and 1996 (Remnant et al. 1997). The species rapidly increased in abundance and numerically
dominated all forage fish species in the diet of pike and Walleye from Split and Gull lakes and the three
reservoirs (NSC 2012). Smelt mercury concentrations, measured for maximally five years in several
waterbodies, were substantially (up to 3 times) lower than those of Spottail Shiner (Notropis hudsonius)
and Emerald Shiner (Notropis atherinoides), common forage species in the diet of pike and Walleye prior
to the arrival of smelt (KHLP 2012). It seems that the two piscivores switched their diet from fish species
with relatively high mercury concentrations to a species with a relatively low concentration in response to
changes in relative abundance. As a possible result, mercury concentrations of pike and Walleye in the
on-system waterbodies invaded by smelt declined and the rate of decline in the three reservoirs
increased. There are no off-system lakes with known smelt populations for comparative purposes.
Current (2009–2014) standard means of pike and Walleye from reservoirs and other on-system
waterbodies (Split and Gull lakes, lower Nelson and Aiken rivers) range from 0.24 ppm in pike from the
Limestone forebay to 0.41 ppm in Walleye from Split Lake and are mostly significantly higher compared
to 2005. With the exception of Split Lake, concentrations in whitefish have not followed the post-2005
increase observed for the two piscivores. Again, this difference is partially a result of small fish sample
sizes (Stephens Lake) and/or lack of post-2005 samples (Long Spruce forebay). Current (2009–2013)
standard means for whitefish, available only for Split and Stephens lakes and the lower Nelson River,
range from 0.046 ppm to 0.102 ppm.
The current means for Walleye from the on-system waterbodies are mostly statistically similar to those
from their conspecifics from off-system Assean Lake, whereas means of pike and whitefish are
significantly higher for approximately half of the available yearly comparisons. These differences among
the three species are partially caused by the significant difference between the mean concentrations of
Walleye from Assean Lake in 2010 and 2013 (Figure 5.5.3-9 and Table 5.5.4-2). To minimize the effect of
annual variability in mercury concentrations and other stochastic effects associated with results for a
single waterbody (i.e., Assean Lake), all recent data for four off-system CAMP reference lakes within the
ROI were used to obtain an estimate of current background concentrations (see Section 5.5.4.4.2).
DOWNSTREAM EFFECTS OF HYDROELECTRIC DEVELOPMENT ON FISH MERCURY
CONCENTRATIONS IN AREA 2
Based on the data presented in Section 5.5.3.3.1 and the discussion in Section 5.5.3.4.2, there is no clear
evidence that potential exports of mercury and/or methylmercury, either suspended in water or
incorporated into biota from flooded waterbodies upstream of the Kelsey GS (i.e., LWR) or on the
Rat/Burntwood River (i.e., CRD) had a measurable effect on fish mercury concentrations in Split Lake.
Because large waterbodies on a diversion route act as methylmercury sinks and greatly reduce further
export downstream (Schetagne et al. 2003; for more detail see Section 5.5.4.4.3), it can be assumed that
DECEMBER 2015
5.5-51
fish mercury concentrations in Area 2 on-system waterbodies downstream of Split Lake were not affected
by the potential export of methylmercury in water, particular organic matter, and plankton from CRD/LWR.
There also is little evidence for a downstream effect of reservoir flooding on fish mercury concentrations
within Area 2. At least none of the detailed temporal changes in concentrations of the three focal species
from any of the three reservoirs can be traced in the respective concentrations in fish from the waterbody
immediately downstream. For example, the increase in concentration of whitefish from the Long Spruce
forebay between 1993 and 1996 was not observed in their conspecifics from the Limestone forebay over
the same time period. Also, the increase in mercury concentrations between 1990/1991 and 1994 and the
downward trend in concentrations between 1994 and 2001 in fish from the Limestone forebay was not
reflected in the results from the lower Nelson River over the same time periods, although the available
data for comparisons are limited. These patterns (or lack thereof) do not exclude the possibility of a
downstream effect, but if it exists, it must be relatively small.
DECEMBER 2015
5.5-52
5.5.4
Area 3: Southern Indian Lake to Split Lake Inlet
As part of CRD, a control structure was placed at Missi Falls on the northern outlet of SIL, a large
2
(1,977 km ) multibasin lake through which the Churchill River flowed (Rosenberg et al. 1987). Upon
completion on October 15, 1976, the Missi Falls Control Structure (CS) raised the water level of SIL by
approximately 2.7 m above its long-term mean (see Section 4.3.3.2.3), increasing the lake area by
2
approximately 136 km , and diverting the majority of the upper Churchill River flow into the Rat/Burntwood
River system. Water was diverted via a channel constructed between South Bay in the southwestern part
of SIL and Isset Lake at the headwaters of the Rat River in the Nelson River basin. A CS was built at
Notigi Lake to regulate flows down the Rat River valley.
Construction activities for the Notigi CS were initiated in winter 1972/1973. Discharge from Notigi Lake
was stopped over the period from May 1974 to November 1975 to retain local runoff until water levels in
2
the Rat River valley and SIL were similar. Following impoundment, approximately 453 km were flooded
which caused an approximate doubling of the combined surface area of lakes in this reach, including
Issett, Karsakuwigamak, Pemichigamau, Rat, Mynarski, and Notigi lakes. The greatest flooding and
change in surface area occurred in the Issett Lake area, which increased from approximately 4.6 to
2
2
119 km and Rat Lake which increased from approximately 93.6 to 241 km . Diversion of the Churchill
River was initiated in June 1976, and the cofferdam at the Notigi CS was removed in September 1976.
2
Due to the extensive amount of flooding from CRD (approximately 293 sq mi or 759 km in Areas 3 and
4), fish mercury concentrations in some lakes along the diversion route had the most substantial
increases in the ROI. All of the lakes sampled for fish mercury in Area 3 (both on-system and off-system)
are shown in Map 5.5.4-1
5.5.4.1
Key Published Information
Mercury concentrations in several fish species from primarily commercial catches from Area 3
waterbodies between 1970–1972 were first compiled by Bligh (1970, 1971) and Derksen (1978a, b,
1979). Mercury data for fish sampled commercially, including analyses of individuals from diversion route
lakes through to 1979 were summarized in Bodaly and Hecky (1979) and McGregor (1980). Commercial
data from composite fish samples through to 1985 were compiled as part of the Canada-Manitoba
Agreement on the Study and Monitoring of Mercury in the Churchill River Diversion (DFO 1987; Rannie
and Punter 1987 (data to 1983); see Section 5.5.1.2). Bodaly and Hecky (1979) also reported on mercury
concentrations of Lake Whitefish at Southern Indian and Issett lakes in 1975 and 1978.
Several publications include mercury data from individual fish based on survey samples collected at SIL
and diversion route lakes from 1982–1985 under the auspices of the 1983 Canada-Manitoba Agreement
(Bodaly et al. 1984a; Strange 1985; Green 1986; Bodaly et al. 1987; Derksen and Green 1987; Hecky et
al. 1987). In addition to the data determined from the 1983-85 fish collections, Derksen and Green (1987)
analysed all mercury concentrations existing at the time for pike, Walleye, and Lake Whitefish from
11 Area 3 lakes.
DECEMBER 2015
5.5-53
Bodaly et al. (1987) reported on mercury concentrations in two forage fish species (Spottail Shiner and
Yellow Perch) sampled from several lakes (SIL Issett, Granville, Notigi, Mynarski, Footprint) in 1981 and
1982. In addition to FEMP studies outlined in Section 5.5.1.2, Ramsey (1990) provided mercury
concentrations in Yellow Perch captured in Granville Lake and transferred to holding pens in Methyl Bay
(SIL) to measure methylation rates in flooded zones. Also as part of FEMP, Baker and Davies (1991)
compiled information on fish mercury concentrations in lakes harvested by NFA communities. Fish
mercury concentrations continued to be measured for Rat and Threepoint lakes between 1986 and 1989
by Manitoba Natural Resources (Green 1990).
Fish mercury data from SIL and several diversion route lakes were collected on multiple occasions
between 1992 and 2005 in conjunction with the MMMR Program and successor programs (see Section
5.5.1.2; Strange 1993, 1995; Strange and Bodaly 1997, 1999; Jansen and Strange 2007a). In 2007/2008,
monitoring of mercury in fish from lakes on the CRD route (SIL, Issett, Leftrook, Notigi, Threepoint, and
Wuskwatim lakes) was conducted as part of Manitoba Hydro’s environmental studies (Jansen 2010a).
Fish mercury concentrations continue to be monitored in Area 3 at SIL (2 areas) and Rat Lake on a threeyear rotational basis, and annually at Threepoint and Leftrook lakes under Manitoba/Manitoba Hydro’s
CAMP. Results for sampling conducted in 2010, when monitoring was initiated in this area under CAMP,
are presented in CAMP (2014).
Summaries of fish mercury data from northern Manitoba often focus on waterbodies on the CRD route
(Area 3) and include assessments of the effects of hydroelectric development on mercury concentrations
and associated fisheries impacts (Bodaly and Hecky 1979; McGregor 1980; Bodaly et al. 1984a, b;
Strange et al. 1991; Strange and Bodaly 1999; Bodaly et al. 2007; Jansen and Strange 2007a). The
temporal scope of these reviews was limited to the data available at the time and the statistical analysis
chosen for determining the time of return to background mercury concentrations in one earlier review
(Bodaly et al. 2007) resulted in conclusions that partially differ from the current report (for details, see
Section 5.5.4.4.3).
Johnston et al. (1991) developed and tested predictive models relating reservoir flooding to fish mercury
concentrations for reservoirs using fish mercury data from SIL and several of the diversion route lakes.
More recently, Bodaly et al. (2007) used similar, updated data as part of an analysis of post-impoundment
trends in fish mercury concentrations in boreal Manitoba reservoirs.
DECEMBER 2015
5.5-54
Hudson Bay
Churchill
Thompson
Moss
Lake
SIL
Area 5
Le Clair
Lake
SIL
Area 4
Southern
RCEA
Area 3
Missi Falls
Control Structure
Barrington
Gauer
Lake
Indian
SIL
Area 2
Lake
Lake
493
Cousins
Lake
O-Pipon-Na-Piwin Cree Nation
South Indian Lake
Opachuanau
Lake
SIL
Area 6
Issett
Lake
Baldock
Lake
Leaf Rapids
Karsakuwigamak
Lake
Pemichigamau
Lake
Granville
Lake
Mynarski
Lakes
Rat Lake
Leftrook
391
Osik L.
Notigi Lake
Notigi Control
Structure
Wapisu
Lake
Lake
280
Footprint Nisichawayasihk Cree Nation
Nelson House (NAC)
L.
Threepoint
Lake
Kelsey
G.S.
Mystery
L.
Thompson
6
Ospwagan
Wuskwatim
L.
Lake
Wuskwatim G.S.
NOTE: (NAC) Northern Affairs Community
Legend
Control Structure
Focal Waterbody
Highway
Southern Indian Lake (SIL) Historical Geographic Area
DATA SOURCE:
Province of Manitoba, Government of Canada, North/South Consultants and
Manitoba Hydro.
CREATED BY:
COORDINATE SYSTEM:
Assessment
0
0
10
20 Kilometers
10
20 Miles
DATE CREATED:
REVISION DATE:
22-OCT-15
05-DEC-15
VERSION NO:
QA/QC:
Waterbodies with Information
on Mercury in Fish
RCEA Area 3
1.0
Map 5.5.4-1
5.5.4.2
New Information and/or Re-analysis of Existing Information
The current assessment is based on the updated analysis of all available data from 1969 to 2014. With
mercury concentrations for almost 27,000 fish of 18 species, Area 3 represents more than half of all
mercury analyses for individual fish in the entire ROI (Table 5.5.1.-1). In addition to this, more than
300 analyses for composite, commercial fish samples exist for Area 3. The commercial data were used
mainly for years predating-CRD and when no results based on individual fish were available. In these
cases, some of the published yearly means were recalculated for years with multiple composite samples
that were reported separately. Almost 90% of all individual mercury data for Area 3 are for Cisco, Lake
Whitefish, pike, and Walleye, and almost 60% are just for pike and Walleye.
Six on-system lakes and one off-system lake were selected as focal waterbodies for detailed presentation
in the following discussion due to the presence of data in a time-series with sufficient resolution to allow
conclusions on the evolution of fish mercury concentrations during and following flooding (i.e., Southern
Indian, Issett, Rat, Notigi, Threepoint and Wuskwatim lakes). In addition, data are available from several
off-system lakes both prior to and after CRD to provide a record of among-lake variability in fish mercury
concentrations independent of the effects of hydroelectric development. Leftrook Lake is the off-system
reference lake with the longest and most complete record of post-CRD fish mercury concentrations in the
entire ROI and it was included as a focal lake. The waterbody with the most extensive data set and on
which most of the early studies on fish mercury were focused is SIL. Southern Indian Lake also is the only
waterbody in Area 3 for which there are fish mercury data from different areas of the lake, illustrating
among-area differences in fish mercury concentrations.
5.5.4.3
PRE-CRD BASELINE MERCURY CONCENTRATIONS
The majority of the fish mercury monitoring in Area 3 that pre-dates CRD (i.e., 1969–1974) relates to
commercially caught fish. This includes mercury data from both on-system and off-system lakes, such as
Southern Indian, Gauer, Baldock, Barrington, Opachuanau, and Wuskwatim lakes (Derksen 1978a, 1979;
Bodaly and Hecky 1979; McGregor 1980; Bodaly et al. 1984; DFO 1987; Table 5.5.4-1). In addition to the
mercury concentrations from commercial catches, pre-CRD mercury data exist for five samples of
24-25 Lake Whitefish from Cousins and Issett lakes and Areas 2, 4, and 6 of SIL collected in 1975.
Although the time of collection falls after the start of impoundment of SIL and Issett lakes, and the
flooding at Cousins Lake, it predates the start of the major ponding of SIL in June 1976. Furthermore, the
mercury concentration in the relatively large whitefish sampled in 1975 would not have been affected
(or only marginally) by any ‘new’ mercury potentially accumulated during the early flooding stage. This
conclusion is supported by findings that mercury concentrations in the muscle of large fish respond more
slowly to increased mercury availability, as in the case of reservoir flooding, than small fish
(Harris and Hutchinson 2009).
Based on data from commercial fish, pre-CRD mercury concentrations were similar between on-system
and off-system waterbodies with means ranging from 0.06–0.13 ppm in Lake Whitefish, 0.17–0.36 ppm in
DECEMBER 2015
5.5-56
Northern Pike and 0.19–0.36 ppm in Walleye (Table 5.5.4-1). Because of the composite nature of
commercial samples (see Section 5.5.1.4), the typically small sample size and unknown length of the fish
included in the sample, statistical comparisons among commercial samples are rarely feasible.
Comparisons to means based on individual fish are also problematic. Therefore, the conclusion of
equality in fish mercury concentrations between on-system and off-system waterbodies is tentative for
comparisons of individual lakes, and is mainly based on the weight of evidence for the entire dataset.
Table 5.5.4-1:
Mean (range) Mercury Concentrations, Parts-per-Million, for Northern Pike,
Walleye, and Lake Whitefish from On-System and Off-System Waterbodies
in Area 3 for the Years Predating Churchill River Diversion (1969–1974,
except Wuskwatim Lake, 1970–1976)
Off-system
Location
n
Mean
On-system
Location
Range
n
Mean
Range
Northern Pike
Baldock Lake
1
0.17
-
Opachuanau Lake
2
0.31
0.31–0.31
Barrington Lake
3
0.36
0.33–0.39
SIL, Area 6
3
0.29
0.26–0.32
Gauer Lake
1
0.31
-
4
0.35
0.22–0.43
1
Granville Lake
Walleye
Baldock Lake
2
0.23
0.18–0.27
Opachuanau Lake
3
0.19
0.17–0.21
Barrington Lake
3
0.21
0.13–0.26
SIL, Area 6
3
0.23
0.19–0.28
Gauer Lake
2
0.22
0.18–0.25
Wuskwatim Lake
6
0.34
0.25–0.44
Granville Lake
5
0.23
0.10–0.30
Lake Whitefish
Baldock Lake
1
0.12
-
Opachuanau Lake
1
0.06
-
Barrington Lake
1
0.07
-
SIL, Area 6
4
0.06
0.02–0.11
Gauer Lake
1
0.13
-
Wuskwatim Lake
1
0.08
-
Granville Lake
1
0.07
-
Note: All data are for fish from composite samples of commercial catches; n indicates the number of years with data;
occasionally the concentration for a particular year represents a mean based on two or more composite samples.
1. Granville Lake is located just west of Area 3 and is included for comparative purposes; it was included because of its
long-term data set on fish mercury concentrations, including pre-CRD data (see Figure 5.5.4-9).
Considering the problems with comparing mercury concentrations from composite samples and those
based on individual fish, it is noteworthy that the arithmetic means measured in individual whitefish from
areas 2, 4, and 6 of SIL in 1975 (range of 0.046 to 0.070 ppm) are almost identical to the mean of
0.06 ppm of the six commercial samples analysed prior to flooding (1969–1973). The standard mean of
DECEMBER 2015
5.5-57
0.103 ppm for individual whitefish caught in 1975 from Cousins Lake, an off-system lake, also closely
matches the mean for commercial samples measured in four off-system waterbodies (Table 5.5.4-1). The
survey sample mean of 0.146 ppm from Issett Lake in 1975 is slightly outside the range of concentrations
from commercial samples of whitefish collected from the lakes listed in Table 5.5.4-1 and is significantly
higher than the mean for each of the four survey samples from SIL in 1975. Perhaps by the late summer
of 1975 the rate of mercury accumulation in whitefish from Issett Lake had started to increase due to the
flooding that occurred slowly from May 1974 to November 1975 (see Section 5.5.4.3.2). The data for
whitefish from Issett Lake in 1975 were not used in any calculations of pre-CRD mercury baseline
concentrations.
POST-CRD CHANGES IN MERCURY CONCENTRATIONS
Post-CRD mercury data have been collected for approximately 27,000 fish from almost 100 waterbodies
in Area 3. As illustrated by the results for pike, most of the data are from approximately 20 lakes and for
years between 1978 and 1994 (Appendix 5.5.4A). Mean mercury concentrations of pike in several lakes
other than the focal lakes, such as Apussigamasi, Karsakuwigamak, Moss, East Mynarski, West
Mynarski, Mystery, Opachuanau, Osik, Ospwagon, Pemichigamau, and Wapisu, have exceeded 1.0 ppm
1
in at least one year post-CRD (Figure 5.5.4A-1 ). All of these lakes have been flooded to various degrees
by CRD.
Subsequent sections will first provide a detailed description of the time series of fish mercury observed for
each focal lake. This will be followed by a general discussion of the evolution of fish mercury
concentrations in Area 3, including comparisons to standards and guidelines.
5.5.4.3.1
Southern Indian Lake
Southern Indian Lake was flooded by approximately 7% of its original area starting in August 1973 but the
majority of flooding took place between June and October 1976. Year 1976 was considered as year 1
post-flooding. During studies conducted by DFO in the 1970s, the lake was divided into six areas based
in part on pre and post flooding and diversion differences in water flow (Bodaly and Hecky 1979). Mercury
concentrations for pike, Walleye, Lake Whitefish, Burbot and Longnose Sucker (Catostomus catostomus)
from different areas of SIL (see Map 5.5.4-1) are provided in Appendix 5.5.4B. The following discussion
focuses on Area 6 of SIL because of its relatively good overall data record and the presence of pre-CRD
data. Area 6 is also referred to as South Bay and represents the furthest downstream part of the lake
prior to the construction of the diversion channel.
Mercury concentrations in in Lake Whitefish and Walleye from Area 6 increased relatively rapidly after
CRD flooding, but took longer to reach maximum values in pike. Whitefish reached a maximum mean of
1
Tables, figures, and maps with a letter in their numbers (e.g., A) can be found in the appendices for this chapter.
DECEMBER 2015
5.5-58
0.24 ppm in 1979, four years after flooding (Figure 5.5.4-1). The maximum concentration was four times
higher than the average pre-CRD concentration (i.e., IF = 4.0; Table 5.5.4-3). Concentrations decreased
after 1979 to reach a minimum of 0.026 ppm by 2005, resulting in a return time of 26 years
(Table 5.5.4-3). Concentrations have remained similar since that time (Figure 5.5.4-1). The post-CRD
minimum was less than half of the mean pre-CRD concentrations of 0.06 ppm (Table 5.5.4-3).
Mean concentrations in Walleye from Area 6 reached a maximum of 0.80 ppm three years after flooding
and, in contrast to whitefish, fluctuated substantially until reaching a secondary peak of 0.78 ppm in 1982
(Figure 5.5.4-1). Thereafter, mercury concentrations declined, again with many ups and downs to reach a
minimum of 0.33 ppm in 2005. The corresponding return time was 27 years and the IF was 3.5
(Table 5.5.4-3). The post-CRD minimum was substantially higher than the pre-CRD mean
(from commercial samples) of 0.23 ppm. Mean concentrations increased significantly from 2005 to 2007
and remained similar thereafter.
1.4
CRD
flooding
SIL, Area 6
1.2
Pike
Walleye
Whitefish
1.0
*
*
0.8
*
* *
*
*
*
0.6
*
*
*
*
*
0.4
*
*
0.2
*
*
*
*
*
0.0
70
19
75
19
80
19
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
mercury concentration was not significant and the arithmetic mean was used. The stippled line indicates the 0.5 ppm Health Canada
standard for retail fish.
Figure 5.5.4-1:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From Area 6
(South Bay) of Southern Indian Lake for 1969–2013
DECEMBER 2015
5.5-59
Northern Pike had the highest post-CRD mercury concentration of all fish species analyzed from SIL.
After a steady increase from a pre-CRD mean of 0.29 ppm, pike from Area 6 reached a maximum
concentration of 1.1 ppm in 1984, nine years after flooding (Figure 5.5.4-1). Thereafter, concentrations
decreased rapidly within the next year and then more steadily until reaching a minimum of 0.32 ppm in
2005, which was just slightly higher than the pre-CRD mean. The return time was 24 years and the IF
was 3.8 (Table 5.5.4-3). Similar to Walleye, concentrations increased after 2005 and were significantly
higher for all three sampling years until 2013 (Figure 5.5.4-1).
Although the general post-CRD pattern of rise and fall in fish mercury concentrations was similar for the
five different geographical areas sampled in SIL, and for the samples representing a mix of fish from
different areas (designated ‘No area’ in all respective figures), sometimes substantial differences existed
when comparing year-specific concentrations and rates of increase and/or decline in concentrations. For
example, maximum mercury concentrations in pike from other areas of SIL were often significantly lower
than from Area 6, never exceeding 0.8 ppm except for fish from ‘No area’ (Figure 5.5.4B-1).
The decline of concentrations in pike and Walleye prior to 2005 in other areas of SIL was much less
consistent compared to the pattern observed for Area 6 (see Figures 5.5.4B-1 and 5.5.4B-2). This may
partially have been a result of the generally smaller sample sizes in areas other than 4 and 6. Because of
the lack of pre-CRD data for all areas except Area 6, the proportional increase (i.e., IF) could not be
calculated for any other area and was estimated only for Area 4 by using pre-CRD concentrations from
Area 6 (Table 5.5.4-2). For Lake Whitefish, standard means recorded in 1975 from Areas 2, 4, and 5
were all similar and only marginally lower than the 0.07 ppm mean for whitefish from Area 6
(Figure 5.5.4B-3). Whitefish in Areas 4 and 5 reached similar maximum concentrations of 0.22 and
0.26 ppm, representing increases of approximately four times from pre-flood levels, which was similar to
Area 6. In contrast, whitefish from Area 2 reached a lower maximum concentration of 0.10 ppm five years
post-flooding.
One other notable difference in mercury concentrations of fish from the five areas of SIL existed for
Walleye in Areas 4 and 6. For all sampling years (starting in 1979 for Area 4), mean concentrations in fish
from Area 6 were higher than those from Area 4, and since 1998/1999 the difference has been significant
(Figure 5.5.4B-2). Furthermore, mercury levels in Walleye from Area 5 and ‘No area’ (the only other areas
with a comparable dataset to Areas 4 and 6) have also been lower than those from Area 6. This has been
observed since 1989, and concentrations in Area 4 and ‘No area’ have been at or below pre-CRD
concentrations for Area 6 since 1996 (Figure 5.5.4B-2).
Species other than Lake Whitefish, Northern Pike, and Walleye have been less frequently analyzed for
mercury, and interpretation of their mercury concentrations and the impact of CRD is more difficult.
Concentrations in Burbot, a piscivorous species that is occasionally consumed domestically, remained
consistently lower than those in pike and Walleye from SIL (Figure 5.5.4B-4). There is some indication
that concentrations increased post-CRD to reach maximums of 0.27–0.48 ppm between 1982 and 1986
and then declined. Mean concentrations in Burbot were low (0.15 ppm) when last sampled in Areas 5 and
6 in 1998 (Figure 5.5.4B-4). Longnose Sucker did not show an obvious increase in mercury
concentrations post-CRD when first measured in 1982, and the standard means of fish from Areas 2, 4,
and 5 ranged from 0.07-0.11 ppm (Figure 5.5.4B-5).
DECEMBER 2015
5.5-60
In addition to the empirical data for fish captured pre-CRD and for several decades post-CRD from SIL,
the increase in mercury availability following lake flooding has also been demonstrated experimentally for
Yellow Perch. Mean muscle mercury concentrations of age 1+ fish (54–65 mm total length at the end of
the experiment) from Granville Lake almost doubled from 0.043 to 0.083 ppm within 57 days after transfer
into enclosures within the flooded zone of SIL Area 6 in the summer of 1989 (Ramsey 1990). The posttransfer values were similar to mean mercury concentrations of 0.06–0.11 ppm measured in feral 1-yearold Yellow Perch (58–72 mm total length) from SIL Areas 4, 5, and 6 in 1982 (Bodaly et al. 1987).
5.5.4.3.2
Issett Lake
The Issett Lake area was flooded by approximately 2,470% of its original area, greatly expanding the
footprint of the reservoir to the west of the original lake location. Impoundment occurred in stages
between May 1974 and November 1975, and from June to October 1976. Year 1975 was considered as
year 1 post-flooding.
Mercury concentrations in Lake Whitefish increased significantly from 0.15 ppm for the one available preCRD survey sample in 1975 to a maximum of 0.32 ppm in 1978 (Figure 5.5.4-2). However, caution is
warranted regarding the results for 1975 and 1978. The standard mean in 1975 was potentially elevated
because of initial flooding effects (see Section 5.5.4.3). The arithmetic mean for 1978 was based on only
five small (< 310 mm) fish, and may have underestimated or been not representative of the average
concentration of the population at the time. For these reasons the IF of 2.2 (Table 5.5.4-3) is also
questionable. Concentrations decreased after 1978 to 0.21 and 0.17 ppm in years 1982 and 1983
(Figure 5.5.4-2), the latter mean being significantly different from the maximum.
Concentrations in whitefish declined steadily each year from 1983 to 1986, remaining similar until 1988,
and were significantly lower when sampled again in 1996 and 1998 (approximately 0.04 ppm). A
minimum concentration of 0.023 ppm was observed in 2005, significantly lower than any of the previous
means and the mean for the last sample in 2008. The return time was 27 years (Table 5.5.4-3).
Walleye had a maximum mercury concentration of 1.52 ppm based on five fish collected in 1978, four
years after flooding (Figure 5.5.4-2). Concentrations decreased rapidly to 0.60 ppm by 1985, fluctuated
substantially until 1996, then declined steadily to reach a minimum of 0.34 ppm in 2005. Concentrations
were statistically similar to those in 2005 when last sampled in 2008. The peak concentration
corresponded to an increase factor of 5.5 and the return time was 20 years (Table 5.5.4-3).
Mercury concentrations of pike increased from 1978 to 1983, reaching a maximum of 0.85 ppm nine
years post-flooding (Figure 5.5.4-2). The maximum corresponds to an IF of 2.8 (Table 5.5.4-3).
Concentrations steadily declined thereafter, except for a transient increase in 1992, and reached a
minimum of 0.36 ppm in 2005. Identical to the pattern for Walleye, concentrations were statistically similar
to those recorded in 2005 when last sampled in 2008. The return time was 23 years (Table 5.5.4-3).
DECEMBER 2015
5.5-61
2.0
CRD
flooding
Issett Lake
Pike
Walleye
Whitefish
*
1.5
1.0
*
*
*
*
0.5
*
*
*
*
*
0.0
75
19
80
19
85
19
90
19
95
19
00
20
05
20
Year
Figure 5.5.4-2:
Mean (95% Confidence limits) Length Standardized Muscle Mercury
Concentrations of Northern Pike, Walleye, and Lake Whitefish From Issett Lake
for 1975–2008
5.5.4.3.3
Rat Lake
Rat Lake was flooded by approximately 158% of its original area. Impoundment occurred in stages
between May 1974 and November 1975, and from June to October 1976. Year 1975 was considered as
year 1 post-flooding.
Mercury concentrations in Lake Whitefish were highest (0.40 ppm) for the first post-CRD sample in 1978
(Figure 5.5.4-3); however, it is likely that the sample of five very large (mean fork length = 439 mm) fish
did not well represent the average concentration of the population. Therefore, the second highest
concentration of 0.25 ppm observed in 1984 was used as the peak concentration, increasing the time to
reach the maximum from four to 10 years and resulting in an IF of 4.1 instead of 6.6 (Table 5.5.4-3).
Mercury concentration fluctuated between 0.18 and 0.22 ppm from 1985 to1989, then rapidly decreased
to a minimum of 0.03 ppm in 1994. Subsequently concentrations have significantly increased to
approximately 0.07 ppm in 1996 and 1999. More recent concentrations are only available for samples of
2-3 fish.
DECEMBER 2015
5.5-62
3.0
CRD
flooding
Rat Lake
2.5
Pike
Walleye
Whitefish
2.0
1.5
1.0
0.5
*
*
*
0.0
75
19
80
19
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
Figure 5.5.4-3:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From Rat Lake
for Years 1978–2005
Mercury concentrations in pike and Walleye from Rat Lake were almost identical both in absolute
concentrations and in the post-CRD pattern of decline for most years of the available record
(Figure 5.5.4-3). Only for the first few years, when sample sizes were small (22–26 fish) and included a
commercial sample for pike, did the timeline of mercury levels diverge between the two species.
Concentrations in Walleye were highest (2.4 ppm) when first sampled in 1978 four years after flooding,
resulting in an IF of 8.7 (Table 5.5.4-3). The maximum concentration used for pike was the standard
mean of 1.69 ppm recorded four years post-flooding and representing an IF of 5.7 (Table 5.5.4-3). A
mean of 2.14 for five commercial samples for 1977 and a value of 2.32 for a single commercial sample in
1980 suggest that the maximum concentration in pike may have been higher. The decline in mercury
concentrations from 1985 onwards was almost identical for both species (Figure 5.5.4-3), including a
transient increase from 1992–1994, a minimum of 0.48 ppm (pike) and 0.41 ppm (Walleye) in 2005, and
the subsequent increase, which was significant for Walleye in 2010 and 2013. The return time was
21 years for pike and 26 years for Walleye.
DECEMBER 2015
5.5-63
5.5.4.3.4
Notigi Lake
Notigi Lake was flooded by approximately 324% of the original area of lakes and creeks that became part
of the reservoir. Impoundment occurred in stages between May 1974 and November 1975, and from
June to October 1976. Year 1975 was considered as year 1 post-flooding.
Mercury concentrations in Lake Whitefish were first available in 1980 (i.e., six years after flooding) and
the mean (0.12 ppm), which was based on six relatively large (mean fork length = 421 mm) fish, may not
well represent the population average. It is likely that the maximum concentration of whitefish in Notigi
Lake was not captured in monitoring programs. This is corroborated by the absence of an obvious peak in
concentrations and the fact that the observed maximum of 0.27 ppm was measured 11 years
post-flooding (Figure 5.5.4-4). Both these patterns are unusual for the evolution of mercury
concentrations in boreal reservoirs (see Section 5.5.4.4.3), Whitefish mercury concentrations decreased
significantly from 1985 to the next sample in 1999 (0.07 ppm), and then remained statistically similar until
2007, when last measured. Recognizing the shortcomings in the data record associated with the
observed maximum concentration (see above), the IF was 4.3 and the return time was 18 years
(Table 5.5.4-3).
Walleye had a maximum mean of 2.90 ppm recorded for a sample of four fish in 1980, six years after
flooding (Figure 5.5.4-4). Further support for such a high concentration comes from a commercial sample
for the same year with a mean of 2.58 ppm (DFO 1987). However, both these concentrations come from
relatively large fish (mean fork length of the survey sample = 453 mm) and to obtain a more realistic and
comparable mean concentration, data for 1980 were combined with the 29 fish sampled in 1981, resulting
in a standard mean of 1.86 ppm. Concentrations decreased rapidly thereafter to 0.63 ppm in 1988,
fluctuated between 0.55 ppm and 1.01 ppm for the following four samples until 2002, and reached a
minimum of 0.45 ppm when last sampled in 2007. The minimum was significantly lower than the means
for 2001 and 2002. The IF was 6.7 and the return time was 18 years (Table 5.5.4-3).
Mercury concentrations of pike reached a maximum of 1.95 ppm in 1980 (Figure 5.5.4-4), corresponding
to an IF of 6.5 (Table 5.5.4-3). Concentrations decreased relatively slowly and included a transient
increase to 1.69 ppm in 1988. Thereafter, the decrease in concentration was more steady, reaching a
minimum of 0.59 ppm in 2002. The minimum was not significantly different from the preceding mean for
2001 and the last recorded mean in 2007. The return time was 21 years (Table 5.5.4-3).
DECEMBER 2015
5.5-64
3.0
* 3.8
CRD
flooding
Notigi Lake
2.5
Pike
Walleye
Whitefish
2.0
*
*
*
1.5
*
*
*
1.0
*
*
0.5
*
*
0.0
75
19
80
19
85
19
90
19
95
19
00
20
*
05
20
Year
mean was used. A number denotes an upper CL not shown as a bar. The mean for pike in 1977 is from commercial samples ; the
stippled line indicates the 0.5 ppm Health Canada standard for retail fish.
Figure 5.5.4-4:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From Notigi Lake
for 1977–2007
5.5.4.3.5
Threepoint Lake
Threepoint Lake was flooded by approximately 44% of its original area between September 1976 and
August 1977; 1977 was considered as year 1 post-flooding.
Mercury concentrations in Lake Whitefish were highest (0.39 ppm) for the first sample available post-CRD
in 1980 (Figure 5.5.4-5). Subsequent means have been almost half of this values and it is likely that the
only five relatively large (mean fork length = 429 mm) did not adequately represent the average
concentration of the population in 1980. Similar to the approach for Walleye from Notigi Lake
(see Section 5.5.4.3.4), data for fish collected in 1980 and 1981 (which represented the second highest
concentration) were combined to estimate a maximum concentration of 0.251 ppm which was assigned to
1981. This resulted in an IF of 4.1 (Table 5.5.4-3). Mercury concentration decreased slowly until 1994,
then more rapidly to less than 0.1 ppm in 1996 and 1998. Subsequently, slightly higher means were
based on small (< 8) fish sample sizes until yearly sampling from 2011–2014 indicated stable
DECEMBER 2015
5.5-65
concentrations of approximately 0.06 ppm (Figure 5.5.4-5). These four means were not significantly
different from the mean of 0.13 ppm for 2005, which represented only four fish and was associated with
large confidence limits. The return time was 30 years (Table 5.5.4-3).
In contrast to SIL and similar to Rat Lake, mercury levels in Walleye and Northern Pike from Threepoint
Lake were very similar both in absolute concentrations and in the post-CRD pattern of increase and
decline. Both species reached similar maximum concentrations of 1.76 ppm (pike) and 1.65 ppm
(Walleye) in 1983, seven years after flooding (Figure 5.5.4-5), representing IFs of 5.9 and 6.0,
respectively. Concentrations in both species consistently declined to reach nearly identical minimums of
0.38 ppm (pike) and 0.35 ppm (Walleye) in 2005, resulting in return times of 22 years for pike and
18 years for Walleye (Table 5.5.4-3). Thereafter, concentrations increased and became significantly
higher than the 2005 minimum by 2007 (Walleye) and 2010 (pike), and remained elevated (mostly
significantly for Walleye) until last measured in 2014.
2.0
CRD
flooding
Threepoint Lake
1.5
Pike
Walleye
Whitefish
*
*
*
0.52
1.0
0.5
*
*
*
*
*
0.0
75
19
80
19
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
mean was used. A number denotes a CL not shown as a bar. The stippled line indicates the 0.5 ppm Health Canada standard for
retail fish.
Figure 5.5.4-5:
Mean (95% Confidence Limits[CL]) Length Standardized Muscle Mercury
Concentrations of Northern Pike, Walleye, and Lake Whitefish From Threepoint
Lake for 1980–2014
DECEMBER 2015
5.5-66
Fish mercury data for Threepoint Lake also include several other species with mercury data that span
multiple years and with means based on larger sample sizes than for most other lakes. These results
illustrate that mercury concentrations of the mainly planktivorous Cisco are slightly higher, but of similar
magnitude and show a similar pattern of post-CRD decline compared to the benthivorous Lake Whitefish
(Figure 5.5.4-6). Two common catostomids, White Sucker and Longnose Sucker, which diet is best
described as benthivorous detritivors (Ahlgreen 1990a, b) had mercury concentrations generally above
0.4 ppm from 1981–1992 (Figure 5.5.4-6). These values are consistently higher than those measured in
Cisco and whitefish from Threepoint Lake and any other waterbody in Area 3 for a comparable
time-period. Longnose Sucker concentrations were higher (generally significantly) when compared to
their conspecifics from SIL (Figure 5.5.4B-5). Sauger from Threepoint Lake had mercury concentrations
of 1.4–2.3 ppm for four samples measured from 1981–1985 (Figure 5.5.4-6), indicating that this species
can reach similarly high concentrations as the two focal piscivores, pike and Walleye.
2.5
CRD
flooding
Threepoint Lake
*
Sauger
Cisco
White Sucker
Longnose Sucker
2.0
1.5
1.0
*
0.5
*
*
*
*
0.0
75
19
80
19
85
19
90
19
95
19
00
20
05
20
Year
Figure 5.5.4-6:
Concentrations of Sauger, Cisco, White Sucker, and Longnose Sucker From
Threepoint Lake for Years 1981-2005
DECEMBER 2015
5.5-67
5.5.4.3.6
Wuskwatim Lake
Wuskwatim Lake was flooded due to CRD by approximately 44% of its original area between September
1976 and August 1977; 1977 was considered as year 1 post-flooding. Starting in 2007, a generating
station was built just past the outlet of Wuskwatim Lake into the Burntwood River. Impoundment occurred
from October to November 2011, flooding approximately 60 ha in the forebay for a Flood-1% of 0.7%
(Manitoba Hydro and Nisichawayasihk Cree Nation 2003). If the approximately 400 ha of peat islands that
will be flooded within Wuskwatim Lake are included, Flood-1% increases to 5.2%.
Mercury concentrations in Lake Whitefish were highest (0.25 ppm) for the first available sample in 1981,
five years after flooding (Figure 5.5.4-7). Considering the temporal pattern in mercury concentrations of
pike and Walleye, which have a more extensive record during the period immediately following flooding
(see below), it is questionable if the 1981 mean for whitefish adequately represents the maximum
concentration. Nevertheless, it was 3.1 times higher than the only available pre-CRD concentration of
0.08 ppm measured for commercial fish (Table 5.5.4-3). Standard means decreased gradually from 1981
onwards to a minimum of 0.05 ppm in 2005 and then significantly increased in 2007 and 2014
(Figure 5.5.4-7). The return time was 24 years (Table 5.5.4-3).
Mean mercury concentrations in Walleye increased to a maximum of 0.94 ppm within four years after
flooding (Figure 5.5.4-7). The maximum was almost three times the average concentration of 0.34 ppm,
determined from six commercial samples collected pre-CRD (Table 5.5.4-3). Concentrations declined
almost continuously from 1981 onwards and reached a minimum of 0.24 ppm in 1996, remained steady
until 2005 and then significantly increased in 2007 (Figure 5.5.4-7). The concentration in 2014 was still
elevated but not significantly higher than in 2005. The return time was 17 years (Table 5.5.4-3).
Mercury concentrations in Northern Pike concentrations showed a similar increase and decline compared
to Walleye for three consecutive years starting with the first measurement in 1979, but then increased to
a maximum of 1.42 ppm in 1984, seven years after the end of flooding (Figure 5.5.4-7). The maximum
corresponded to an IF of 4.8 (Table 5.5.4-3). Thereafter, concentrations declined rapidly to 0.34 ppm in
1996, remained statistically similar until 2002, and reached a minimum of 0.31 ppm in 2005
(Figure 5.5.4-7). The minimum was significantly lower than the previous mean for 2002 but statistically
similar to the means in 1996 and 1998. Concentrations significantly increased in 2007 compared to the
2005 minimum and were just slightly lower when last sampled in 2014 (Figure 5.5.4-7). However, the last
mean was based on only 12 fish and the associated large confidence limits resulted in a non-significant
differences compared to the 2005 minimum. The return time was 21 years (Table 5.5.4-3).
Mercury concentrations in all three focal species for 2014 were slightly lower and statistically similar
compared to 2007, indicating that the 2011 flooding by the GS has not (yet) measurable affected mercury
bioaccumulation rates in fish from Wuskwatim Lake.
DECEMBER 2015
5.5-68
CRD
flooding
1.6
Wuskwatim Lake
Pike
Walleye
Whitefish
1.2
*
*
0.8
*
*
*
0.4
*
*
0.0
70
19
75
19
80
19
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
mercury concentration was not significant and the arithmetic mean was used. The stippled line indicates the 0.5 ppm Health Canada
standard for retail fish.
Figure 5.5.4-7:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From
Wuskwatim Lake for 1970–2014
5.5.4.3.7
Leftrook Lake
Leftrook Lake is located north of the CRD route and was not affected by flooding. Leftrook Lake is a
CAMP reference lake and the off-system waterbody with the most complete historic record of fish mercury
concentrations in the ROI.
Mercury concentrations in Lake Whitefish were highest (0.05 ppm) when first measured for 36 large
(mean fork length = 424 mm) fish in 1992 (Figure 5.5.4-8). Because the relationship between mercury
concentration and fish length was not significant, only the arithmetic mean is available for the 1992
sample and a direct comparison to the subsequent nine standard means cannot be made. From 1994
onwards until the last sample in 2014, concentrations ranged from 0.018 to 0.037 ppm. Although a few of
the means for this period were significantly different, no consistent temporal pattern in concentrations was
evident, and it is likely that the observed fluctuations in mercury concentrations were part of natural
temporal variability.
DECEMBER 2015
5.5-69
Walleye and pike were first sampled for mercury from 1981–1983 by the DFO Inspections Branch. The
small number of Walleye analysed were relatively large (> 412 mm) headless dressed fish or small
(352 mm) dressed fish. The actual (fork) length of a headless dressed fish is unknown and has been
estimated using a conversion factor. Only arithmetic means could be calculated for the above three
samples. The mean of 0.73 ppm for 1981 likely represents an outlier, although the standard mean for the
first sample of 36 survey fish in 1992 indicates that concentrations have exceeded 0.4 ppm in the past
(Figure 5.5.4-8). From 1994–2014, standard means of Walleye ranged from 0.21–0.29 ppm, have been
associated with very small confidence limits, and have been statistically similar except for the high and
low means observed in 2001 and 2014, respectively.
0.8
*
1.0
Leftrook Lake
Pike
Walleye
Whitefish
0.6
0.4
*
*
0.2
*
*
0.0
75
19
80
19
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
mean was used. The data point without a CL for 1977 is the mean of two commercial samples (0.25 and 0.33 ppm) from 1977 and
1981 which cannot be assigned to a specific year (see Rannie and Punter 1987). A number denotes a CL not shown as a bar. The
stippled line indicates the 0.5 ppm Health Canada standard for retail fish.
Figure 5.5.4-8:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From Leftrook
Lake for 1981–2014
Except for a mean of 0.39 ppm in 2010, mercury concentrations in pike have ranged from 0.19 ppm to
0.27 ppm over the entire record from 1981–2014. Excluding the anomalous result for 2010, standard
means have been statistically similar except for the minimum recorded in 2014, which was significantly
different from the means for 1992 and 2007.
DECEMBER 2015
5.5-70
5.5.4.4
5.5.4.4.1
Mercury concentrations in piscivorous species (i.e., pike and Walleye) from years pre-dating hydroelectric
development in Area 3 were mostly considerably lower than the Health Canada standard of 0.5 ppm for
the commercial sale of fish (Table 5.5.4-1). These relatively low concentrations are even more remarkable
when considering that these data were obtained from commercial catches of fish that likely included a
bias towards larger individuals than most of the fish analysed from post-CRD survey samples. Mean
pre-CRD mercury concentrations of the benthivorous focal species, Lake Whitefish, from commercial
samples (Table 5.5.4-1) but also from the samples of individual fish from SIL, Issett, and Cousins lakes in
1975 (see Section 5.5.4.3) were always much lower than the 0.5 ppm standard and often less than
0.1 ppm.
Following CRD, the concentrations of mercury in Walleye and Northern Pike in all focal lakes and several
other waterbodies in Area 3 increased to (substantially) above 0.5 ppm (see Figure 5.5.4A-1 for pike),
and as discussed in more detail for other areas (see Section 5.5.2.3.1), were often no longer accepted for
marketing in a commercial fishery (Green 1986; Derksen and Green 1987). The period during which
concentrations remained above 0.5 ppm in pike and Walleye varied among lakes, but typically lasted for
two or more decades (see discussion on return times in Section 5.5.4.4.3). Based on the concentrations
of 1.4–2.3 ppm measured in Sauger from Threepoint Lake for 1981–1985, this species may have
experienced increases in post-CRD mercury concentrations at least similar to those observed in the two
focal piscivores, pike and Walleye.
The recent (post-2005) significant increases in mercury concentrations of mainly pike and Walleye
observed for almost all on-system waterbodies in Area 3 have resulted in concentrations that exceed the
Health Canada 0.5 ppm standard for some lakes (e.g., Rat and Threepoint).
The post-CRD increases in mercury concentrations of Lake Whitefish never approached the 0.5 ppm limit
for the commercial sale of fish, reaching maximums of 0.20–0.25 ppm in some lakes. Although quite
variable, the three standard means for 1983–1985 and the arithmetic mean in 1992 for Longnose Sucker
from Threepoint Lake at least suggest that concentrations in non-piscivorous species may have
approached or even exceeded 0.5 ppm in some of the more extensively flooded lakes (Figure 5.5.4B-5).
5.5.4.4.2
Current Fish Mercury Concentrations in Reference Lakes
For an assessment of current fish mercury concentrations of on-system waterbodies in the ROI it is
important to establish a benchmark of “natural” concentrations against which a comparison can be made.
Off-system lakes, unaffected by hydrological changes and other human impacts that may alter the local
conditions of methylmercury availability to fish, were assumed to represent natural conditions. Relatively
few off-system lakes with recent fish mercury data exist in the ROI. To obtain a broader geographical
representation of “natural background concentrations” for each of the three focal species, results for offsystem lakes from other areas were used in addition to those for Leftrook Lake, the CAMP off-system
reference lake for the CRD Region. This also included Granville Lake which is located just west of Area 3.
DECEMBER 2015
5.5-71
Granville Lake is the CAMP off-system reference lake for the Upper Churchill River Region and has a
long-term data set on fish mercury concentrations, including from recent sampling. Furthermore, to base
the estimate of background concentrations on a broad data base, and because there was no temporal
trend in the yearly means, mercury concentrations for years 2002–2014 were considered “current” and
included in the calculation of the overall mean for each species (Table 5.5.4-2).
With one exception (pike from Leftrook Lake in 2010), mercury concentrations of Walleye and pike from
the off-system Leftrook, Gauer and Assean lakes have ranged from slightly below 0.2 ppm to slightly
above 0.3 ppm since 2002, with overall means for each lake at or marginally above 0.2 ppm
(Table 5.5.4-2). Pike from Setting Lake and pike and Walleye from Granville Lake had mean mercury
concentrations between 0.32 and 0.38 ppm since 2002 (Table 5.5.4-2). Gauer Lake generally had the
lowest and Granville Lake generally had the highest mercury concentrations in pike and Walleye of all the
off-system lakes. For whitefish the pattern differed, as mean concentrations in fish from Assean Lake
were twice as high in those from Setting Lake (Table 5.5.4-2).
Granville Lake is considered unaffected by hydroelectric development (Water Regime, Section 4.3.3.2.3)
and the cause of the elevated mercury concentrations in pike, that were fairly consistently observed from
1979-1992 (Figure 5.5.4-9) remains unknown. These relatively high concentrations were all based on
commercial samples and, primarily, arithmetic means for relatively few, large fish (as was the entire
record for pike from 1970–2004). Granville Lake was excluded from the calculation of background
concentrations based on recent data from off-system lakes (Table 5.5.4-2).
DECEMBER 2015
5.5-72
Table 5.5.4-2:
Standard Mean Mercury Concentrations, Part-per-Million, for Northern Pike,
Walleye, and Lake Whitefish from Five Coordinated Aquatic Monitoring
Program Off-System Reference Lakes for Years 2002–2014
Lake
2002-07
2010
2011
2012
2013
2014
Mean
Northern Pike
Leftrook
0.277
0.392
Gauer
0.182
Granville
0.400
1
2
0.242
0.248
0.229
0.187
0.252
0.202
-
-
0.195
-
0.194
0.441
-
-
-
0.370
0.309
2
Setting
-
0.392
-
-
0.314
-
0.352
Assean
0.194
0.248
-
-
0.233
-
0.226
-
-
-
-
-
-
0.238
All lakes
*
Walleye
Leftrook
0.266
0.255
0.245
0.273
0.234
0.293
0.260
Gauer
0.193
0.246
-
-
0.180
Granville
0.229
Setting
-
Assean
All lakes
1
*
0.441
-
-
0.278
2
0.277
-
-
0.206
2
0.317
2
-
0.211
-
0.340
-
0.241
0.203
0.235
-
-
0.243
-
-
-
-
-
-
0.239
Lake Whitefish
Leftrook
0.037
4
0.026
0.026
0.021
0.027
0.031
0.024
Gauer
-
0.036
-
-
0.034
-
0.035
Granville
-
0.052
0.049
Setting
-
0.025
1
Assean
0.057
0.039
2
All lakes *
-
-
-
-
0.046
-
-
-
0.025
-
-
-
-
-
0.060
1
-
0.025
1
-
0.046
-
0.033
Note: Mean represents the standard means calculated from the raw data for all fish by species and lake across years.
1.
2.
3.
*
Arithmetic mean (relationship between fish length and mercury concentration was not significant).
Significantly different from other standard means for the lake.
Significantly different from 2011 and 2012.
Excluding Granville Lake.
DECEMBER 2015
5.5-73
0.8
CRD
flooding
Granville Lake
Pike
Walleye
Whitefish
*
0.6
*
*
*
*
*
0.4
*
*
*
*
*
*
*
*
*
* *
*
*
*
*
*
0.2
0.0
70
19
75
19
80
19
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
mercury concentration was not significant and the arithmetic mean was used. Except for 1981 and 1999, all arithmetic means were
for 10 or less fish. The stippled line indicates the 0.5 ppm Health Canada standard for retail fish.
Figure 5.5.4-9:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From Granville
Lake Lake for 1970–2014
The recent mercury concentrations observed in the three focal species from the ROI off-system lakes
listed in Table 5.5.4-2 are remarkably similar to the concentrations obtained from Area 3 off-system lakes
(which, with the exception of Granville Lake represent a different set of lakes) during years pre-dating
hydroelectric development (Table 5.5.4-1). Combined with the relatively stable mercury concentrations
observed in fish from Leftrook Lake between 1976 and 2014 (see Section 5.5.4.3.7), this indicates that
baseline mercury concentrations in the three best-studied fish species have changed little in Area 3
off-system waterbodies over the past 30 years.
DECEMBER 2015
5.5-74
5.5.4.4.3
Evolution Fish Mercury Concentrations in Relation to Hydroelectric
Development
CHURCHILL RIVER DIVERSION
This section will summarize results from Area 3 for the time course of fish mercury concentrations in
response to flooding from CRD. To establish common generalities in the response but also to document
the range in responses, results from the three reservoirs in Area 2 (Stephens Lake, Long Spruce and
Limestone forebays) were included to more fully document temporal change in mercury concentrations of
the three focal species in the entire ROI.
Table 5.5.4-3 summarizes several parameters that characterize the evolution in mercury concentrations
for Lake Whitefish, Northern Pike and Walleye from reservoirs and lakes that experienced flooding due to
hydroelectric development. The percent flooding for each lake/reservoir is indicated, as well as mercury
concentrations prior to flooding (Hg pre-flood; if available) and recorded maximum (Hg max) and
minimum (Hg min) post-flood concentrations. The number of years to reach Hg min after reaching Hg
max (return time) is also provided. To obtain a measure of the relative increase in mercury concentrations
due to flooding, an increase factor (IF) was calculated as the ratio of Hg max to Hg pre-flood. Given the
absence of pre-Project data for most of the lakes, pre-flooding mercury concentrations were mostly
estimated based on the average (weighted by sample size) concentration from three on-system lakes
with existing pre-flooding data: 0.060 ppm for whitefish, 0.298 ppm for pike, and 0.275 ppm for Walleye
(see Table 5.5.4-1). These estimates are for composite samples of fish from commercial catches.
Although pre-CRD (1975) samples for whitefish from several areas of SIL and from Cauchon Lake
indicate that samples based on individual fish may provide similar results than the commercial samples
(see Section 5.5.4.3), as documented on multiple previous occasions, mercury concentrations from
commercially caught fish, particularly pike and Walleye for a specific waterbody and year are often higher
than standard means and likely overestimate the population as a whole. However, based on current
mercury concentrations in fish from off-system lakes (Table 5.5.4-2), this difference may be small for the
estimates of Hg pre-flood used in Table 5.5.4-3. Nevertheless, the IF values presented in Table 5.5.4-3
likely represent underestimates, particularly for fish from waterbodies for which sampling started 10 or
more years after flooding and where Hg max was recorded in the first sampling year (e.g., Stephens lake,
Long Spruce forebay).
Similarly, most of the “return” times listed in Table 5.5.4-3 represent underestimates of the time it takes for
fish to return to a concentration assumed to have existed pre-flooding (i.e., Hg pre-flood) or that
represents a new baseline concentration (also referred to as “current background concentrations” as
measured from off-system lakes for 2002–2014; Table 5.5.4-2). This applies in particular to those
waterbodies and species for which the year Hg min was recorded represented the last year of sampling
(e.g., Walleye in Notigi Lake) and the concentrations were (still) substantially higher than current
background. Assuming that the overall mean (0.24 ppm for pike and Walleye) for the four off-system
lakes is a reasonable approximation of current background concentrations, Hg min was still significantly
higher for pike and Walleye from all lakes on the CRD route, except for Walleye from SIL Area 4.
Conversely, concentrations representing Hg min for pike and Walleye from the three reservoirs on the
lower Nelson River in Area 2 (see Table 5.5.4-3) were similar to or even significantly lower (e.g., pike and
DECEMBER 2015
5.5-75
Walleye from Limestone forebay) than current background concentrations. Such a difference between
ROI Areas 2 and 3 was not observed for whitefish. For this species, Hg min was mostly higher than
background in both areas (0.033 ppm; see Table 5.5.4-2), except for whitefish from SIL Area 6, and
Stephens and Issett lakes (Table 5.5.4-3).
Irrespective of the limitations of the available data, the evidence from the many flooded lakes and
reservoirs in the ROI clearly shows that inundation of soils and vegetation resulted in substantially
elevated fish mercury concentrations compared to those existing pre-flood or for waterbodies not affected
by hydroelectric development. The underlying causes for this phenomenon have been extensively studied
(particularly within the ROI) and are well understood. Bodaly and Hecky (1979) were the first to attribute
the increase in fish mercury concentrations after flooding to a greater supply of inorganic mercury from
the leaching of humic rich soils and an increase in mercury bioavailability due to bacterial mercury
methylation. This conclusion was based mainly on the mercury results for whitefish from Southern Indian
Lake (SIL) and Issett Lake, along with accompanying limnological research. These authors further
postulated that mercury concentrations would be highest in top-level predators such as Northern Pike and
Walleye due to the biomagnification of methylmercury through the food chain and that the increase in fish
mercury concentrations would be in some proportion to the enhanced supply and increased methylation
rate of mercury. These hypotheses have been confirmed and the knowledge base expanded over the last
three decades (Bodaly et al. 1984a b, 1997, 2007; Hecky et al. 1991; Lucotte et al. 1999;
Schetagne et al. 2003). This includes studies on experimental reservoirs that have greatly enhanced the
understanding of the processes affecting rates and persistence of mercury methylation and the
bioavailability of methylmercury (Kelly et al. 1997; St Louis et al. 2004, Bodaly et al. 2004;
Hall et al. 2005). Predictive models also have been developed to quantify expected mercury levels in fish
following flooding (e.g., Johnston et al. 1991; Harris and Hutchinson 2009).
The results presented in Table 5.5.4-3 differ to some degree from similar data previously published in
Bodaly et al. (2007) for several reasons:
•
Additional data on fish mercury concentrations have been obtained from previously unavailable
sources and in a few cases this has changed the value of Hg max and the time to reach Hg max.
•
For the current assessment, standard means were only used in those cases where the regression
equation for the relationship between mercury concentration and fish length was significant. If this
was not the case, the arithmetic mean was used. Also, if (arithmetic) means from two adjacent years
represented the highest and second highest concentrations for a species in a particular lake and were
based on small sample sizes, data from both years were combined to calculate a standard mean
(e.g., Walleye from Notigi Lake; pike and Walleye from Osik Lake).
•
The return times listed in Table 5.5.4-3 were estimated based on the changes in fish mercury
concentrations within each lake. In contrast, Bodaly et al. (2007) assigned return times for fish from
each lake by using the first year for which the lower limit of the 95% confidence interval of an
observed mean concentration overlapped with the upper limit of the 95% confidence interval for the
mean of a large number (> 60) of “pristine” lakes. However, these lakes included waterbodies that
were impacted by human activities (e.g., Saskatchewan River), had relatively high mercury
concentrations in at least some resident fish species for unknown reasons (e.g., LeClair, Drunken,
and Granville lakes) and/or the mean concentrations for a particular year was based on few, large
DECEMBER 2015
5.5-76
fish. The resulting “background mean concentrations” were quite high (approximately 0.41 ppm for
pike and Walleye) and were associated with relatively large confidence intervals.
•
Many of the estimates of lake areas prior to and post flooding, and the resulting percentage of
flooding differed between the current data set and those previously published
(e.g., Newbury et al. 1984, Bodaly et al. 2007). Pre- and post-flooding areas, particularly for Area 3,
have recently been re-calculated (see Appendix 5.5.4C) and for some waterbodies the percentage of
flooding as calculated in Section 5.5.1.4 is substantially smaller or larger than the existing estimates.
This obviously will affect any analysis relating Hg max to Flood (%). Except for Issett Lake, for which
estimates of the percentage of flooding increased from 455% to 2,467% (Table 5.5.4-3), all other
waterbodies were included with their recent area estimates and percentage of flooding in the
respective analysis (see Figure 5.5.4-10 and Table 5.5.4-3).
The current assessment indicates that maximum mercury concentrations in pike from waterbodies in the
ROI ranged from 0.35 to 1.95 ppm, corresponding to IFs of 1.1-6.5 (Table 5.5.4-3). Considering the only
few available samples based on relatively few fish for Opachuanau Lake for 1978–1988, the Hg max of
0.35 ppm likely does not represent the actual Hg max of the pike population. Maximum concentrations in
pike from both regions of SIL were 1.5 times to more than two times higher than those for fish from the
Limestone forebay, which, according to the most recent calculations was flooded to a similar degree
(7-8%). Despite such large differences in fish mercury concentrations for similar amounts of flooding
between some waterbodies, a significant linear relationship existed between (log) Hg max and (log)
Flood(%), with percent flooding explaining almost half of the variability in Hg max (Figure 5.5.4-10). For
the 10 waterbodies with sufficient data to allow an estimate, return times ranged from 8 (Limestone
forebay) to 30 (SIL, Area 4) years.
Maximum mercury concentrations in Walleye, excluding Opachuanau Lake, ranged from 0.54 to
2.38 ppm, corresponding to IFs of 2.0–8.7 (Table 5.5.4-3). Unlike for pike, Hg max for Walleye from both
regions of SIL were similar than those for their conspecifics from the Limestone forebay. There was a
significant linear relationship between (log) Hg max and (log) Flood(%), the latter explaining 64% of the
variability in Hg max (Figure 5.5.4-10). For the 10 waterbodies with sufficient data to allow an estimate,
return times ranged from 13 (Limestone forebay) to 30 (SIL, Area 4) years.
The number of waterbodies with sufficient data to estimate parameters that characterize the response of
mercury concentrations to lake flooding was smaller for whitefish than for the two piscivorous species
(Table 5.5.4-3). Excluding Isset Lake (see Section 5.5.4.3.2), maximum mercury concentrations in
whitefish ranged from 0.14 to 0.27 ppm. However, the corresponding IFs of 1.7 to 4.3 were similar or
even higher (e.g., Long Spruce forebay, SIL) compared to pike and Walleye from lakes with little or
moderately flooding (i.e., < 100%), whereas the differences in IF between the benthivore and the two
piscivores were larger for the extensively flooded lakes (Table 5.5.4-3). Similar to pike, Hg max and,
particularly the IF for whitefish from both regions of SIL were substantially higher than those for their
conspecifics from the Limestone forebay. However, unlike pike and Walleye, the relationship between Hg
max and percentage flooding was not significant for whitefish. For the nine waterbodies with sufficient
data to allow an estimate, return times ranged from 0 (i.e. Hg max was never significantly different from
any of the following standard means) for the Limestone forebay to 30 years for Threepoint Lake
(Table 5.5.4-3).
DECEMBER 2015
5.5-77
Table 5.5.4-3:
Average mercury concentration prior to flooding (Hg pre-flood), maximum post-Churchill River Diversion mercury concentration (Hg Max), the number of years to reach Hg Max after the end of flooding,
minimum mercury concentration post-Churchill River Diversion (Hg Min), the year Hg Min was observed, the increase factor, and the return time for Lake Whitefish, Northern Pike, and Walleye from fifteen
Area 3 lakes flooded by Churchill River Diversion and three reservoirs in Area 2
Lake / Reservoir
SIL, Area 6
Flood (%)*
7
Species
Hg pre-flood
(ppm)
Hg Max (ppm)
Years to Hg Max
Increase
Factor**
Hg Min (ppm)
Year of Hg Min
(post Hg max)
Return time (years)
Increase post Hg Min
Whitefish
0.06
0.238
4 (79)
4.0
0.026
2005 (26)
26 (79-05)
no
Pike
0.29
1.095
9 (84)
3.8
0.317
2005 (21)
24 (82-05)
yes
Walleye
0.23
0.803
3 (78)
3.5
0.334
2005 (27)
27 (78-05)
yes
n/a
n/a
Whitefish
SIL, Area 4
7
Rat
Notigi
Threepoint
Wuskwatim
Footprint
Osik
Apussigamasi
Karsakuwigamak
Mynarski, West
Mynarski, East
Pemichigamau
DECEMBER 2015
2467
158
324
44
50
87
55
69
105
38
37
118
0.218
3 (78)
4.1
0.067
0.371
1
1986
1
2010
1
Pike
-
0.704
9 (84)
2.4
Walleye
-
0.607
5 (80)
2.6
0.193
3 (78)
2.2
0.023
2005 (27)
27 (78-05)
yes
9 (83)
2.8
0.361
2005 (22)
23 (82-05)
no
11
11
Whitefish
Issett
0.053
1
0.146
Pike
-
Walleye
-
12
0.324
12
0.846
2013
10
(33)
<30
no
30 (80-10)
n/a
1.520
2
4 (78)
5.5
0.342
2005 (27)
20 (78-98)
no
10 (84)
4.1
0.031
1994 (10)
10 (84-94)
yes
4 (78)
5.7
0.475
2005 (25)
21 (78-99)
no
Whitefish
-
0.250
3
Pike
-
1.688
4
Walleye
-
2.380
4 (78)
8.7
0.409
2005 (27)
26 (78-05)
yes
Whitefish
-
0.267
11 (85)
4.3
0.066
2001 (16)
18 (81-99)
yes
Pike
-
1.948
6 (80)
6.5
0.591
2002 (22)
21 (80-01)
no
Walleye
-
1.857
5
Whitefish
-
0.251
6
Pike
-
1.758
7 (83)
5.9
0.377
2005 (22)
22 (83-05)
yes
Walleye
-
1.654
7 (83)
6.0
0.345
2005 (22)
19 (83-02)
yes
Whitefish
0.08
0.248
5 (81)
3.1
0.049
2005 (24)
24 (81-05)
yes
Pike
7 (81)
6.7
0.452
5 (81)
4.1
0.054
2007
10
(26)
18 (81-99)
n/a
2014
10
(33)
30 (81-11)
n/a
-
1.418
8 (84)
4.8
0.305
2005 (21)
21 (84-05)
yes
Walleye
0.34
0.944
4 (80)
2.8
0.242
1996 (16)
17 (79-96)
yes
Whitefish
-
0.225
4 (80)
3.6
-
-
-
n/a
Pike
-
1.479
8 (84)
5.0
-
-
-
n/a
Walleye
-
1.229
7 (83)
4.5
-
-
-
n/a
7 (83)
4.9
-
-
-
n/a
7 (83)
3.3
-
-
-
n/a
Pike
-
1.457
7
Walleye
-
0.917
8
Pike
-
1.177
8 (84)
3.9
-
-
-
n/a
Walleye
-
1.528
8 (84)
5.6
-
-
-
n/a
Whitefish
-
0.216
- # (84)
3.5
-
-
-
n/a
Pike
-
1.405
- # (84)
4.7
-
-
-
n/a
Walleye
-
1.972
- # (84)
7.2
-
-
-
n/a
Pike
-
0.805
10 (84)
2.9
-
-
-
n/a
Walleye
-
0.922
10 (84)
3.4
-
-
-
n/a
0.567
9
≤7 (81)
2.1
-
-
-
n/a
- # (85)
4.0
-
-
-
n/a
- # (85)
5.3
-
-
-
n/a
Walleye
-
Pike
-
1.191
9
Walleye
-
1.471
9
5.5-78
Table 5.5.4-3:
Average mercury concentration prior to flooding (Hg pre-flood), maximum post-Churchill River Diversion mercury concentration (Hg Max), the number of years to reach Hg Max after the end of flooding,
minimum mercury concentration post-Churchill River Diversion (Hg Min), the year Hg Min was observed, the increase factor, and the return time for Lake Whitefish, Northern Pike, and Walleye from fifteen
Area 3 lakes flooded by Churchill River Diversion and three reservoirs in Area 2
Lake / Reservoir
Flood (%)*
Moss
52
Opachuanau
McLeod
Stephens
7
14
226
Species
Pike
Limestone
92
8
Hg Max (ppm)
Years to Hg Max
Increase
Factor**
Hg Min (ppm)
Year of Hg Min
(post Hg max)
Return time (years)
Increase post Hg Min
-
0.793
- # (85)
2.7
-
-
-
n/a
Walleye
-
1.075
≤7 (82)
3.9
-
-
-
n/a
Pike
-
0.349
- # (81)
1.1
-
-
-
n/a
Walleye
-
0.303
- # (81)
1.1
-
-
-
n/a
Pike
0.559
- # (83)
1.9
-
-
-
n/a
Walleye
0.540
- # (85)
2.0
-
-
-
n/a
0.191
Whitefish
-
Pike
-
Walleye
Long Spruce
Hg pre-flood
(ppm)
-
9
<14 (84)
3.2
0.029
2005 (21)
22 (83–05)
yes
1.045
9
≤13 (83)
3.5
0.180
2005 (≥22)
≥22 (83–05)
yes
1.890
9
≤11 (81)
6.9
0.204
2005 (≥24)
≥24 (81–05)
yes
≤8 (85)
2.9
≤8 (85)
2.3
Whitefish
-
0.175
9
Pike
-
0.697
9
1993 (≥8 )
≥7 (85–92)
n/a
0.231
10
2003 (≥18)
≥18 (85–03)
n/a
0.239
10
0.073
Walleye
-
0.641
9 (86)
2.3
2003 (≥17)
≥17 (86–03)
n/a
Whitefish
0.082
0.136
2 (91)
1.7
0.079
2003 (≥12)
0
yes
Pike
0.324
0.453
5 (94)
1.4
0.188
2001 ( 7)
8 (93–01)
yes
-
0.639
5 (94)
2.3
0.184
2005 (11)
13 (92–05)
yes
Walleye
Notes:
parts-per-million (ppm)
A significant increase in mercury concentrations after reaching Hg Min is indicated (Increase post Hg Min).
The return time is the Number of years from the earliest year mercury concentrations were not significantly different from Hg Max to the earliest year concentrations were statistically similar to Hg Min.
* Flood (%) = (flooded area/pre-flooding area) x 100.
** Ratio of Hg Max to Hg pre-flood; IF for lakes without pre-CRD data was estimated as the weighted average of the means for Opachuanau, SIL Area 6, and Wuskwatim lakes (Table 5.5.4-1): 0.062 ppm for Lake Whitefish, 0.298 ppm for Northern Pike, and 0.275 ppm for Walleye.
# = Insufficient data to assign.
1. No data exist for years 1989-2009; the results for 1986 or 2010 likely don’t represent Hg min.
2. Arithmetic mean is for 5 fish; next highest Hg max is a standard mean of 1.13 ppm for 1986.
3. An arithmetic mean of 0.396 ppm for 5 large (mean fork length = 439 mm) for 1978 exist.
4. Standard mean; a mean of 2.14 ppm exists for 5 commercial samples in 1977.
5. Mean is the standard mean for 4 fish from 1980 and 29 fish from 1981.
6. Mean is the standard mean for 5 fish from 1980 and 16 fish from 1981.
7. Mean is the arithmetic mean for 5 fish from 1982 and 5 fish from 1983.
8. Mean is the arithmetic mean for 6 fish from 1982 and 12 fish from 1983.
9. When measured for the first time.
10. Last year of sampling.
11. Only one sample for 2008 is available.
12. Likely represents an overestimate of the actual population means at the time (see Section 5.5.4.3.2)
DECEMBER 2015
5.5-79
3
Muscle Mercury (ppm)
Northern Pike
2
Not
3-Pt
Rat
FPr
Osik
Wus
Kar
Pemi
Apus
SIL6
Stp
1
My-W
Moss
SIL4
LSp
MCL
0.5
LSt
Opach
0.3
log (Hg) = -0.461 + 0.279 (log Flood%) ; r2=0.49
0.2
5
10
20
50
100
200
300
3
Walleye
Rat
2
Kar
Stp
Not
3-Pt
Apus
Pemi
FPr
Moss
1
My-W
Wus
Osik
SIL6
SIL4
LSp
LSt
My-E
MCL
0.5
0.3
Opach
log (Hg) = -0.605 + 0.368 (log Flood%) ; r2=0.64
0.2
5
10
20
50
100
200
300
Flooding (%)
Regression equation (log Hg) = a + b (log Flood%). The Best-fit regression and the corresponding regression lines are shown.
Figure 5.5.4-10:
Maximum Observed Mercury Concentration in Northern Pike and Walleye From
Lakes and Reservoirs in Areas 2 and 3
DECEMBER 2015
5.5-80
Based on the large amount of data on fish mercury concentrations from almost 20 lakes spanning more
than four decades, a generalized timeline for the rise and fall of concentrations after lake flooding can be
obtained for the ROI (Figure 5.5.4-11).
2.0
~10 - >30 years
1.5
Start of
flooding
1.0
0.5
3-9 years
0.0
0
5
10
15
20
25
30
35
40
45
Time (years)
The time to reach maximum concentrations (blue font) and the return time to pre-flood or current background concentrations (green
font) is indicated.
Figure 5.5.4-11:
Generalized Timeline (Red Line) of Changes in Fish Mercury Concentrations
Based on Results From Reservoirs and Flooded Lakes Due to Hydroelectric
Development in the Region Of Interest
Figure 5.5.4-11 shows that fish mercury concentrations increased relatively rapidly after flooding to reach
a very transient maximum, after which concentrations declined over an extended period of time, relatively
quickly at first, more gradually later. Maximum concentrations in piscivorous species from the more
extensively flooded lakes reached approximately 2 ppm, whereas maxima in large bodied species of
lower trophic levels generally did not exceed 0.5 ppm and remained below 0.3 ppm in Lake Whitefish.
Maximum concentrations were usually reached within 3–9 years post-flood in pike, Walleye, and
whitefish, with the latter species often being at the lower end of the range. The estimated time to reach
minimum concentrations after peaking was quite variable between lakes and species, spanning a range
from slightly less than 10 years to 30 years. In almost all cases minima were either measured in the last
year that sampling was conducted in a given waterbody or occurred in 2005 and were followed by
significantly higher concentrations in subsequent years.
DECEMBER 2015
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DOWNSTREAM EFFECTS OF HYDROELECTRIC DEVELOPMENT ON FISH MERCURY
CONCENTRATIONS IN AREA 3
Increases in fish mercury concentrations in downstream environments have been attributed to the export
of methylmercury from reservoirs in Manitoba (Johnson et al. 1991; Bodaly et al. 2007), Québec
(Schetagne et al. 2003) and Newfoundland and Labrador (Harris and Hutchinson 2007). It is difficult to
quantify the effect of downstream transport on fish mercury concentrations because of the paucity of
similar assessments in the literature and the potential for site and species specificity of the downstream
effect (Bodaly et al. 2007; Harris and Hutchinson 2007). There is little direct evidence for a downstream
effect of reservoir flooding on fish mercury concentrations within Area 3. Large waterbodies on a diversion
route (such as CRD) greatly reduce further export downstream because they act as methylmercury sinks
via sedimentation of suspended particular matter and local predation of fish food organisms with elevated
mercury concentrations (Schetagne and Verdon 1999a; Schetagne et al. 2003). Thus, the magnification
of a local increase in fish mercury concentration from a flooded lake located upstream (i.e., a downstream
effect) should conceptually only happen for pairs of adjacent lakes on the CRD route if at all. However, no
empirical studies exist that would allow discrimination of any upstream contributions to the environmental
methylmercury pool and its subsequent uptake through the food chain into the focal fish species in a
downstream lake or reservoir.
The general pattern of rise and fall in fish mercury concentrations is similar for all flooded lakes and it is
difficult to find a reflection of some of the detailed temporal changes in concentrations from any of the
lakes in the immediate downstream lake. These patterns (or lack thereof) do not exclude the possibility of
a downstream effect, but if one existed, the effect was too small to be detected.
DECEMBER 2015
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5.5.5
Area 4: Missi Falls Control Structure to the
Churchill River Estuary
The Churchill River downstream of SIL has experienced substantial alterations in its hydrological regime
as a result of CRD. With the completion of the Missi Falls CS and the South Bay diversion out of SIL in
the fall of 1976, most of the flow of the Churchill River was diverted into the Nelson River basin.
3
According to Section 4.3.3.3.3 the diversion reduced Churchill River discharge by an average of 780 m ,
representing approximately 79% of the annual mean natural flow at Missi Falls CS. In addition to changes
in flows, there have been variations in the timing of peak flows. Pre-CRD, mean monthly flows peaked in
July at the outlet of Fidler Lake and in August at Red Head Rapids. Post-CRD, mean monthly flows are
shown to peak during June at the outlet of Fidler Lake and at Red Head Rapids (see Section 4.3.3.3.3).
The first peak at Red Head Rapids is likely due to the influence of inputs from major tributaries (e.g., Little
Churchill River and Little Beaver River).
Churchill River flows have also fluctuated substantially in response to natural causes (e.g., high/low runoff
and/or high/low precipitation in the drainage basin) and enhanced by Hydro regulation (e.g., reduced
discharge at the Notigi CS). As a result, the Churchill River discharge has fluctuated widely since 1978
(first year of records). Recent flood events, where post-CRD 95%ile flows at Missi Falls have been
exceeded for a period of more than two weeks, happened during July to November 2005, August 2006,
July to August 2009, and August to September 2011 (based on data introduced in Section 4.3.3.3).
Reductions in flow and water level have resulted in an increase in the amount of non-wetted river
channel. As elaborated in more detail in Erosion and Sedimentation, Section 4.4.2.5, channel width has
2
been reduced by approximately 30% and an area of about 203.6 km has been dewatered between Missi
Falls CS and Mosquito Point.
In October 1999, as part of the Manitoba Hydro and the Town of Churchill the Lower Churchill River
Water Level Enhancement Weir Project, a weir (“the Churchill Weir”) was constructed across the Churchill
River just upstream of Mosquito Point (see Section 4.3.3.3.3). The river was deepened by increasing the
water level by approximately 2.0 m along a 10 km reach between the weir and the Town. Construction of
the weir and ancillary components was carried out to improve boating, provide access to a source of
drinking water and increase the amount and productivity of fish habitat, and therefore fish, in this reach of
the river.
5.5.5.1
Mercury concentrations in mainly Northern Pike, Walleye, Lake Whitefish, and Lake Trout (Salvelinus
namaycush) from commercial catches from 13 Area 4 waterbodies between 1970–1972 were first
compiled by Derksen (1978a, b, 1979) and McGregor (1980). Commercial samples up to 1981–1983 from
Ashley, Dysart, Holmes, Cygnet, Limestone, Northern Indian, Partridge Breast, Thornsteinson, and Wood
lakes and the Churchill River mouth were reported by Rannie and Punter (1987) as part of a data
compilation funded by the Canada-Manitoba Agreement on the Study and Monitoring of Mercury in the
Churchill River Diversion (see Section 5.5.1.2). As part of the Agreement, mercury levels were also
DECEMBER 2015
5.5-83
measured in individual fish from survey samples conducted from 1978–1983 at selected lakes, including
Northern Indian and Partridge Breast lakes (data summarized across all sampling years in Rannie and
Punter 1987). Data from these two lakes were used to test predictive models relating reservoir flooding to
fish mercury concentrations developed by Johnston et al. (1991).
Mercury concentrations (including standard means) in pike and Walleye from Waskaiowaka and
Limestone lakes from 1978–1982 were reported in Green (1986) as part of a summary and statistical
analysis of fish mercury data collected under the Canada-Manitoba Agreement for 1983–1985 that also
included a compilation of available data for lakes in the Churchill and Nelson River drainages not flooded
by CRD.
Fish mercury concentrations were collected as part of the environmental assessment for the Churchill
River weir (Manitoba Hydro and the Town of Churchill 1997). To address concerns associated with a
potential for increases in fish mercury levels in response to re-watering and flooding of terrestrial habitat
resulting from the project, baseline mercury data was collected annually from 1993 to 1996 (Remnant and
Bernhardt 1994; Remnant 1995; Remnant and Kitch 1996; Fazakas and Remnant 1997), and compared
to post-project data collected from 1999 to 2013 (Bernhardt 2000, 2001, 2002, 2003; Bernhardt and Holm
2003, 2007; Bernhardt and Pisiak 2006; Bernhardt and Caskey 2009; Hertam et al. 2014 ).
Whitefish, pike, and Walleye from Caldwell, Christie, Kiask, Limestone, Pelletier, Recluse, Thomas, and
Waskaiowaka lakes were analyzed for mercury in 2005 as part of the Adverse Effects Agreement for the
Keeyask Generation Project and detailed results have been reported in the Environmental Impact
Statement (EIS) (KHLP 2012).
Fish mercury concentrations continue to be monitored in Northern Indian Lake (NIL) and the Churchill
River at its confluence with the Little Churchill River and upstream of the Churchill Weir on a three-year
rotational basis under CAMP. Results for the 2010 sampling at NIL and the Churchill River/Little Churchill
River are presented in CAMP (2014).
5.5.5.2
The current assessment is based on the updated analysis of all fish mercury data available for Area 4
from 1970 to 2014. Mercury concentrations for approximately 2,400 fish of 11 species have been
collected in Area 4 (Table 5.5.1-1), representing 4.5% of all mercury data for individual fish in the ROI. In
addition, 67 analyses of composite, commercial fish samples exist for Area 4 that can be associated with
a particular year (i.e., not including data presented in Rannie and Punter 1987; see Section 5.5.5.3).
These commercial data were used in instances where no data for individual fish were available. In these
cases, some of the published yearly means were recalculated for years with multiple composite samples
that were only reported separately. The vast majority (92%) of all individual fish mercury data collected in
Area 4 are for Lake Whitefish (24.7%), Northern Pike (38.9%), and Walleye (28.4%). All of the sites
sampled for fish mercury in Area 4 are shown in Map 5.5.5-1.
Two focal waterbodies located along the lower Churchill River were selected for detailed presentation in
the following discussion. Northern Indian Lake and the Churchill River experienced hydrological changes
related to hydroelectric development, notably a reduction in flows due to diversion of the Churchill River at
DECEMBER 2015
5.5-84
SIL, and both have fish mercury data with relatively good sample size and collection frequency to allow
conclusions on the evolution of fish mercury concentrations over an extended time period. Fish mercury
data for the Churchill River are available for three locations: the confluence of the Little Churchill River,
upstream of the Churchill Weir, and the river mouth (Map 5.5.5-1), with the latter two sites having
extensive data sets from two largely separate time periods.
DECEMBER 2015
5.5-85
Scale: 1:13,000,000
Created By: cparker - B Size Landscape STD - MAR 2015
Churchill
Churchill River Weir
Assessment
HUDSON
BAY
Legend
Focal Waterbody
Infrastructure
Control Structure
Ch
ur
c
hi
ll R
ive
r
Ashley
Lake
RCEA
Area 4
Dysart
Lake
Hudson Bay
Churchill
Little
Churchill
River
Wood Lake
Partridge
Breast Lake
Missi
Falls
Control
Structure
Northern
Indian
Lake
Thompson
Thorsteinson
Lake
Billard
Lake
Holmes
Lake
Thomas
Lake
Christie
Lake
Kiask
Lake
Campbell
Lake
Caldwell
Lake
Pelletier
Lake
Recluse
Lake
DATA SOURCE:
Province of Manitoba, Government of Canada and Manitoba Hydro.
Cygnet
Lake
Bissett
Lake
CREATED BY:
COORDINATE SYSTEM:
0
Waskaiowaka
Lake
Limestone
Lake
10
20 Kilometres
DATE CREATED:
REVISION DATE:
28-OCT-15
08-DEC-15
VERSION NO:
QA/QC:
1.0
0
10
20 Miles
Waterbodies with
Information on
Mercury in Fish
RCEA Area 4
Map 5.5.5-1
5.5.5.3
Pre-CRD Baseline Mercury Concentrations
Area 4 contains a relative large number (compared to the total number of waterbodies with fish mercury
data) of off- and on-system waterbodies with fish mercury data from composite commercial samples that
predate CRD (i.e., 1976). Although it is often difficult to precisely assign some of the information
presented in Derksen (1978 a, b) and Derksen (1979) to a specific year over the period 1970–1972, a
comparison of location-specific sample sizes and mercury concentrations among the three publications
by Derksen in combination with information provided in Rannie and Punter (1987) and McGregor (1980)
allows such an assignment with considerable confidence (Table 5.5.5-1). Only the several samples that
exist for Northern Pike and Walleye from the mouth of the Churchill River for 1973–1976
(Rannie and Punter 1987) cannot be dated to a specific year because the authors only provide an
average concentration and range for the entire sampling period on record.
Based on the results presented in Table 5.5.5-1, pre-CRD mercury concentrations were similar between
on-system and off-system waterbodies with means ranging from 0.07–0.16 ppm in Lake Whitefish,
0.27-0.51 ppm in Northern Pike, and 0.14–0.37 ppm in Walleye. The range of mercury concentrations in
pike and Walleye from off-system lakes encompassed the range of concentrations in their conspecifics
from on-system waterbodies. With a few exceptions (e.g., pike from Limestone Lake, whitefish from NIL)
concentrations are also similar to those for fish sampled commercially from Area 3 lakes during years
pre-dating CRD (Table 5.5.4-1). As noted in Section 5.5.4.3 (Area 3), the composite nature of commercial
samples (see Section 5.5.1.4), and their typically small sample size and unknown length of the fish
included in the sample precludes statistical comparisons among commercial samples. Therefore, the
conclusion of equality in fish mercury concentrations between on-system and off-system waterbodies is
weak for comparisons of individual lakes, and is based on the weight of evidence for the entire dataset.
It should also be noted that Area 4 is the only area within the ROI that has information on mercury
concentrations in Lake Trout for pre-and post-CRD years. Derksen (1978b) reported a concentration of
0.20 ppm in trout from both Buckland Lake in 1970 and Kiask Lake sometime from 1970–1972 (also see
Derksen 1979). For post-CRD concentrations in trout from Kiask Lake see below.
DECEMBER 2015
5.5-87
Table 5.5.5-1:
Mean (range) Mercury Concentrations, Part-per-Million, for Northern Pike,
Walleye, and Lake Whitefish from On-System and Off-System Waterbodies in
Area 4 for Years Predating Churchill River Diversion (1970–1972)
Off-system
Location
n
Mean
On-system
Location
Range
n
Mean
Range
8
0.42
0.12–0.89
Northern Pike
Bissett Lake
1
0.27
-
Churchill River*
Limestone Lake
3
0.51
0.31–0.69
Waskaiowaka L.
19
0.37
0.13–0.66
Walleye
Caldwell Lake
2
0.37
0.33–0.41
Billard Lake
1
0.33
-
Christie Lake
3
0.29
0.22–0.39
Churchill River*
11
0.23
0.09–0.28
Campbell Lake
1
0.29
-
Northern Indian L.
2
0.36
1
0.28–0.43
Holmes Lake
3
0.14
0.12–0.16
Limestone Lake
8
0.34
0.24–0.42
Waskaiowaka L.
8
0.21
0.07–0.34
Lake Whitefish
Buckland Lake
1
0.07
-
Billard Lake
1
0.08
-
Campbell Lake
1
0.11
-
Churchill River*
2
0.08
0.04–0.12
Wood Lake
2
0.06
0.04–0.09
Fidler Lake
1
0.10
-
Northern Indian L.
1
0.16
-
Note: All data are for fish from composite samples of commercial catches; n indicates the number of samples. Data sources:
Derksen (1978a,b, 1979); McGregor (1980); Rannie and Punter (1987).
* Near Churchill (Derksen 1978b) or near Hudson Bay (Derksen 1979).
1. From Derksen (1978b, 1979); McGregor (1980) lists one sample each for 1970 and 1972 with concentrations of 0.28 ppm.
5.5.5.4
This section will provide a detailed description of the time series of fish mercury observed for each focal
waterbody. Subsequent sections will compare mercury concentrations to standards and guidelines,
between on-system and off-system waterbodies, and will discuss the evolution of fish mercury
concentrations in Area 4 with respect to hydroelectric development.
DECEMBER 2015
5.5-88
5.5.5.4.1
Northern Indian Lake
Northern Indian Lake located on the Churchill River approximately 43 km downstream of the Missi Falls
CS experienced a reduction in average water surface elevation of approximately 2.3 m as a result of
CRD.
Mercury data based on individual pike and Walleye are available for seven years between 1978 and
2013. In addition to the sometimes large gaps in the period of record, the samples collected from
1978-1996 were often small and the relationship between fish length and mercury concentration was not
significant, precluding the calculation of standard means (Figure 5.5.5-1).
0.8
Start of flow changes
due to CRD
Pike
Walleye
Whitefish
0.6
*
0.4
*
n=5
n=6
*
n=5
*
*
n=6
n=5
n=5
*
*
n=5
0.2
0.0
70
19
75
19
80
19
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
mercury concentration was not significant and the arithmetic mean was use; n represents sample size. Stippled lines indicate the
0.5 ppm Health Canada standard for retail fish.
Figure 5.5.5-1:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From Northern
Indian Lake for 1971–2013
Considering these shortcomings in the available record, there is no indication of a temporal trend or
consistent changes in concentrations that could be associated with hydroelectric development. Although
no data are available from NIL for years close to 2005, the recent (2010) relatively high mercury
concentrations of 0.53 ppm in pike and Walleye are consistent with increases in concentrations observed
DECEMBER 2015
5.5-89
for other on-system lakes in the ROI in years following of 2005. The decrease in concentrations in pike
and walleye from NIL between 2010 and 2013 was significant for both species.
5.5.5.4.2
Churchill River
The Churchill River runs approximately 450 km downstream from the Missi Falls CS to its mouth at the
town of Churchill. Fish mercury data mainly exist for two locations located within the most downstream
15 km of the river, with some very recent (CAMP) data coming from the confluence with the Little
Churchill River approximately 200 km upstream of the mouth. As described above, the river flow just
downstream of Missi Falls CS has been reduced by almost 80% as a result of CRD. Farther downstream,
it is estimated that the percentage of flow at Red Head Rapids originating from Missi Falls was 46% with
CRD and would have been 83% without CRD.
CHURCHILL RIVER MOUTH
Mercury concentrations in pike and Walleye from the mouth of the Churchill River are available for the
years 1970–1998, however, commercial data from 1973–1976 cannot be assigned to a particular year
(see Section 5.5.5.3) and were not considered in Figure 5.5.5-2. Similar to NIL, most of the survey
samples are associated with small numbers of fish and the relationship between fish length and mercury
concentration was not significant, precluding the calculation of standard means (Figure 5.5.5-2).
The time series of mercury concentration in fish from the mouth of the Churchill River is characterized by
a high interannual variability without a consistent trend, and considerable synchrony in mean
concentrations between pike and Walleye from 1982 onwards (Figure 5.5.5-2). Concentrations in the two
piscivores range from 0.02 ppm (the lowest mean recorded for both species anywhere in the ROI) to 0.64
ppm and 0.34 ppm, respectively. The frequent occurrence of mercury concentrations below 0.1 ppm is
very unusual for pike and Walleye in the ROI or anywhere in their natural range (Bodaly et al. 1993;
Garcia and Carignan 2000; Schetagne et al 2003), particularly when considering that these were
relatively large fish (mean fork length 575–614 mm for pike, 331–476 mm for Walleye). One possible
explanation for these low concentrations is that pike and Walleye captured in late summer or fall at the
mouth of the river near the Hudson Bay (Figure 5.5.5-1) have been feeding mainly and for a prolonged
period of time on food that has sequestered mercury in the marine environment. The marine species
Capelin (Mallotus villotus) was sampled together with several freshwater fish at the river mouth in 1970,
and at 0.04 ppm had the lowest mercury concentration of all species (together with one sample for Lake
Whitefish; Derksen 1978a, b, 1979). Marine fish generally have lower mercury concentrations than
similar-sized freshwater species (e.g., Atwell et al. 1998; Stern and MacDonald 2005). Thus, pike and
Walleye feeding mainly on Capelin or other marine species would biomagnify mercury at a lower rate
than when feeding on more typical prey fish, resulting in lower mercury concentrations. The yearly
synchronous fluctuations in concentrations for both predatory species may be the result of changes in the
distribution of marine prey species and their overlap with pike and Walleye foraging habitat. In those
years when marine prey fish and predator foraging habitat distributions don’t or only marginally overlap,
pike and Walleye would feed mainly on freshwater species and biomagnify mercury more rapidly.
However, because mercury concentrations in the relatively large fish analyzed for mercury change
relatively slowly over time (see page below), the sometimes pronounced and significant differences in
DECEMBER 2015
5.5-90
mercury concentrations of pike and Walleye between consecutive years (e.g., 1983–1984) must have an
additional or alternative explanation.
0.8
due to CRD
Completion
of weir
Pike
Walleye
*
Churchill R., Mouth
n=5
0.6
0.4
n=5
*
*
1.11
*
0.2
*
n=6
n=5
*n=5
n=5
*
n=5
*
*
n=5
*
n=5
n=5
*
0.0
70
19
75
19
80
19
n=6
n=6
* n=8
*n=6
85
19
n=5
*
*
90
19
n=6
*
*
n=5
95
19
00
20
05
20
10
20
Year
mean was used. A number denotes an upper CL not shown as a bar; n represents sample size. The stippled line indicate the
0.5 ppm Health Canada standard for retail fish. Means without CL prior to 1980 are from commercial samples.
Figure 5.5.5-2:
Concentrations of Northern Pike and Walleye From the Churchill River Mouth
for 1970–1998
CHURCHILL RIVER UPSTREAM OF THE CHURCHILL WEIR
Mercury concentrations in Lake Whitefish and Northern Pike from the Churchill River just upstream of the
weir have been regularly measured since 1994 as part of the Lower Churchill River Water Level
Enhancement Weir Project (Hertam et al. 2014). More limited data are available for Walleye in this area.
Concentrations in whitefish and pike for the relatively large samples from the weir location did not show
fluctuations similar to those observed for pike and Walleye from the mouth of the river. The standard
mean of pike for 1995 (the one common data year) was five times higher than the arithmetic mean of their
conspecifics from the river mouth, indirectly supporting the hypothesis of a temporally/spatially varying
diet of the piscivorous species sampled near the mouth (see above).
DECEMBER 2015
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Pike mercury concentrations at the Churchill Weir were highest (0.34 ppm) in 1995, but statistically similar
to the concentrations measured in the other two pre-weir years, 1994 and 1996 (Figure 5.5.5-3). Since
1995 concentrations have continuously declined, reaching a minimum of 0.22 ppm in 2005. Starting in
2001, standard means have been significantly lower than any of those in pre-weir years.
Concentrations have increased from 2005 to 2008 after which they decreased in 2013 (Figure 5.5.5-3).
The increase to 2008 was just not significant and the most recent concentration is still significantly lower
than any of those during pre-weir years. The two available samples from 2010 and 2013 for pike from the
rd
3 site on the Churchill River (near the confluence of the Little Churchill River) indirectly support a
potential pattern of a post-2005 increase and subsequent decrease in pike mercury concentrations. At
0.33 ppm, the concentration in 2010 represents a further increase from the 0.27 ppm measured for the
weir ite in 2008, and at 0.27 ppm the concentration for 2013 is quite similar to the 0.24 ppm measured at
the weir site. The increase in standard mean mercury concentrations of pike from 2005 to 2008 (i.e., nine
years after the completion of the weir) is unlikely a consequence of project-related flooding and other
explanations have to be sought.
Mercury concentrations in whitefish have fluctuated less than those in pike, ranging from 0.08 ppm in
1999 to 0.12 ppm in 1994 and 2013, and have not shown a temporal trend similar to that of the
piscivorous species. Most of the concentrations recorded in years after completion of the weir were
statistically similar to those of pre-weir years. There was no immediate increase on concentrations
following 2005, but the increase in concentration between 2008 (0.09 ppm) and 2013 (0.12 ppm) was
significant.
DECEMBER 2015
5.5-92
0.5
due to CRD
Completion
of weir
0.4
Churchill R., Weir
0.3
Pike
Walleye
Whitefish
0.2
n=5
*
0.1
*
*
*
0.0
75
19
80
19
85
19
90
19
95
19
00
20
05
20
10
20
15
20
Year
mean was used; n represents sample size. The upper limit of the mercury concentration scale is equivalent to the 0.5 ppm Health
Canada standard for retail fish.
Figure 5.5.5-3:
Concentrations of Northern Pike, Walleye, and Lake Whitefish From the
Churchill River Upstream of the Weir for 1994–2013
Based on an estimate of approximately 19% for the extent of re-flooded area, the EIS for the Churchill
Weir Project predicted that mercury concentrations in whitefish and pike would increase “slightly to
moderately” after weir construction (Manitoba Hydro and Town of Churchill 1997). In contrast to the
predictions, concentrations have remained similar in whitefish and have significantly decreased in pike for
several years after the completion of the weir. This post-Project reduction in pike mercury concentrations
is inconsistent with the generally observed increase in mercury availability and bioaccumulation after
flooding of boreal reservoirs (Bodaly et al. 2007) or periods of increased river water levels
(Balogh et al. 2006).
In previous studies, biological parameters such as fish age have been used to explain unexpected
patterns in standard means (KHLP 2012). Mercury concentrations are often more strongly associated
with fish age than with fish length (Chumchal and Hambright 2009; Jansen and Strange 2009;
Evans et al. 2005), and length standardization may not adequately standardize mercury concentrations if
the age at a certain length (i.e., growth rate) differs between samples. For the lower Churchill River, mean
DECEMBER 2015
5.5-93
age of whitefish was only slightly lower in post-weir years, and the mean age of pike was similar in preweir and post-weir years. Thus differences in fish age cannot contribute to an explanation of the
unexpected post-Project decrease in standard means of Northern Pike.
One possible explanation for the discrepancy between actual and predicted mercury concentrations is
that the EIS predictions included re-watered habitat (previously wetted habitat which had become
exposed following CRD) in the calculation of flooded area. Nevertheless, approximately 167 ha
(equivalent to 7.5% flooding) were newly inundated after the construction of the weir
(Bernhardt and Posthumus 2003). Perhaps the re-watered and the newly flooded areas on the Churchill
River had a lower methylation potential than the mainly fringing wetlands and bogs flooded by the
reservoirs used in the study by Bodaly et al. (2007). Both the quantity and the quality (lability) of organic
carbon stores in the flood zone affect the rate and duration of methylmercury production
(Bodaly et al. 2004), and it is likely that Churchill River stores were relatively small and of lower quality.
Furthermore, methylmercury bioaccumulation in the food chain may not be closely linked to rates of
methylmercury production (Bodaly et al. 2004). For these reasons, the predictions of fish mercury
concentrations in the Churchill River upstream of the weir may have been overestimated in the EIS.
Nevertheless, it is surprising that concentrations did not increase at all.
5.5.5.5
5.5.5.5.1
Fish mercury concentrations in on-system waterbodies of Area 4 have only rarely exceeded the Health
Canada standard of 0.5 ppm for the commercial sale of fish. Most of these exceedances were for
relatively large fish from commercial (e.g., some of the samples from the Churchill River in 1970–1972;
Table 5.5.5-1) or survey samples with small numbers of fish (i.e., Walleye from NIL in 1982
(Figure 5.5.5-1), Northern Pike from the Churchill River mouth in 1993 (Figure 5.5.5.-2), and pike
(0.79 ppm) and Walleye (0.70 ppm) from Partrige Crop Lake for the only available sample in 1982). The
only large samples of individual fish with standard means exceeding the Health Canada standard were for
36 pike and Walleye each from NIL in 2010, which both had a concentration of 0.53 ppm (Figure 5.5.5-1).
A concentration exceeding 0.5 ppm was also recorded for a commercial samples from off-system
Limestone Lake in 1971/1972, Table 5.5.5-1). Otherwise, the results from several other off-system lakes
in Area 4 indicate the Health Canada standard has not been exceeded pre-CRD (Table 5.5.5-1) or in
more recent years (Table 5.5.5-2). The range of mercury concentrations in fish from off-system
waterbodies in Area 4 is quite large. Considering data across all available years, concentrations in
Walleye were as low as 0.14 ppm (Thomas Lake in 2005) and as high as 0.39 ppm in Waskaiowaka Lake
in 1982 (Table 5.5.5-2). Furthermore, a significant difference in concentrations among years existed for
Waskaiowaka Lake. However, the range in concentrations across lakes and years was not different
compared to that observed for the four (Granville Lake excluded) CAMP off-system reference lakes in the
ROI (see Table 5.5.4-2), indicating that natural variability in fish mercury among waterbodies and over
time can be substantial.
DECEMBER 2015
5.5-94
Table 5.5.5-2:
Standard Mean or Arithmetic Mean Mercury Concentrations with 95%
Confidence Limits, Parts-per-Million, for Northern Pike, Walleye, and Lake
Whitefish from Nine Off-System Lakes in Area 4 for Years 1978–2005
Lake
1978-81
1982
2005
Northern Pike
Christie
-
-
0.218 (0.194–0.244)
Cygnet
-
0.184 (0.143–0.237)
-
Holmes
-
0.255 (0.198–0.312)
Kiask
-
-
0.205 (0.172–0.245)
Recluse
-
0.240 (0.183–0.316)
-
Settee
-
0.250 (0.187–0.333)
-
Thomas
-
1
Waskaiowaka
0.439 (0.367-0.511)
Wood
0.183 (0.126-0.264)*
0.421 (0.352–0.490)
1
-
0.134 (0.111–0.162)
1
1,3
0.233 (0.187–0.279)
-
-
2
Walleye
Caldwell
-
-
0.247 (0.218–0.280)
Christie
-
-
0.290 (0.258–0.327)
Pelletier
-
-
Recluse
-
0.251 (0.188–0.337)
Thomas
-
3
Waskaiowaka
0.202 (0.182-0.224)
Wood
0.160 (0.125-0.205)*
0.381 (0.348–0.417)
4
0.250 (0.206–0.304)
0.140 (0.121–0.162)
2
0.387 (0.311–0.481)
0.266 (0.227–0.311)
-
-
Lake Whitefish
Caldwell
-
-
0.039 (0.033–0.047)
Christie
-
-
0.036 (0.031–0.043)
Kiask
-
-
0.056 (0.045–0.069)
Thomas
-
-
0.042 (0.036–0.048)
Waskaiowaka
-
-
0.036 (0.031–0.042)
Note: Means are based on a minimum of 13 fish.
* Mean was calculated by combining data for at least two years within the indicated time period.
1.
2.
3.
4.
Arithmetic mean (relationship between fish length and mercury concentration was not significant).
Significantly lower than other means for the species in 2005.
Significantly lower from means of other years for the lake.
Significantly higher than other means for the species in 2005.
DECEMBER 2015
5.5-95
Together with the Nelson River in Area 2 (see Section 5.5.3.4.1), the Churchill River has the most
extensive record on mercury concentrations in Lake Sturgeon within the ROI. The available data for
individual fish all come from the CAMP sampling location near the confluence of the Little Churchill River
and were collected from 2009–2014. They support the conclusion based on data from Area 2 that
sturgeon generally have low mercury concentrations (in the range of 0.05–0.2 ppm), but that some of the
larger (> 1,000 mm fork length) individuals can even exceed the 0.5 ppm Health Canada standard for
retail fish (Figure 5.5.5-4).
0.7
Churchill River
Hayes River
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0 200
400
600
800
1000
1200
1400
Length (mm)
Significant regression lines are shown. The stippled line indicates the 0.5 ppm Health Canada standard for retail fish.
Figure 5.5.5-4:
Relationship Between Mercury Concentration and Fork Length for Lake
Sturgeon From the Churchill River at the Little Churchill River for 2010–2014
and the Hayes River for 2009–2013
5.5.5.5.2
Evolution of Fish Mercury Concentrations in Relation to
Hydroelectric Development
As discussed for each of the focal waterbodies (see Sections 5.5.5.4.1 and 5.5.5.4.2) there is no
indication that the reduction and increased variability in Churchill River flows and water levels as a result
of CRD increased mercury concentrations in fish from the river or a riverine lake in Area 4. These results
are in line with findings for the Eastmain River in Québec for which a 90% flow reduction had no obvious
DECEMBER 2015
5.5-96
effect on mercury concentrations in Lake Whitefish and Northern Pike (Schetagne and Verdon 1999a).
There was no evidence of a downstream effect on fish mercury concentrations in the Churchill River.
Contrary to EIS predictions, mercury concentrations in Lake Whitefish from the lower Churchill River did
not increase and concentrations in Northern Pike significantly decreased after the construction of the
Churchill Weir and the associated minor flooding.
DECEMBER 2015
5.5-97
5.5.6
•
Effects of Changes in Hydroelectric Development
on Fish Mercury Concentrations in the Region of
Interest
Information on muscle mercury concentrations in fish species from the ROI exists since 1969 and
includes almost 54,000 analyses of individuals from 23 species from more than 200 waterbodies. The
vast majority of the results are for Lake Whitefish (17.2%), Northern Pike (32.1%), and Walleye
(29.8%), which together account for almost 80% of the individual data. In addition, more than 1,000
analyses of composite samples of fish from commercial captures are available, mainly for years
1969–1985.
•
Fish mercury concentrations were impacted by hydroelectric development throughout the ROI,
particularly by the inundation of soils and vegetation as a result of reservoir flooding. The magnitude
and temporal extent of increases in concentrations varied mainly depending on the intensity of
flooding and fish trophic position. These findings are well established and remain unaffected by the
existing data limitations.
•
Research within Area 3 of the ROI in the mid-1970s for the first time clearly attributed the increase in
fish mercury concentrations after flooding to a greater supply of inorganic mercury from the leaching
of humic rich soils and an increase in mercury bioavailability due to bacterial mercury methylation.
•
Fish mercury concentrations increased relatively rapidly after flooding to reach a transient maximum,
after which concentrations declined over an extended period of time, relatively quickly at first, and
more gradually later. Maximum concentrations in piscivorous species (Northern Pike, Walleye,
Sauger) from the more extensively flooded lakes reached approximately 2 ppm, whereas maxima in
large bodied species of lower trophic levels generally did not exceed 0.6 ppm and remained below
0.3 ppm in Lake Whitefish. Maximum concentrations were usually reached within 3–9 years
post-flood in Northern Pike, Walleye, and Lake Whitefish, with the latter species often being at the
lower end of the range. Maxima represented a 1.4–8.7 fold increase in mercury concentration
compared to those from pre-flood conditions. The increases for Lake Whitefish were similar or even
higher (e.g., Long Spruce forebay, SIL) compared to pike and Walleye from lakes with little or
moderate flooding (i.e., < 100%), whereas the increases were larger in the two piscivorous species
for the more extensively flooded lakes (e.g., Rat and Notigi).
•
The time to reach minimum concentrations after peaking was quite variable between lakes and
species, spanning a range from slightly less than 10 years to 30 years. In almost all cases minima
were either measured for the last year of sampling or occurred in 2005 and were followed by mostly
significantly higher concentrations in subsequent years.
•
Based on the entire data set for the ROI, mean mercury concentrations of piscivorous fish species
from on-system waterbodies have regularly and often substantially exceeded the 0.5 ppm Health
Canada standard for the commercial sale of fish. These exceedances have typically been observed
for 5–25 years but in some cases for more than 35 years after flooding. Mean concentrations in fish
occupying lower trophic levels have rarely exceeded the standard for commercial sale.
•
With few exceptions (e.g., Northern Pike and Walleye from Rat Lake) current (2010–2014) mean
concentrations in on-system waterbodies are all below the 0.5 ppm standard for the commercial sale
DECEMBER 2015
5.5-98
of fish, but individual (large) pike and Walleye fish may reach concentrations of 1 ppm. Mean
concentrations in Northern Pike and Walleye for the large number of off-system lakes in the ROI have
always been lower than 0.5 ppm, although variability among lakes and over time has been
substantial, including standard means as high as 0.38 ppm. Standard means for whitefish from offsystem lakes have been generally below 0.05 ppm.
•
The lower Churchill River (Area 4) was affected by CRD mainly by decreased and variable flows,
amounting to an almost 80% reduction at the Missi Falls CS. There is no indication that these
changes in the hydrology increased mercury concentrations in fish from Northern Indian Lake and the
Churchill River at and below the confluence with the little Churchill River.
•
Both historic (1970s) and increasingly current (since 2002) data on mercury concentrations in Lake
Sturgeon indicate that this species generally has low mercury concentrations in the range of
0.05-0.2 ppm, but that some of the larger (> 1,000 mm fork length) individuals can reach
concentrations of 0.6 ppm.
DECEMBER 2015
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5.5.7
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5.5.7.1
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WATER – FISH QUALITY
5.6
Fish Quality
5.6.1
Introduction
Fish quality was selected as a Regional Study Component (RSC), because reduced quality can affect
domestic fish consumption and can reduce the market price of fish harvested by the commercial fisheries,
which are key economic activities in many of the affected communities.
Fish quality, for the purpose of this document, is considered primarily in terms of:
•
the palatability of the fish (e.g., taste and texture); and
•
the rate of infestation (RI) of the tapeworm Triaenophorus crassus, in Lake Whitefish
(Coregonus clupeaformis).
PALATABILITY
Palatability can directly affect the acceptability of fish as a domestic food source. Over the years, most of
the First Nations in the Regional Cumulative Effects Assessment (RCEA) Region of Interest (ROI) have
expressed concerns, under the auspices of the Northern Flood Agreement, regarding the reduced quality
of fish from impacted waterbodies, which they attribute to the effects of hydroelectric development. At the
request of some of these communities, studies have been conducted to evaluate the quality of fish for
human consumption when prepared using traditional methods. These studies will be discussed, by area,
in the following sections.
LAKE WHITEFISH RATES OF T. CRASSUS INFESTATION
Triaenophorus crassus infects multiple hosts during its life cycle, but it is an intermediate phase that forms
visible, yellowish cysts in the muscle of, among other species, Lake Whitefish and Cisco (Coregonus
artedi) that is of primary concern. Although not harmful to humans (i.e., humans are not a viable host), the
cysts are considered objectionable in appearance and undesirable, affecting the market price of
commercial Lake Whitefish catches and, thus, the economic viability of many fisheries. The Freshwater
Fish Marketing Corporation (FFMC) grades the quality of Lake Whitefish from lakes with commercial
fisheries based on their RI (RI = number of cysts per 100 lbs [45.4 kg] of dressed [gutted and cleaned for
market] fish) with T. crassus. As the number of cysts in the muscle of fish increases, the marketability of
the catch decreases. Currently, the FFMC grades fish to two levels of marketability: “export” and “other”
(“other” was formerly subdivided into “continental” and “cutter”). It is important to note that the grade or
classification of a given commercial fishery is determined by the worst result during inspection. Even if
there are abundant export quality fish in a lake, small numbers of lower quality fish will result in a grade of
“other” for the entire fishery. Until 1988, RI values of 0–50 were graded as “export”, values of 51–80 were
graded as “continental”, and values greater than 80 were graded as “cutter” by the FFMC
(FFMC unpublished [unpubl.] data). The current FFMC approach grades all RI values of 0–50 as “export”
and everything higher as “other”. Canada Department of Fisheries and Oceans (DFO) has used lake
classifications for Lake Whitefish with an export range of 0-40 cysts/100 lbs, slightly different than the
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range used by the FFMC. The grade of Lake Whitefish can greatly affect its marketability. For example,
the FFMC prices to fishers during the 2013/2014 commercial fishing season for “export” Lake Whitefish
were up to $0.75/kg ($0.34/lb) higher than for “other”.
OTHER FISH QUALITY ISSUES
Recently, with the arrival of the invasive Rainbow Smelt (Osmerus mordax) in the RCEA ROI, there have
often been reports of “belly burn” in predatory fish such as Walleye (Sander vitreus) if the fish are not
cleaned shortly after capture. This is caused by an enzyme in smelt that increases the decomposition rate
of the predatory fish’s stomach following its death; therefore, “belly burn” is a function of the presence of
smelt in the predatory fish’s diet and is not connected to hydroelectric development. As such, this aspect
of fish quality is not included in the following discussion.
Mercury in fish also affects its acceptability for domestic consumption and commercial sale. Due to its
relative importance and the quantity of available information, mercury in fish is discussed in detail in its
own chapter (Mercury in Fish, Chapter 5.5).
5.6.1.1
Pathways of Effect
PALATABILITY
There are no known linkages between hydroelectric development in the RCEA ROI and the change in the
palatability of fish reported by the First Nations. A linkage diagram has, therefore, not been provided for
palatability. However, it should be noted that hydroelectric development can cause changes to fish diet,
water quality, water temperature, algae, and growth rates, all of which can, in turn, affect the taste and
texture of fish.
It should be noted, however, that cyanobacteria (blue-green algae) and actinomycetes bacteria produce
compounds (geosmin and 2-methylisoborneol) that have been linked to objectionable or off-flavours
(often described as muddy, earthy, or mouldy) in fish (Persson 1980; Yurkowski and Tabachek 1980;
Schrader and Blevins 1993). High levels of these compounds have been found in nutrient rich
waterbodies which contain cyanobacteria blooms including; aquaculture ponds (Lorio et al. 1992) and
flooded lakes and reservoirs (Yurkowski and Tabachek 1980; Izaguirre et al. 1999). Yurkowski and
Tabachek (1980) stated that the presence of this off-flavour in several species of fish from Cedar Lake,
Manitoba (MB) in the mid-1970s was likely the result of input of additional organic matter and
corresponding increases in cyanobacteria following construction of the Grand Rapids Generating Station
(GS) and flooding of the lake. However, they were unable to directly link the muddy flavour to a source at
the time it occurred and the problem has not been reported since. Information on cyanobacteria blooms in
lakes in the RCEA ROI is limited, but anecdotal evidence suggests they are uncommon. As a result, it
seems unlikely that fish palatability in the RCEA ROI has been affected by proliferation of blue green
algae/cyanobacteria.
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5.6-2
The life history of T. crassus has been well documented (Miller 1952; Lawler and Scott 1954;
Lawler 1955; Watson and Dick 1979a). The parasite requires three hosts to complete its life cycle. The
first larval stage is found in cyclopoid copepods (a type of zooplankton). The second host, in which the
parasite forms cysts in the muscles, is typically a coregonine fish (e.g., Lake Whitefish and Cisco). The
final host, in which the parasite matures to an adult in the intestine, is typically Northern Pike
(Esox lucius). During Northern Pike spawning in the spring, the adult T. crassus detaches itself from the
gut wall of the fish and, as it passes out of the fish and into the water, releases its eggs in littoral areas.
The eggs hatch after one to two weeks and the free-swimming larvae are then consumed by copepods
(usually Cyclops bicuspidatus in the RCEA ROI). When the copepod is, in turn, consumed by Lake
Whitefish or Cisco, the parasite is released, penetrates the lining of the stomach, and becomes
embedded in the tissue of the fish. Northern Pike feeding on these Lake Whitefish become infected and
the cycle continues.
There are several effects that could increase the T. crassus RI in Lake Whitefish, including an increase in
the abundance of cyclopoid copepods, increased proportions of copepods in Lake Whitefish diets
(as opposed to benthic prey items), and increased abundance of Northern Pike (Figure 5.6.1-1).
Pulkkinen and Valtonen (1999) have also suggested that there is an increase in the annual accumulation
of cysts in fish hosts that is independent of dietary changes, but is associated with a threshold intensity of
infestation above which the probability of acquiring further parasites increases. This is likely a result of a
compromised immune system in heavily infested fish.
In some lakes where there are multiple, distinct populations of Lake Whitefish, cyst counts will vary
between populations. Dietary changes associated with growth can also result in multiple RI, by size
cohort, within the same population in a lake. For example, Lake Whitefish may switch from feeding on
zooplankton as juveniles to consuming larger, benthic prey items as adults. Commercial fishers generally
target the whitefish with the lower cyst counts as these are sold at higher prices. In some lakes, changes
in water levels, habitat, and/or hydrology, which may all be effects of hydroelectric development, have
caused fish to redistribute themselves and the Lake Whitefish with the lower cyst counts are no longer in
the traditional fishing areas (Bodaly et al. 1984). Redistribution of Lake Whitefish populations within or
between lakes may also expose them to increased rates of infestation in the copepods they consume.
Increases in copepod and Northern Pike abundance or redistribution of any of the three hosts, which may
occur with flooding and reduction of velocities in impounded waterbodies, are the most likely linkages
between hydroelectric development and increases in rates of T. crassus infestation in Lake Whitefish
(Figure 5.6.1-1).
5.6.1.2
Indicators and Metrics
PALATABILITY
Indicators for fish palatability are: a) the acceptability of fish to community members; and b) the results of
scientific tests conducted on fish palatability. As mentioned above, fish taste is a very subjective quality,
influenced by a variety of factors. Because the results of the scientific studies generally differ from the
DECEMBER 2015
5.6-3
experiences expressed by the community, information is provided on both with no attempt to determine
which is correct.
The indicator used for Lake Whitefish quality regarding rate of T. crassus infestation is the RI or number
of cysts per 100 lbs (45.4 kg) of dressed (gutted and cleaned for market) commercial whitefish.
5.6.1.3
Data Limitations
The absence of any scientific assessments on fish palatability before hydroelectric development does not
allow for quantitative assessments of change over time. Assessments can only be made between onsystem and off-system waterbodies.
With the exception of Southern Indian Lake (SIL), there are few, robust T. crassus RI datasets for
waterbodies either before or after hydroelectric development, which limits the ability to determine if
changes have occurred in many of these locations.
DECEMBER 2015
5.6-4
Arrow width is not an indication of magnitude.
Figure 5.6.1-1:
DECEMBER 2015
Linkage Diagram Showing Potential Pathways of Effect of Hydroelectric Development and Other Factors on Fish Quality
5.6-5
5.6.2
Area 1: Lake Winnipeg Outlet to Kelsey Generating
Station
Area 1 comprises the reach of the Nelson River from the outlet of Lake Winnipeg to the Kelsey (GS)
(Map 5.6.2-1). The upper portion of Area 1 consists of the Outlet Lakes area, including Playgreen Lake.
The river flows via the east and west channels of the Nelson River to Cross Lake. Downstream of Cross
Lake, the river passes over a series of rapids to Sipiwesk Lake and then, prior to the construction of the
Kelsey GS, through several more rapids to Kelsey Rapids, which is the site of the Kelsey GS. Several
hydroelectric developments have been constructed in the area. Kelsey GS at Kelsey Rapids on the
Nelson River caused some flooding upstream as far as Sipiwesk Lake. Lake Winnipeg Regulation (LWR).
via three diversion channels in the Outlet Lakes area, increased Lake Winnipeg outflow capacity by up to
50%, affecting several downstream waterbodies. The Jenpeg GS, constructed on the west channel of the
Nelson River where it entered Cross Lake, flooded the river channel immediately upstream and regulates
outflows from Lake Winnipeg along the west channel of the Nelson River. LWR can also affect seasonal
pattern of flows along the west channel of the Nelson River and downstream, with peak flows now
occurring during the winter months and lower flows during the open water season in low to average flow
years. Flow regulation at Jenpeg also affects water levels and flows in Cross Lake and the river reach
between Cross Lake and Sipiwesk Lake. Detailed information regarding project descriptions for
hydroelectric developments in Area 2 and their effects on the local water regime can be found in
Hydroelectric Development Project Description in the Region of Interest, Part II Appendices 2A, 2D, and
2E and in Water Regime, Section 4.3.2.
5.6.2.1
Approach and Methods
PALATABILITY
Canada Department of Fisheries and Oceans was subcontracted by North/South Consultants Inc. to
conduct a taste-test study in 1993–1994 (Davies et al. 1998a). The Analytical Services Section of DFO
had a specific protocol for analyzing fish quality by qualitatively assessing fish texture, colour, interior and
exterior appearance, smell, and taste. Samples were also tested for a wide range of metals and
pesticides. The protocol is outlined in DFO's "Fish Products Inspection Procedure Manual". Samples of
Lake Whitefish, Northern Pike, and Walleye were obtained from Playgreen and Little Playgreen lakes and
Mossy Bay in Lake Winnipeg and were prepared using traditional methods (boiling or pan-frying). The fish
evaluated for quality were classified as either “satisfactory” (i.e., they passed the qualitative assessment
of parameters listed above) or “unsatisfactory” (i.e., they failed one or more of the qualitative
assessments) by an individual trained to detect substances contaminating fish flesh.
Within Manitoba, FFMC currently grades Lake Whitefish marketability from a given waterbody as either
“export” or “other” based on T. crassus RI. To arrive at this grade, a set number of fish are inspected
periodically. For each inspected fish, the total weight is recorded (± 25 g) and, if necessary, converted to
DECEMBER 2015
5.6-6
pounds. The fish are filleted and thin slices (no thicker than 6.35 mm [¼”]) are made at right angles to the
length of each fillet. The number of T. crassus cysts in each slice are counted and the RI is calculated
according to the following formula:
RI = (number of cysts/lb of fish samples) × 100
It is important to note that cyst counts describing “export” and “other” quality Lake Whitefish have
historically differed between surveys. Some surveys (e.g., SIL studies from the 1970s and 80s) have used
federal government (i.e., DFO) guidelines, for which a range of 0-40 cysts/100 lbs (dressed weight) is
considered export and others have used the FFMC range of 0-50 cysts/100 lbs to describe export quality
fish. Ranges used for each data set will be provided when possible.
5.6.2.2
PALATABILITY
In response to concerns of a decline in the quality of fish (in terms of taste, texture, and size) expressed
by Norway House, North/South Consultants Inc. initiated a taste-test study on fish from Little Playgreen
Lake (including the Jack and Gunisao rivers), Playgreen Lake, and Mossy Bay in Lake Winnipeg
(Davies et al. 1998a).
Rates of infestation by T. crassus cysts in Lake Whitefish have been recorded during scientific
investigations in many waterbodies in Area 1 since the 1950s, including Sipiwesk Lake (Schlick 1966a;
Sunde 1965a), Walker Lake (Sunde 1964, 1965a), Drunken Lake (Nelson River Group [NRG] 1986) and
Cross, Duck, Kiskitto, Pipestone, and Playgreen lakes (Sunde 1965a). Mackay et al. (unpubl. data)
summarized cyst count data from the Sipiwesk Lake commercial fishery between 1974 and 1988. Sowe
(1986) examined the factors influencing T. crassus abundance in Lake Whitefish from several
commercially fished lakes, including Playgreen, Sipiwesk, and Walker lakes in Area 1.
5.6.2.3
The FFMC routinely samples Lake Whitefish from Manitoba lakes with commercial fisheries (including at
least 10 lakes in Area 1) and counts cysts from dressed fish in their laboratory in Winnipeg. Fish are then
graded based on their RI. Current (2015) Lake Whitefish grading results (unpubl. data) were obtained for
comparison with earlier data.
DECEMBER 2015
5.6-7
Scale: 1:1,227,000
Rive
r
Kelsey G.S.
Assessment
6
Pikwitonei
(NAC)
Nels
o
n
Thompson
Legend
Wuskwatim
G.S.
Infrastructure
Thicket Portage
(NAC)
Transmission Line (Existing)
Rail
Highway
RCEA
Area 1
Snow Lake
Sipiwesk
Lake
Note: Northern Affairs Community (NAC)
Duck
Lake
Wabowden
(NAC)
373
Cross Lake
Herb Lake Landing
(NAC)
Walker
Lake
Hudson Bay
Churchill
Pimicikamak
39
6
Drunken
Lake
Cross Lake (NAC)
Jenpeg
G.S.
Pipestone
Lake
n
Kiskittogisu
Lake
Playgreen
Lake
Ne
lso
File Location: J:\MYP\MH_RCEA\Fish_Quality\PHASE_2\Mxd\20151205_RCEA_PhaseII_AE_FQ_EE_FishQualityAssessmentAreaLakeWinnipegOutletToKelseyGSRCEAArea1_cp.mxd
Kiskitto
Lake
River
Thompson
DATA SOURCE:
Government of Canada, Province of Manitoba, Manitoba Hydro
Norway House Cree Nation
Playgreen
Lake
Norway House (NAC)
CREATED BY:
COORDINATE SYSTEM:
0
10
20 Kilometres
DATE CREATED:
REVISION DATE:
27-JUL-15
05-DEC-15
VERSION NO:
QA/QC:
1.0
0
LAKE
WINNIPEG
10
20 Miles
Fish Quality Assessment Area
Lake Winnipeg Outlet to
Kelsey Generating Station
RCEA Area 1
Map 5.6.2-1
5.6.2.4
Changes in Indicators over Time
PALATABILITY
Members of the Northern Flood Committee (including the communities of Norway House and Cross Lake)
filed a claim in 1984, under the auspices of the Northern Flood Agreement, alleging that the modification
of the water regime by Manitoba Hydro had adversely affected domestic fisheries, including several in
Area 1 waterbodies. The primary impact identified by Norway House members with regards to the
domestic fishery was a decline in the taste, texture, and size of fish in the domestic harvest (see People,
Section 3.5.10). Lake Whitefish, Northern Pike, and Walleye from Little Playgreen (including the Jack and
Gunisao rivers) and Playgreen lakes and Mossy Bay in Lake Winnipeg were captured and forwarded to
DFO in 1993 and 1994 for analysis of colour, texture, smell and, in 1994 only, for taste
(Davies et al. 1998a). Results of those tests identified all samples as “satisfactory”, as compared to
“unsatisfactory”. Further complicating the issue, studies have shown extensive movements of fish
between waterbodies in Area 1 (e.g., fish movement between Playgreen Lake and Lake Winnipeg;
Davies et al. 1998b).
Cross Lake members also have stated that the taste and texture of fish in Cross Lake has declined since
hydroelectric development. The domestic fishing program harvests fish from Cross Lake during the open
water period and other lakes (see People, Section 3.5.5) during the winter period. Large quantities of fish
have been provided to and consumed by the community. However, some Cross Lake members have
stated that they prefer fish from off-system areas and some members have stated that they have
purchased fish from those waterbodies (S. Davies pers. comm. 2015).
LAKE WHITEFISH T. CRASSUS RATE OF INFESTATION
Generally, Lake Whitefish from most Area 1 waterbodies sampled between 1960 and 1990 were graded
as export quality (Table 5.6.2-1). Only Walker Lake (Sunde 1964, 1965a), an off-system lake, was graded
as the lower value “other” classification (identified as continental using the older grading classification). In
1980, the Walker Lake fishery was downgraded from continental to cutter, which meant that harvesting of
Lake Whitefish had become uneconomical in the lake (NRG 1986). In addition, since 1990, five Area 1
lakes (Drunken, Duck, Kiskitto, Pipestone, and Sipiwesk) previously identified as export have been
downgraded to other (Table 5.6.2-1). However, historical data for those lakes were relatively limited
(in survey duration and/or sample size) for all but Sipiwesk (Schlick 1966a; Sunde 1965a; NRG 1986;
Sowe 1986; Mackay et al. unpubl. data), which may have affected the original classification.
DECEMBER 2015
5.6-9
Table 5.6.2-1:
Historical and Current Grades for Lake Whitefish in Area 1 Waterbodies Based
on Triaenophorus crassus Cyst Counts
1,2
1980–1990
3
2006–2011
4
2015
4
Waterbody
Pre-1980
Cross Lake
Export
-
Export
Export
-
Export
-
Other
Duck Lake
Export
-
Other
Other
Kiskitto Lake
Export
-
Other
Other
Kiskittogisu Lake
-
-
Export
Export
Nelson River
-
-
Other
Other
Pipestone Lake
Export
-
Other
Other
Playgreen Lake
Export
Export
Export
Export
Sipiwesk Lake
Export
Export
Other
Other
Walker Lake
Other
Other
Other
Other
Lake Winnipeg
Export
Export
Export
Export
Drunken Lake
1.
2.
3.
4.
Export = 0–50 cysts/100 lbs of fish (dressed weight); Other (includes Continental and Cutter grades) = > 50 cysts/100 lbs of
fish (dressed weight).
Data sources: Sunde (1964, 1965a); Schlick (1966a); Sowe (1986); Mackay et al. (1990).
Data sources: Sowe (1986); Mackay et al. (1990).
Data sources: FFMC (unpubl. data).
5.6.2.5
Quality in Area 1
PALATABILITY
There is no scientific evidence to suggest that the taste, texture or palatability of fish has been affected by
hydroelectric development in Area 1. However, the people who consume the fish in the communities have
clearly identified this as an issue that is related to hydroelectric development.
LAKE WHITEFISH T. CRASSUS INFESTATION RATES
As illustrated in the pathways of effects diagram (Figure 5.6.1-1) the RI for T. crassus in the muscle of
Lake Whitefish can be linked to hydroelectric development. Some of these links have been established
for waterbodies in other areas (e.g., SIL; see Section 5.6.4). However, there have been few detailed T.
crassus studies in Area 1 waterbodies and no definitive link has been established. For example, although
LWR was linked to a decline in the Lake Whitefish stocks in Cross Lake, the grade of the fishery
remained export quality. There does not appear to be any known change to Northern Pike or zooplankton
DECEMBER 2015
5.6-10
abundance that may have affected T. crassus counts in Area 1 waterbodies, though more detailed
studies would be required to completely rule out any linkage.
DECEMBER 2015
5.6-11
5.6.3
Area 2: Split Lake to Nelson River Estuary
Area 2 comprises the reach of the Nelson River from the Kelsey GS to the Nelson River Estuary. Major
waterbodies within this area include Split Lake, Gull Lake, Stephens Lake, Long Spruce reservoir,
Limestone reservoir, and the lower Nelson River (Map 5.6.3-1). Several hydroelectric developments have
been constructed in the area. Kelsey GS at Kelsey Rapids on the Nelson River caused some upstream
flooding (Area 1), but there were negligible effects to downstream waterbodies. Kettle GS at Kettle Rapids
on the Nelson River affected the water regime and fish habitat in the reach of the river extending to Gull
Rapids, causing some flooding between Gull and Kettle rapids. Beginning in mid-1976, LWR affected the
seasonal distribution of flow as it entered Split Lake and Churchill River Diversion (CRD) increased the
total inflow to Split Lake. Long Spruce GS and Limestone GS on the Nelson River each caused small
amounts of upstream flooding and, depending on local conditions, dewater large areas of the
un-impounded downstream riverbed on a daily or weekly basis. Detailed information regarding project
descriptions for hydroelectric developments in Area 2 and their effects on the local water regime can be
found in Hydroelectric Development Project Description in the Region of Interest, Part II Appendices 2A,
2B, 2D, 2F, 2G, 2H, and 2L and in Water Regime, Sections 4.3.2 and 4.3.4.
5.6.3.1
PALATABILITY
Prior to construction of the Keeyask GS, and to address community concerns regarding a perceived
reduction in fish quality in some Area 2 waterbodies, members of Tataskweyak Cree Nation (TCN) at Split
Lake, York Factory First Nation (YFFN) at York Landing, and Fox Lake Cree Nation (FLCN) at Bird were
asked to judge the palatability of Lake Whitefish, Northern Pike, and Walleye from waterbodies of their
choice in the vicinity of each community (Ryland and Watts 2002a, 2004a, 2004b). The acceptability of
fish from lakes that had previously been affected by hydroelectric development was compared to fish from
at least one unaffected nearby lake.
Waterbodies sampled for fish used in the palatability tests included the Aiken River, Split Lake, Assean
Lake, Gull Lake, and Stephens Lake and from three of the Adverse Effects Agreements (AEA) offsetting
lakes: Atkinson Lake, War Lake, and Waskaiowaka Lake and the Limestone reservoir. The AEA offsetting
lakes were used as regional reference lakes that will not experience direct physical effects of the Keeyask
Generation Project and by specific request of the three communities.
DECEMBER 2015
5.6-12
Scale: 1:1,180,114
Hudson Bay
Churchill
HUDSON
BAY
Thompson
RCEA
Area 2
Waskaiowaka
Lake
eston e
Lim
Conawapa
G.S.
er
Riv
Little Limestone
Lake
Fox Lake Cree Nation
Fox Lake (Bird)
Kettle
G.S.
elso
Clark N
Lake
Tataskweyak (Split Lake)
Assean
Lake
File Location: J:\MYP\MH_RCEA\Fish_Quality\PHASE_2\Mxd\20151205_RCEA_PhaseII_AE_FQ_EE_FishQualityAssessmentAreaKelseyGStoNelsonREstuaryRCEAArea2_cp.mxd
Split Lake
Kelsey
G.S.
n
Moose Nose
War Lake First Nation
Lake
York Factory
First Nation
York Landing
(Kawechiwasik)
War
Lake
Limestone G.S.
Angling
Lake
Stephens
Lake
Long Spruce G.S.
River
Gillam Fox Lake Cree Nation
Keeyask
A Kwis Ki Mahka Reserve
G.S.
Butnau
Lake
280
Tataskweyak Cree Nation
Nelson River
Ilford (NAC)
290
Atkinson
Lake
Shamattawa
First Nation
DATA SOURCE:
Government of Canada, Province of Manitoba, North/South Consultants and
Manitoba Hydro.
Legend
CREATED BY:
COORDINATE SYSTEM:
Assessment
0
0
10
20 Kilometres
10
20 Miles
DATE CREATED:
REVISION DATE:
27-AUG-15
07-DEC-15
VERSION NO:
QA/QC:
1.0
Generating Station (Under Construction)
Highway
Rail
Kelsey Generating Station to
Nelson River Estuary
RCEA Area 2
Map 5.6.3-1
Species-specific size ranges of fish (Lake Whitefish: 1,400–2,000 g; Northern Pike: 2,700–3,000 g;
Walleye: 700–1,000 g) were collected with gill nets set three to five weeks prior to taste testing. Fillets
(Northern Pike and Walleye) or scaled and eviscerated whole fish (Lake Whitefish) were prepared on-site
and stored frozen until taste sample preparation. The samples consisted of small (less than 10 g) pieces
of fried (Northern Pike and Walleye) or boiled and deboned flesh (Lake Whitefish) prepared by local
cooks, that were presented to panellists three to four at a time, with each piece representing a coded
sample from each lake. Fish species were evaluated on separate days. Between 23 and 48 panellists,
stratified by age (16–35, 36–55, greater than 55 years) and consumption habit (eat fish every day, three
to four times per week, one to two times per week, three times per month) tasted fish in each community.
Panellists expressed their acceptability of the fish based on a seven-point category scale from “like very
much” (7) to “dislike very much” (1) (for a full list of categories see Ryland and Watts 2002a; 2004a, b).
Analysis of variance followed by, if applicable, Duncan’s test for means comparisons was conducted on
the numerical categories of fish acceptability using PROC GLM (SAS, PC Version 8.2) to determine if
there were significant differences among the acceptability of fish of the same species from different
locations or among panellist age categories.
Methods used by the FFMC to grade commercial Lake Whitefish based on infestation rates is described
in detail in Section 5.6.2.1.
In addition to the routine commercial samples assessed by the FFMC, 87 Lake Whitefish were captured
for T. crassus analysis as part of the Keeyask environmental studies from Split, Gull, Stephens and
Waskaiowaka lakes during summer/fall of 2003–2006. Sampled fish were gutted and stored at -18°C in
freezers for subsequent delivery to the FFMC (Winnipeg, MB) where RI was calculated using established
FFMC methods.
5.6.3.2
PALATABILITY
To describe existing conditions in the study area, fish palatability studies were conducted in the
communities of Split Lake (TCN) on fish from Split, Gull, Assean, and Waskaiowaka lakes from 20–22
October, 2003 (Ryland and Watts 2004a), York Landing (YFFN) on fish from Split Lake, War Lake, and
the Aiken River from 29 April to 6 May, 2002 (Ryland and Watts 2002a), and Bird (FLCN) on fish from
Gull, Stephens, and Atkinson Lakes, and the Limestone reservoir from 28–30 October, 2003 (Ryland and
Watts 2004b).
The effects of previous hydroelectric development in northern Manitoba, including the effects on fish
palatability, were assessed in the Split Lake Resource Management Area as part of the Split Lake Cree
Post Project Environmental Review (Split Lake Cree - Manitoba Hydro Joint Study Group 1996a, b, c).
DECEMBER 2015
5.6-14
LAKE WHITEFISH T. CRASSUS RATES OF INFESTATION
Extensive historical information on Lake Whitefish infestation rates with T. crassus cysts were recorded in
the 1950s and 1960s (Schlick 1967; Sunde 1965a, b). These surveys included Split Lake in Area 2, which
was sampled in 1959 and from 1962–1966. Four of the AEA offsetting lakes for the Keeyask Generation
Project (Atkinson, War, Moose Nose, and Waskaiowaka lakes) were also sampled historically by DFO
and/or by the Fisheries Branch of the Manitoba Department of Mines and Natural Resources
(Sunde 1965a; Schlick 1967, 1979; Moshenko 1968). Historical information on rates of infestation of Lake
Whitefish by T. crassus is also available from commercial monitoring in Split Lake by the FFMC
(FFMC unpubl. data).
The effects of previous hydroelectric development in northern Manitoba, including the effects to rates of
infestation of Lake Whitefish by T. crassus, were assessed in the Split Lake Resource Management Area
as part of the Split Lake Cree Post Project Environmental Review (Split Lake Cree - Manitoba Hydro Joint
Study Group 1996a, b, c).
Lake Whitefish were also captured for T. crassus analysis as part of the Keeyask environmental studies
from Split, Gull, and Stephens lakes in Area 2 and from Waskaiowaka Lake during summer/fall of
2003-2006.
5.6.3.3
The FFMC routinely samples Lake Whitefish from Manitoba lakes with commercial fisheries and counts
cysts from dressed fish in their laboratory in Winnipeg. Fish are then graded based on their RI. Current
(2015) Lake Whitefish grading results (unpubl. data) were obtained from Angling, Assean, Butnau, Little
Limestone, Split, and Stephens lakes for comparison with earlier data.
5.6.3.4
PALATABILITY
Members of TCN, YFFN, and FLCN all expressed concerns about the decline in fish quality
(as determined by taste and texture) in area waterbodies affected or potentially affected by hydroelectric
development. To address these concerns, fish palatability tests using Lake Whitefish, Walleye, and
Northern Pike were conducted in each community (Ryland and Watts 2002a, 2004a, b). The results of
those studies identified ratings for all samples as “like slightly” or “like moderately”. Panellists from all
three communities showed some preference for fish from lakes that have not been previously affected by
hydroelectric development. Generally, TCN and FLCN panellists rated fish, particularly Walleye, from Gull
Lake as less acceptable than fish from Waskaiowaka Lake, War Lake, Atkinson Lake, and Assean Lake.
There was no significant difference in the mean acceptability of fish species sampled from different
waterbodies by YFFN panellists. However, it should be noted that the results of the palatability study at
York Landing do not reflect the views of most community members on the taste of fish species used in
the study. In particular, there was a concern expressed by some members that no fish were tested that
were captured when water temperatures were warmer and taste differences would be more noticeable.
DECEMBER 2015
5.6-15
Historical RI data from Area 2 were restricted to Split Lake. More recently, data have been collected from
an increasing number of Area 2 waterbodies (Table 5.6.3-1). Of all the sampled lakes, only Split Lake has
been graded as export quality and it has consistently been graded as such since the 1960s
(Sunde 1965a, Schlick 1967, FFMC unpubl. data). All other waterbodies have been graded as either
cutter or continental (i.e., other). There have been no noticeable changes to the RI of T. crassus in Area 2
lakes and no obvious links to hydroelectric development in the region.
Table 5.6.3-1:
Historical and Current Grades for Lake Whitefish in Area 2 Waterbodies
Based on Triaenophorus crassus Cyst Counts
Waterbody
Pre-1980
Angling Lake
1,2
1980–1990
3
1991–2005
3, 4
2006–2011
3, 4
2015
3
-
-
-
-
Other
-
-
-
-
Other
Export
-
-
-
-
Butnau Lake
-
-
-
-
Other
Clark Lake
-
-
-
-
-
Limestone River
-
-
-
Other
Other
-
-
-
-
Other
Other
-
-
-
-
-
-
-
Other
Other
Export
Export
Export
Export
Export
-
-
-
-
Other
Export
-
-
-
-
Other
-
Other
-
-
Assean Lake
Atkinson Lake
5
Little Limestone Lake
Moose Nose Lake
Nelson River
Split Lake
Stephens Lake
War Lake
5
Waskaiowaka
1.
2.
3.
4.
5.
5
5
Export = 0–40 cysts/100 lbs of fish (DFO) or 0–50 cysts/100 lbs of fish (FFMC); Other (includes Continental and Cutter
grades) = > 40 or > 50 cysts/100 lbs of fish (dressed weight).
Data sources: Sunde (1965a); Schlick (1967); Moshenko (1968); Schlick (1979).
Data source: FFMC (unpubl. data).
Data source: Keeyask Hydropower Limited Partnership (2012).
Adverse Effects Agreements (AEA) offsetting lakes; though not technically in Area 2, these lakes have often been used as
supposedly unaffected comparisons with Area 2 lakes that may be affected by hydroelectric development.
5.6.3.5
Quality in Area 2
PALATABILITY
The people who consume fish in Area 2 communities have clearly identified this as an issue that is
directly related to hydroelectric development. Based on the palatability studies conducted from
2002-2004, fish from Gull Lake, which is affected by hydroelectric development, currently receive the
DECEMBER 2015
5.6-16
lowest acceptability scores by members of TCN and FLCN compared to other study area lakes and AEA
offsetting lakes. However, the results of these studies were not statistically significant.
As illustrated in the pathways of effects diagram (Figure 5.6.1-1) the infestation rate for T. crassus in the
muscle of Lake Whitefish can be linked to hydroelectric development. Some of these links have been
established for waterbodies in other areas (e.g., SIL in Area 3; Section 5.6.4). Long-term data exist for
Split Lake, which has consistently been an export quality fishery. However, there are insufficient T.
crassus data from other Area 2 waterbodies to identify trends. There is currently no definitive link between
increased RI in Lake Whitefish and hydroelectric development for any Area 2 waterbodies.
DECEMBER 2015
5.6-17
5.6.4
Area 3: Southern Indian Lake to Split Lake Inlet
The upper portion of Area 3 is bounded on the upstream end by Leaf Rapids on the Churchill River and
extends through Opachuanau Lake and all of SIL with its outlets at the Missi Falls Control Structure (CS)
and the South Bay Diversion Channel (Map 5.6.4-1). Hydroelectric developments in the area include the
CRD and Wuskwatim GS. The CRD Route extends from the inlet of the South Bay Diversion Channel
downstream to First Rapids on the Burntwood River and includes the Missi Falls CS and Notigi CS. The
CRD caused major changes to the water regimes of several waterbodies in Area 3, in particular Southern
Indian and Notigi lakes. Wuskwatim GS caused some flooding of Wuskwatim Lake. Detailed information
regarding project descriptions for hydroelectric developments in Area 2 and their effects on the local
water regime can be found in Hydroelectric Development Project Description in the Region of Interest,
Part II Appendix 2F and Water Regime, Section 4.3.3.
5.6.4.1
PALATABILITY
The University of Manitoba was hired by North/South Consultants Inc. to conduct a taste-test study in
2002 (Ryland and Watts 2002a) at Nelson House. The researchers conducted a double blind taste test
using traditionally prepared fillets of Walleye, Northern Pike, and Lake Whitefish from Wuskwatim and
Footprint lakes that were affected by CRD and Leftrook and Baldock lakes that were not affected by CRD.
The taste test was conducted with 49 panellists from Nelson House. Samples of 30–40 g of freshly fried
(Walleye and Northern Pike) or boiled (Lake Whitefish) pieces of fish were assigned unique, three digit
random numbers and were evaluated by panellists for acceptability using a seven point category scale
(1 = dislike very much, 2 = dislike moderately, 3 = dislike slightly, 4 = neither like nor dislike, 5 = like
slightly, 6 = like moderately, 7 = like very much). Statistical analyses were conducted on the results.
in detail in Section 5.6.2.1.
Additional cyst count information was collected from SIL during recent fish community investigations
(Michaluk and Remnant 2012; Aiken and Remnant 2013; Aiken 2014). During these studies, Lake
Whitefish fillets were cut into approximately 1.0 cm transverse strips to expose all T. crassus cysts, which
were then enumerated. The sampling protocol for these studies was developed in conjunction with the
SIL Fishermen’s Association and Manitoba Conservation and Water Stewardship.
DECEMBER 2015
5.6-18
File Location: J:\MYP\MH_RCEA\Fish_Quality\PHASE_2\Mxd\20151205_RCEA_PhaseII_AE_FQ_EE_FishQualityAssessmentAreaSouthernIndianLakeToFirstRapidsRCEAArea3_cp.mxd
Created By: cparker - B Size Portrait BTB - MAR 2015
Churchill
Scale: 1:1,057,000
Hudson Bay
North
Knife
Lake
Thompson
Southern
Missi Falls
Control Structure
RCEA
Area 3
Indian
Lake
493
South Indian Lake
Opachuanau
Lake
Issett
Lake
Leaf Rapids
Karsakuwigamak
Lake
Pemichigamau
Lake
Mynarski
Lakes
Rat Lake
First Rapids
Macheewin
Lake
Osik L.
Notigi
Lake
280
391
od
wo
Notigi
Nisichawayasihk Cree Nation
Control
Nelson House (NAC)
Structure Wapisu
Lake
Threepoint urnt
B
Lake
Kinosaskaw
Wuskwatim
Lake
L.
er
Riv
Mystery am
g
L. ussi L.
p
A
Kelsey
G.S.
i
as
Thompson
Birch
Tree
Lake
6
Wuskwatim G.S.
NOTE: (NAC) Northern Affairs Community
Legend
Highway
Control Structure
Rail
DATA SOURCE:
Manitoba Hydro.
CREATED BY:
COORDINATE SYSTEM:
Assessment
0
0
10
20 Kilometres
10
20 Miles
DATE CREATED:
REVISION DATE:
22-OCT-15
05-DEC-15
VERSION NO:
QA/QC:
Southern Indian Lake to First Rapids
RCEA Area 3
1.0
Map 5.6.4-1
5.6.4.2
Residents of both South Indian Lake and Nelson House have expressed concerns regarding the taste
and texture of the fish harvested from impacted lakes after CRD, the Nisichawayasihk Cree Nation (NCN)
requested that the palatability of the fish be tested by an external agency. The University of Manitoba was
subsequently hired to conduct double blind taste tests (Ryland and Watts 2002b). The results of this
study are also discussed as part of the Wuskwatim Generation Project Environmental Impact Statement
(Manitoba Hydro and NCN 2003).
Lake Whitefish infestation rates with T. crassus cysts have been recorded during scientific investigations
in many northern Manitoba waterbodies since the 1950s, including some in Area 3 (e.g., McTavish 1952;
Sunde 1963a, b; Schlick 1966b) and records from the early 1960s have been summarized by Sunde
(1965a). Extensive information was also collected from SIL during the 1970s and 1980s from multiple
areas within the lake, including comparisons of infestation rates in dark and light coloured Lake Whitefish
(Watson and Dick 1979a, b; Bodaly et al. 1984; Johnston 1984; Peristy 1989). Much of the work
conducted in SIL tied increased cyst counts in Lake Whitefish with the downgraded quality of the Lake
Whitefish fishery (Bodaly et al. 1984). More recently, cyst counts were collected from small samples of
Lake Whitefish in Wuskwatim Lake as part of studies in support of the Wuskwatim Generation Project
Environmental Impact Statement (Manitoba Hydro and NCN 2003).
The FFMC routinely samples Lake Whitefish from Manitoba lakes with commercial fisheries (including at
least 12 lakes in Area 3) and counts cysts from dressed fish in their laboratory in Winnipeg. Fish are then
graded based on their RI.
5.6.4.3
The status and health of Lake Whitefish stocks in SIL were investigated from 2011-2013 as part of
Manitoba and Manitoba Hydro’s Coordinated Aquatic Monitoring Program and the SIL Environmental
Steering Committee studies. During these studies, cysts counts were collected from multiple areas in the
lake (Michaluk and Remnant 2012; Aiken and Remnant 2013; Aiken 2014) and an attempt was made to
distinguish between light and dark colour whitefish (Michaluk and Remnant 2012).
cysts from dressed fish in their laboratory in Winnipeg. Fish are then graded based on their RI. Current
(2015) Lake Whitefish grading results (unpubl. data) were obtained from 19 waterbodies in Area 3 for
comparison with earlier data, where applicable.
5.6.4.4
PALATABILITY
Both O-Pipon-Na-Piwin Cree Nation and NCN have stated that the taste and texture of the fish harvested
for domestic consumption declined after CRD. The decline in the quality was the subject of a domestic
fishing claim in South Indian Lake, which was settled with Manitoba Hydro in 1992. The reduced
DECEMBER 2015
5.6-20
palatability of the fish harvested for domestic purposes also was raised by NCN during the Wuskwatim
Generation Project environmental assessment. Due to concerns regarding the future palatability of fish in
Wuskwatim Lake following the construction of the Wuskwatim GS and the changes that NCN felt had
occurred as a result of CRD, a scientific study was requested by the First Nation to examine this.
The University of Manitoba was hired to conduct the study in 2002 (Ryland and Watts 2002b). Results
from this study, which was conducted in a scientific manner with all appropriate controls, found no
significant difference in the acceptability of fish among lakes for any species. However, following the
receipt of the report, some members of NCN stated that some of the panellists were not known to
consume large quantities of fish and that several other factors may have affected the results of the test
(S. Davies pers. comm.). The study did not resolve the issue of fish palatability for NCN.
The vast majority of historical information on T. crassus infestations in Area 3 waterbodies is from SIL
where there has been a significant commercial fishery since 1941 (Bodaly et al. 1984). Due to its size and
varying physical characteristics and uses between different regions of the lake, SIL has traditionally been
subdivided into seven distinct areas (Map 5.6.4-2). For the purposes of this document and to avoid
confusion when referring to the overall Area 3, which includes multiple lakes and rivers, areas within SIL
will be referred to as Historical Geographic Areas and identified as SIL Area 4, SIL Area 5 etc. Scientific
studies on the lake have generally sampled most of these areas, but the commercial fishery was
historically, before CRD, concentrated (approximately 99%) in SIL Area 4.
Prior to lake impoundment and CRD in 1976, the mean annual Lake Whitefish catch was 333,500 kg
(735,242 lbs) (see Fish Community, Section 5.3.6), most of which (greater than 99%) was graded as
light-coloured export quality fish that were only slightly parasitized by T. crassus (Figure 5.6.4-1). There
were differences in RI between areas of SIL, with Lake Whitefish captured in SIL Area 5, a relatively
shallow, inshore area of the lake populated primarily by dark variants of whitefish, typically more heavily
infested than fish from other areas of the lake. Fish from SIL Area 5 were rarely graded as export quality
and were avoided by the commercial fishery. Pre-1976, RI values from SIL Area 4 scientific studies and
commercial catches consistently graded the Lake Whitefish as export quality. Following impoundment,
commercial catches decreased to 115,000 kg (253,532 lbs) by 1982 largely due to a reduction in catchper-unit-effort (CPUE). Reduced catch-per-unit-effort was attributed to a redistribution of fish from SIL
Area 4 to other areas of SIL and to nearby waterbodies (Bodaly et al. 1984). Because some of these
areas (e.g., SIL Area 5) traditionally had lower grade Lake Whitefish, there was an overall increase in the
RI of T. crassus to more than 50 cysts/100 lbs dressed weight, downgrading the quality of the fishery from
export to other (identified as continental at the time). This increased RI persisted until at least the late
1980s (Figure 5.6.4-1). To maintain the economic viability of the fishery during this period, Manitoba
Hydro compensated for the difference in market value between continental and export grade Lake
Whitefish to the commercial fishers. In recent years, cyst counts from experimental studies (Michaluk and
Remnant 2012; Aiken and Remnant 2013; Aiken 2014) and commercial catches (FFMC unpubl. data)
have decreased and the FFMC has since returned the fishery to export status, though the productivity of
the fishery remains lower than historic values due to slow growth rates and other factors.
DECEMBER 2015
5.6-21
Recent FFMC grades for Lake Whitefish in other Area 3 lakes are presented in Table 5.6.4-1. Detailed
historical data for many of these lakes are not available for comparison, though little change in RI is
expected for those not directly affected by CRD unless there is a redistribution of fish from other areas
that have different RI values. For those with pre-CRD infestation data, Karsakuwigamak, Mynarski, Notigi,
and Opachuanau lakes have all been downgraded from export to other quality. All four of these lakes are
located between the Notigi and Missi Falls CSs and are affected, to varying degrees, by CRD. Though no
direct links have been identified, due to a general lack of scientific data from these lakes, it is possible
that effects from flooding (changes in copepod or Northern Pike abundance or redistribution of Lake
Whitefish) have altered the infestation rates. Lake Whitefish grades in Wapisu and Wuskwatim lakes have
not changed.
DECEMBER 2015
5.6-22
File Location: J:\MYP\MH_RCEA\Fish_Quality\PHASE_2\Mxd\20151205_RCEA_PhaseII_AE_FQ_EE_SouthernIndianLakeHistoricalGeographicAreas_cp.mxd
Churchill
Scale: 1:423,640
Hudson Bay
Thompson
SIL
Area 5
SIL
Area 4
Southern
Missi Falls
Control Structure
Strawberry
Island
SIL
Area 7
Long Point
SIL
Area 3
Indian
SIL
Area 2
SIL
Area 1
Lemay
Island
R
Lake
South Indian Lake
Opachuanau
Lake
South
Bay
SIL
Area 0
SIL
Area 6
Legend
493
Southern Indian Lake (SIL) Historical Geographic Area
Control Structure
Highway
DATA SOURCE:
Manitoba Hydro.
Southern Indian Lake
CREATED BY:
COORDINATE SYSTEM:
Assessment
0
0
5
10 Kilometers
4
8 Miles
DATE CREATED:
REVISION DATE:
22-OCT-15
05-DEC-15
VERSION NO:
QA/QC:
Historical Geographic Areas
1.0
Map 5.6.4-2
Thick gray line represents current FFMC export/other grade cut-off (50 cysts/100 lbs dressed weight).
Figure 5.6.4-1:
The Rate of Infestation of Triaenophorus crassus Cysts in Lake Whitefish from
Commercial Fishery and Experimental (SIL Areas 4 and 5 only) Catches in
Southern Indian Lake, 1952–2013
DECEMBER 2015
5.6-24
Table 5.6.4-1:
Waterbody
Pre-CRD
1,2
1976–1990
3
2006–2013
4,5
2015
5
Apussigamasi Lake
-
-
-
Other
Baldock Lake
-
-
Other
Other
Birch Tree Lake
-
-
-
Other
Burntwood River
-
-
Export
Export
Issett Lake
-
-
Export
Export
Export
-
Other
Other
Kinosaskaw Lake
-
-
-
Other
Leftrook Lake
-
-
-
Other
Macheewin Lake
-
-
Other
Other
Mynarski Lake
Export
-
-
Other
Mystery Lake
-
-
-
Other
Notigi Lake
Export
-
Other
Other
Opachuanau Lake
Export
-
Other
Other
Osik Lake
-
-
Other
Other
Pemichigamau Lake
-
-
-
Other
Rat Lake
-
-
Export
Export
Southern Indian Lake (all)
Export
Other
Export
Export
Southern Indian Lake (north
basin)
Export
Other
Export
Other
-
-
Export
Export
Wapisu Lake
Other
-
Other
Other
Wuskwatim Lake
Export
-
Export
Export
Karsakuwigamak Lake
Threepoint Lake
1.
2.
3.
4.
5.
Export = 0–40 cysts/100 lbs of fish (DFO) or 0–50 cysts/100 lbs of fish (FFMC); Other (includes Continental and Cutter
grades) = > 40 or > 50 cysts/100 lbs of fish (dressed weight).
Data sources: Bodaly et al. (1984); McTavish (1952); Schlick (1966b); Sunde (1963a, 1963b, 1965a).
Data sources: Bodaly et al. (1984); Peristy 1989.
Data sources: Michaluk and Remnant (2012); Aiken and Remnant (2013); Aiken (2014).
Data source: FFMC (unpubl. data).
DECEMBER 2015
5.6-25
5.6.4.5
Quality in Area 3
PALATABILITY
There is no scientific evidence to suggest that the taste, texture or palatability has been affected by
hydroelectric development in Area 3. However, the people who consume the fish in the communities have
clearly identified this as an issue that is directly related to hydroelectric development. The issue of
palatability remains unresolved.
muscle of Lake Whitefish can be linked to hydroelectric development and there is evidence linking
increased RI in SIL with the CRD. Specifically, the post-CRD redistribution of SIL fish from areas with low
RI (e.g., SIL Area 4) to areas with higher RI (e.g., SIL Area 5, other nearby lakes) increased the overall RI
in the commercial catch and resulted in the downgrading of the fishery. Watson and Dick (1979a)
predicted that an increase in copepods would result in an increase in T. crassus in Lake Whitefish in SIL.
However, there was a decrease in water temperature and an increase in turbidity associated with
impoundment and diversion, both of which were implicated in reduced zooplankton (including cyclopoid
copepods) abundance (Patalas and Salki 1984). Despite this decrease in abundance of copepods,
opportunities for infestation may have increased due to the redistribution of many Lake Whitefish to
shallower, inshore areas and possibly other waterbodies (Bodaly et al. 1984). Watson and Lawler (1965)
demonstrated that the most heavily infected C. bicuspidatus in Heming Lake, Manitoba were collected
from inshore areas, presumably near Northern Pike spawning habitat.
Although redistribution of fish appeared to be the primary linkage between increased cyst counts in the
SIL commercial fishery in the 1980s, an increase in Northern Pike, which often occurs with flooding
caused by hydroelectric development, may have also been a contributing factor. Increases in Northern
Pike were noted for young year classes immediately following impoundment in SIL (Bodaly and Lesack
1984). Increases in Northern Pike in shallow, flooded areas would increase the availability of early T.
crassus life cycle stages to copepods. There are no specific examples of this linkage in Area 3
waterbodies.
A small increase in zooplankton abundance may be expected in other waterbodies that experience
flooding from hydroelectric development in the absence of excessive turbidity or decreases in water
temperature. For example, it was predicted that an expected increase in retention time, volume and slight
nutrient enrichment of water in tributary waterbodies of Wuskwatim Lake (e.g., Sesep Lake, Wuskwatim
Lake south, Wuskwatim Brook) may result in a slight increase in zooplankton abundance
(Manitoba Hydro and NCN 2003).
The return of SIL to a mainly export grade fishery following several years of lower grades could be due to
several factors. One potential cause could be an increase in the proportion of Northern Pike captured in
the commercial fishery as Lake Whitefish catch-per-unit-effort decreased post-impoundment. Peristy
(1989) indicated that Northern Pike proportions in the commercial catch had increased relative to pre-
DECEMBER 2015
5.6-26
diversion, particularly in SIL Area 5, which consistently had the highest infestation rates in the lake. Most
of these Northern Pike were also captured in the spring, before spawning, which could be reducing the
number of mature T. crassus that are contributing to the parasite life cycle. Impacts of fishing pressures
on RI have been observed in other fish communities; for example, Amundsen and Kristoffersen (1990)
noted a dramatic reduction in T. crassus infestation rates in Powan (Coregonus lavaretus) following the
experimental reduction in population density of Northern Pike in a Norwegian lake. In addition, if cyclopoid
copepod abundance remained as low as observed shortly after impoundment (Patalas and Salki 1984),
this would further limit the rate of transmission between hosts. Unfortunately, recent zooplankton data
from SIL are not available for comparison. Commercial fishers may have also, over time, adapted to
target only the areas within SIL and other waterbodies where RI remained low, avoiding the more heavily
infested Lake Whitefish.
DECEMBER 2015
5.6-27
5.6.5
Area 4: Missi Falls Control Structure to Churchill
River Estuary
Area 4 comprises the reach of the Churchill River from the Missi Falls CS at SIL to the Churchill River
Estuary. Major waterbodies within this area include Northern Indian Lake, Fidler Lake, Billard Lake, and
the lower Churchill River (Map 5.6.5-1). Hydroelectric developments in the area include CRD and the
Lower Churchill River Water Level Enhancement Weir Project (Churchill Weir). The CRD, via the Missi
Falls CS, reduced flows in downstream waterbodies in the Churchill River system, particularly during
construction and staging periods. Construction of the Churchill Weir in 1998 increased upstream water
levels, mitigating some of the effects of CRD. Detailed information regarding project descriptions for
hydroelectric developments in Area 2 and their effects on the local water regime can be found in
Hydroelectric Development Project Description in the Region of Interest, Part II Appendix 2F and Water
Regime, Section 4.3.3.
5.6.5.1
PALATABILITY
There have been no palatability concerns raised in Area 4 waterbodies by local resource users and,
therefore, no associated studies.
in detail in Section 5.6.2.1. Non-commercial sampling for T. crassus infestations has not been conducted
in Area 4.
5.6.5.2
PALATABILITY
There is no published information describing the palatability of fish in Area 4 waterbodies either before or
after CRD or construction of the Churchill Weir.
There is historical information (primarily from the 1960s) on Lake Whitefish infestation rates with
T. crassus cysts from the Churchill River, Fidler Lake, Gauer Lake and, in particular, Northern Indian Lake
(Sunde 1965a; Anthony 1966).
DECEMBER 2015
5.6-28
Scale: 1:1,247,000
Churchill
Churchill River Weir
Assessment
HUDSON
BAY
Legend
Infrastructure
Control Structure
hil
lR
ive
r
Rail
hu
rc
C
RCEA
Area 4
Highway
Hudson Bay
Churchill
Partridge
Breast
Lake
Missi Falls
Control Structure
Thompson
Northern
Indian Lake
Fidler
Lake
Billard
Lake
Gauer
Lake
DATA SOURCE:
Province of Manitoba, Government of Canada, Manitoba Hydro.
CREATED BY:
COORDINATE SYSTEM:
0
10
20 Kilometres
DATE CREATED:
REVISION DATE:
06-OCT-15
07-DEC-15
VERSION NO:
QA/QC:
1.0
0
10
20 Miles
280
Missi Falls Control Structure to
RCEA Area 4
Map 5.6.5-1
5.6.5.3
cysts from dressed fish in their laboratory in Winnipeg. Fish are then graded based on their RI. Lake
Whitefish grading results (unpubl. data from 2011 and 2015) were obtained from the FFMC for the
Churchill River, Fidler Lake, Gauer Lake, Northern Indian Lake, Billard Lake, and Partridge Breast Lake
for comparison with earlier data, where possible (FFMC unpubl. data).
5.6.5.4
PALATABILITY
There has been no known information provided by resource users regarding decreased taste, texture,
and palatability specifically for Area 4. There is no published information on changes to palatability and
there is no scientific evidence to suggest that the taste, texture or palatability of fish has been affected by
hydroelectric development.
The majority of historical RI data were from Northern Indian Lake, though Fidler Lake, Gauer Lake, and
the Churchill River were also surveyed (Sunde 1965a; Anthony 1966). More recently, data have been
collected from at least six Area 4 waterbodies (FFMC unpubl. data; Table 5.6.5-1). Of all the sampled
waterbodies, only Partridge Breast Lake is currently graded as export quality, but there are no historical
data for comparison (FFMC unpubl. data). The Churchill River and Fidler and Northern Indian lakes were
graded as export quality during surveys in the 1960s, but have recently been downgraded to continental
or cutter (i.e., other) by FFMC. There is insufficient information to confirm any potential linkages to
hydroelectric development in Area 4. Gauer Lake has had consistently high cyst counts and has always
been graded as “other” (specifically cutter).
DECEMBER 2015
5.6-30
Table 5.6.5-1:
Waterbody
Pre-1980
Billard Lake
1,2
1980–1990
2006–2011
3
2015
3
-
-
-
Other
Churchill River
Export
-
-
Other
Fidler Lake
Export
-
Other
Other
Gauer Lake
Other
-
Other
Other
Export
-
-
Other
Partridge Breast Lake
-
-
-
Export
1.
2.
3.
Export = 0–50 cysts/100 lbs of fish (dressed weight); Other = > 50 cysts/100 lbs of fish (dressed weight).
Data from Sunde (1965a); Anthony (1966); and Topolinski (1972).
Data from FFMC (unpubl.).
5.6.5.5
Quality in Area 4
PALATABILITY
As noted above, there has been no known information provided by resource users regarding decreased
taste, texture, and palatability specifically for Area 4. There is no published information on changes in
palatability and there is no scientific evidence to suggest that the taste, texture or palatability of fish has
been affected by hydroelectric development.
muscle of Lake Whitefish can be linked to hydroelectric development. Some of these links have been
established for waterbodies in other areas (e.g., SIL in Area 3; Section 5.6.4). Long-term data exist for
Northern Indian Lake, which was consistently an export quality fishery until recently when it was
downgraded to continental (i.e., other). However, there are insufficient T. crassus data from other Area 4
waterbodies to identify trends. There is currently no definitive link between increased RI in Lake Whitefish
and hydroelectric development for any Area 4 waterbodies.
.
DECEMBER 2015
5.6-31
5.6.6
Summary of Effects of Hydroelectric Development
in the Region of Interest on Fish Quality
PALATABILITY
There are no known scientific linkages or pathways of effect between palatability and hydroelectric
development in the RCEA ROI. However, resource users in local communities continue to express
concerns about a decline in the quality of fish (in terms of taste, texture, and size) in waterbodies affected
by hydroelectric development, preferring the taste of fish from unaffected areas.
However, it should be noted that hydroelectric development can cause changes to fish diet, water quality,
water temperature, algae, and growth rates, all of which can, in turn, affect the taste and texture of fish.
These potential indirect linkages have not been subject to scientific studies in the RCEA ROI.
It should be noted that there are lakes affected by hydroelectric development to varying degrees
(e.g., Playgreen Lake, Split Lake, Wuskwatim Lake, to name a few) that have maintained a consistent
grade of commercial Lake Whitefish catches since before hydroelectric development, indicating that the
linkages may be weak in some waterbodies and that effects do not always occur. If a particular
hydroelectric development has only negligible effects to each of the three T. crassus life cycle hosts, then
effects on RI in Lake Whitefish should be similarly minimal.
Although some waterbodies appear to have remained unaffected, increased RI in Lake Whitefish has
been observed in several other RCEA ROI waterbodies affected by hydroelectric development with most
of the detailed data coming from studies conducted in SIL following CRD. The specific pathway(s) of
effect are not precisely known for most of the affected waterbodies and likely vary among them. For
example, redistribution of Lake Whitefish populations in SIL is thought to be at least one of the factors
that resulted in a decreased grade of the commercial catch in that lake following CRD. Changes to
copepod and/or Northern Pike host abundances and distributions that may be associated with flooding or
erosion during hydroelectric development may have also affected infestation rates in other waterbodies.
DECEMBER 2015
5.6-32
5.6.7
Bibliography
5.6.7.1
Aiken, J.K. 2014. Results of fish community investigations conducted in Southern Indian Lake, Manitoba,
2013. A report prepared for the Southern Indian Lake Commercial Fishermen’s Association by
Aiken, J.K. and Remnant, R.A. 2013. Results of fish community investigations conducted in Southern
Indian Lake, Manitoba, 2012. A report prepared for the Southern Indian Lake Commercial
Fishermen’s Association by North/South Consultants Inc., Winnipeg, MB. 128 pp.
Amundsen, P.A. and Kristoffersen, R. 1990. Infection of whitefish (Coregonus lavaretus L. s.l.) by
Triaenophorus crassus Forel (Cestoda: Pseudophyllidea): a case study in parasite control.
Canadian Journal of Zoology 68: 1187-1192.
Anthony, L. 1966. Northern Indian Lake Whitefish Infestation Test. Manitoba Department of Mines and
Natural Resources, Fisheries Branch. 4 pp.
Bodaly, R.A. and Lesack, L.F.W. 1984. Response of a boreal northern pike (Esox lucius) population to
lake impoundment: Wupaw Bay, Southern Indian Lake, Manitoba. Canadian Journal of Fisheries
and Aquatic Sciences 41: 706-714.
Bodaly, R.A., Johnson, T.W.D., Fudge, R.J.P., and Clayton, J.W. 1984. Collapse of the lake whitefish
(Coregonus clupeaformis) fishery in Southern Indian Lake, Manitoba, following lake irnpoundment
and river diversion. Canadian Journal of Fisheries and Aquatic Sciences 41: 692-700.
Davies, S., Baker, R., and Horne, B. 1998a. The quality of Lake Whitefish, Walleye, and Northern Pike
from Playgreen Lake, Little Playgreen Lake, and Mossy Bay (Lake Winnipeg). A report prepared
Davies, S., Baker, R., and Horne, B. 1998b. Fish movements, species composition, and catch data for
Playgreen Lake, Little Playgreen Lake, and Mossy Bay (Lake Winnipeg). A report prepared for
Izaguirre, G., Taylor, W.D. and Pasek, J. 1999. Off-flavor problems in two reservoirs, associated with
planktonic Pseudanabaena species. Water Science and Technology 40: 85-90.
Johnston, C.H. 1984. The genetic and environmental basis for external colouration in lake whitefish
(Coregonus clupeaformis (Mitchill)) from Southern Indian Lake, Manitoba. M. Sc. thesis, Faculty
of Graduate Studies, The University of British Columbia, Vancouver, BC. 132 pp.
Keeyask Hydropower Limited Partnership. 2012. Keeyask Generation Project Environmental Impact
Statement: Aquatic Environment Supporting Volume, Winnipeg, Manitoba. June 2012.
DECEMBER 2015
5.6-33
Lawler, G.H. 1955. Life history studies of Triaenophorus at Heming Lake, Manitoba. Part I. The life of T.
crassus and T. nodulosus in the final host, Esox lucius with special reference to changes in
infection rates from year to year. Fisheries Research Board of Canada, MS Report 604. 17 pp.
Lawler, G.H. and Scott, W.B. 1954. Notes on the geographical distribution and the hosts of the cestode
genus Triaenophorus in North America. Journal of the Fisheries Research Board of Canada 11:
884-893.
Lorio, W.J., Perschbacher, P.W., and Johnsen, P.B. 1992. Relationship between water quality,
phytoplankton community and off-flavors in channel catfish (Ictalurus punctatus) production
ponds. Aquaculture 106: 285-292.
Mackay, G.H., Davies, S., and Westdal, H. 1990. Post project assessment of Kelsey and Lake Winnipeg
Regulation impacts on Wabowden. The Wabowden Study Team, Winnipeg, MB. 98 pp.
Manitoba Hydro and NCN (Nisichawayasihk Cree Nation). 2003. Wuskwatim Generation Project
Environmental Impact Statement. Volume 5 Aquatic Environment.
McTavish, W.B. 1952. A biological survey of Southern Indian Lake. Report for the Manitoba Department
of Mines and Natural Resources.
Michaluk, Y. and Remnant, R.A. 2012. Results of fish community investigations conducted in Southern
Indian Lake, Manitoba, 2011. A report prepared for the Southern Indian Lake Commercial
Fishermen’s Association by North/South Consultants Inc., Winnipeg, MB. 105 pp.
Miller, R. B. 1952. A review of the Triaenophorus problem in Canadian lakes. Bulletin of the Fisheries
Research Board of Canada No. 95.
Moshenko, W.R. 1968. Whitefish infestation in Moose Nose Lake, Manitoba, in 1968. Department of
Mines and Natural Resources, Fisheries Branch. 3 pp.
NRG (Nelson River Group). 1986. Cross Lake environmental impact assessment study: Volume 3:
environmental impact statement. Nelson River Group, Winnipeg, MB. 54 pp.
Patalas, K. and Salki, A. 1984. Effects of impoundment and diversion on the crustacean plankton of
Southern Indian Lake. Canadian Journal of Fisheries and Aquatic Sciences 41: 613-637.
Peristy, D. 1989. A biological assessment of the post-impoundment commercial fishery at Southern
Indian Lake, Manitoba, with historical comparisons. M.N.R.M. practicum, Natural Resources
Institute, The University of Manitoba, Winnipeg, MB. 141 pp.
Persson, P.-E. 1980. Sensory properties and analysis of two muddy odour compounds, geosmin and 2methylisoborneol, in water and fish. Water Research 14: 1113-1118.
Pulkkinen, K., and Valtonen, E.T. 1999. Accumulation of plerocercoids of Triaenophorus crassus in the
second intermediate host Coregonus lavaretus and their effect on growth of the host. Journal of
Fish Biology 55: 115-126.
DECEMBER 2015
5.6-34
Ryland, D., and Watts, B. 2002a. Fish taste studies for York Factory First Nation. A report prepared for
Manitoba Hydro by the Department of Human Nutritional Sciences, University of Manitoba,
Ryland, D. and Watts, B. 2002b. Fish taste studies for Nisichawayasihk Cree Nation (NCN). Final Report
(Reference File /70.01.412.2), Department of Human Nutritional Sciences, University of
Manitoba, 28 pp.
Ryland, D., and Watts, B. 2004a. Fish taste studies for Tataskweyak Cree Nation. A report prepared for
Ryland, D., and Watts, B. 2004b. Fish taste studies for Fox Lake Cree Nation. A report prepared for
Schlick, R.O. 1966a. Whitefish infestation test, Sipiwesk Lake, 1966. Manitoba Department of Mines and
Natural Resources, Fisheries Branch. 5 pp.
Schlick, R.O. 1966b. Whitefish infestation test, Wuskwatim Lake, August 1966. Manitoba Department of
Mines and Natural Resources, Fisheries Branch. 6 pp.
Schlick, R.O. 1967. Whitefish infestation Split Lake, 1966. Manitoba Department of Mines and Natural
Resources, Fisheries Branch. 3 pp.
Schlick, R.O. 1979. A fisheries survey of Waskaiowaka Lake, 1972. MS Report No. 79-61, Manitoba
Department of Mines, Natural Resources and Environment, Research Branch. 29 pp.
Schrader, K.K. and Blevins, W.T. 1993. Geosmin-producing species of Streptomyces and Lyngbya from
aquaculture ponds. Canadian Journal of Microbiology 39: 834-840.
Sowe, M.S. 1986. The coregonid and pike fishery in Manitoba: factors influencing abundance of
Triaenophorus crassus Forel in Lake Whitefish (Coregonus clupeaformis Mitchill) in commercially
fished lakes. . M. Sc. thesis, Department of Zoology, The University of Manitoba, Winnipeg, MB.
243 pp.
Split Lake Cree – Manitoba Hydro Joint Study Group. 1996a. Analysis of change: Split Lake Cree Post
Project Environmental Review. Split Lake Cree – Manitoba Hydro Joint Study Group; vol. 1 of 5.
Split Lake Cree – Manitoba Hydro Joint Study Group. 1996b. History and first order effects: Manitoba
Hydro projects - Split Lake Cree Post Project Environmental Review. Split Lake Cree – Manitoba
Hydro Joint Study Group; vol. 2 of 5.
Split Lake Cree – Manitoba Hydro Joint Study Group. 1996c. Environmental matrices: Summary of
Manitoba Hydro impacts - Split Lake Cree Post Project Environmental Review. Support from
William Kennedy Consultants Ltd. & InterGroup Consultants Ltd. Split Lake Cree - Manitoba
Hydro Joint Study Group; vol. 3 of 5.
DECEMBER 2015
5.6-35
Sunde, L.A. 1963a. South Indian Lake whitefish infestation test, March 5 to 7, 1963. Manitoba
Department of Mines and Natural Resources, Fisheries Branch MS Report.
Sunde, L.A. 1963b. Summary of whitefish infestation tests conducted in Northern Manitoba in 1963.
Manitoba Department of Mines and Natural Resources, Fisheries Branch. 2 pp.
Sunde, L.A. 1964. Walker Lake whitefish infestation test. Manitoba Department of Mines and Natural
Resources, Fisheries Branch MS Report. 12 pp.
Sunde, L.A. 1965a. Summary of department of fisheries whitefish infestation tests for northern Manitoba
August 1962 to February 1965. Manitoba Department of Mines and Natural Resources, Fisheries
Branch. 4 pp.
Sunde, L.A. 1965b. Summary of whitefish infestation tests conducted in northern Manitoba in 1964.
Manitoba Department of Mines and Natural Resources, Fisheries Branch. 2 pp.
Topolinski, D. 1972. The Ilford fisherman’s cooperative: A case study in the commercial fisheries of
northern Manitoba. M.N.R.M. practicum, Natural Resource Institute, University of Manitoba,
Watson, N.H.F. and Lawler, G.H. 1965. Natural infections of cyclopid copepods with procercoids of
Triaenophorus spp. Journal of the Fisheries Research Board of Canada 22: 1335-1343.
Watson R.A. and Dick. T.A. 1979a. Metazoan parasites of whitefish Coregonus clupeaformis (Mitchill)
and cisco C. artedi Lesueur from Southern Indian Lake, Manitoba. Journal of Fish Biology 15:
579-587.
Watson R.A. and Dick. T.A. 1979b. Metazoan parasites of pike, Esox lucius Linnaeus, from Southern
Indian Lake, Manitoba, Canada. Journal of Fish Biology 17: 255-261.
Yurkowski, M. and Tabachek, J.-A.L. 1980. Geosmin and 2-methylisoborneol implicated as a cause of
muddy odor and flavor in commercial fish from Cedar Lake, Manitoba. Canadian Journal of
Fisheries and Aquatic Sciences 37: 1449-1450.
5.6.7.2
Personal Communications
Davies, Stuart. 2015. Senior Biologist. North/South Consultants Inc. Email correspondence with Michael
Johnson, North/South Consultants Inc., Winnipeg MB, October 20, 2015.
DECEMBER 2015
5.6-36
WATER – SEALS
5.7
Seals
5.7.1
Introduction
Both harbour (Phoca vitulina) and bearded (Erignathus barbatus) seals are year-round residents of
Hudson Bay, with patchy distributions in circumpolar areas as far north as 85°N (Burns 1981; Sergeant
1986). The ringed seal is the most common seal species in Hudson Bay (Smith 1975; Sergeant 1986);
however, this species is heavily dependent on sea ice year-round and is uncommon in both the Nelson
and Churchill River areas. Consequently, ringed seals were not considered further. While harbour seals
are more common to the Churchill River and estuary (Remnant 1997; Bernhardt 1999, 2000, 2001, 2003,
2006), bearded seals predominate in the Nelson River area (Baker 1989, 1990; Bernhardt 2014).
The global bearded seal population is estimated to be more than 500,000 animals (Riedman 1990) and is
listed as “Least Concern” on the International Union for Conservation of Nature (IUCN) and Natural
Resources Red List of Threatened Species (IUCN 2014). Bearded seals occur in low densities throughout
the Canadian Arctic (Mansfield 1967; Burns 1981; Cleator 1996; Lunn et al. 1997) and while discrete
populations have not been delineated (Cleator 1996; Kovacs 2002), geographical variation in
vocalizations suggests some population substructure (Risch et al. 2007). The number of bearded seals in
Canadian waters is unknown (Cleator 1996; Kovacs 2002); however, Cleator (1996) estimated a
minimum of 190,000 animals. The population is considered stable, as hunters in the Arctic have not
reported declines in bearded seal numbers while maintaining consistent hunting levels. Canadian
populations are not listed under the Species at Risk Act and are listed as “Data Deficient” by the
Committee on the Status of Endangered Wildlife in Canada (COSEWIC) (2015). Small numbers of
bearded seals occupy the Churchill and Nelson River mouths during the open-water season (e.g.,
Remnant 1997; Bernhardt 1999, 2000, 2001, 2006).
Global estimates for harbour seals vary. Fisheries and Oceans Canada (DFO) (2015) estimated the
global population to be 5–6 million individuals, while a previous study conducted by IUCN (2008)
estimated the total number to be closer to 350,000–500,000. Harbour seals are not listed under the
Convention on International Trade in Endangered Species of Wild Fauna and Flora, and the IUCN has
designated the species as “Least Concern” due to its large and either stable or increasing global
population. Despite this stability, IUCN (2008) recommended that local populations required further
assessment due to small and/or declining numbers in some areas. Estimates of harbour seal numbers in
Canadian waters are not available (e.g., Baird 2001; Remnant 1997). Harbour seals prefer ice-free areas
(Burns 2002) in shallower waters less than 50 m in depth (Tollit et al. 1997; Lesage et al. 2004;
Bajzak et al. 2012). This species commonly occurs in the nearshore freshwater areas of the Churchill
River estuary (Remnant 1997; Bernhardt 1999, 2000).
5.7.1.1
Pathways of Effect
Due to the small amount of data relating to seals in the Churchill and Nelson River areas, pathways of
effect were developed using information from both the study area and adjacent regions. Habitat
DECEMBER 2015
5.7-1
WATER – SEALS
alterations may affect seals directly in the form of physiological and behavioural changes, or indirectly
through ecological processes (e.g., trophic linkages; Figure 5.7.1-1). Water temperature, salinity, depth,
flow and sedimentation rates are influenced by discharge and when combined with natural processes
(e.g., tidal cycle), can alter the suitability of estuarine habitats (Lawrence et al. 1992). For example,
increased river flow during the flood tide can decrease the availability of haul-out sites used by seals.
Hauling out is the most commonly observed seal behaviour in the Churchill and Nelson River areas;
however, the purpose of this behaviour is poorly understood. Seals may haul out for a number of reasons,
including: pupping (Mansfield 1967); skin cell maintenance (Feltz and Fay 1966), sleep (Schneider et al.
1980; Remnant 1997), predator avoidance (Terhune 1985), mate selection (Renouf and Lawson 1986),
thermoregulatory advantage (Watts 1992; Remnant 1997; Bernhardt 2006); and social interaction
(Remnant 1997). Consequently, alterations in the quality or quantity of haul-out areas may have
implications to seals.
Indirect impacts of hydroelectric development focus primarily on trophic linkages. Bearded and harbour
seals are largely opportunistic feeders, ingesting a variety of (mostly benthic) fish and invertebrates
(Antonelis et al. 1994; Bjørge et al. 1995; Tollit et al. 1997; Lesage et al. 1999; Gjertz et al. 2001;
Hastings et al. 2004; Bajzak et al. 2012). Evidence suggests that estuaries may be important feeding
areas for seals (e.g., Lowry et al. 1980; Finley and Evans 1983; Antonelis et al. 1994; Remnant 1997;
Hjelset et al. 1999; Dehn et al. 2007); however, harbour seals near Churchill appear to depend less on
these areas for foraging (Remnant 1997; Bajzak et al. 2012). Although mercury-related studies linked to
dietary preferences have been conducted for seals in Hudson Bay (e.g., Young et al. 2009), research
directly pertaining to seals in the Churchill and Nelson rivers were unavailable.
Noise and other types of disturbance may cause a variety of behavioural responses in seals, including:
increased vigilance; changes in foraging behaviour; increased energy demand; avoidance; changes in
habitat use (including haul-out behaviour); decreased reproductive success (e.g., changes in lair
attendance, nursing bouts, reproductive output); and individual survival (Allen et al. 1984; Kovacs and
Innes 1990; Lidgard 1996; Barton et al. 1998; Shaughnessy et al. 1999; Henry and Hammill 2001; Edrén
et al. 2004; Kucey 2005; Orsini et al. 2006). Responses appear to vary with species, reproductive state,
and distance or type of noise produced. In most cases, the closer the disturbance, the more likely seals
are to enter the water (e.g., Allen et al. 1984; Brown and Prior 1998; Suryan and Harvey 1999; Henry and
Hammill 2001; Johnson and Acevedo 2007; Fox 2008; Jansen et al. 2010). Henry and Hamill (2001)
found that reproductive and moulting states influenced behaviour when exposed to disturbance, with
seals less likely to enter the water during moulting, and more readily entering the water during the
pupping season.
DECEMBER 2015
5.7-2
WATER – SEALS
Arrow width is not an indication of magnitude.
Figure 5.7.1-1:
DECEMBER 2015
Linkage Diagram Showing Potential Pathways of Effect of Hydroelectric Development and Other Factors on Seals
5.7-3
WATER – SEALS
Other drivers, both historic and current, not related to hydroelectric development have the potential to
influence seal use of the Churchill and Nelson River estuaries. Key drivers include (Figure 5.7.1-1):
•
harvesting;
•
Port of Churchill (construction and operation);
•
•
shipping;
•
research (e.g., rocket launching facilities out of Churchill).
military activities (e.g., air traffic, training exercises); and
The existence of multiple pathways makes distinguishing hydroelectric-related effects from other drivers a
difficult task. For example, the Port of Churchill, completed in 1931, may have affected haul-out locations
along the eastern shoreline of the Churchill River estuary. Ongoing maintenance activities also may affect
seal use of the estuary.
Due to the lack of physiological and ecological information for seals within the RCEA Region of Interest
(ROI), determining the magnitude of potential impacts from hydro-related and other anthropogenic
activities is not possible.
5.7.1.2
Indicators and Metrics
Indicators and metrics used to assess potential effects to seals were constrained by the amount of
existing data specific to the study areas. For the purposes of the Phase II report, species abundance and
distribution were combined into one indicator used to describe seal communities and to discuss potential
impacts of hydroelectric development.
5.7.1.3
The approach used to evaluate the potential effects of hydroelectric development on seals involved
collecting and presenting all available information within the given area for pre- and post-hydroelectric
development time periods.
5.7.1.4
Data Limitations
The following describes the data limitations for seals in areas 2 and 4 that affect the ability to conduct a
more comprehensive review. These limitations include:
•
A lack of quantitative pre- and post-hydroelectric development data, which precludes a determination
of hydroelectric development effects on seal populations in the RCEA ROI.
•
Information on behaviour and habitat use in the context of climate change is limited. Long-term data
sets examining the influence of climate change on seals, particularly as it relates to hydroelectric
development, are lacking.
DECEMBER 2015
5.7-4
WATER – SEALS
5.7.2
Area 2: Kelsey Generating Station to the Nelson
River Estuary
For the purposes of this section, the Nelson River estuary is defined as the extent of the Nelson River
between Gillam Island (the upstream extent of tidal influence) up to, and including, the freshwatersaltwater mixing zone (or “mixing zone”), the area where freshwater from the Nelson and Hayes rivers
mixes with marine waters of Hudson Bay. The location and size of the mixing zone is dependent on
several factors (Nelson River flow, tide state, wind and wave action, oceanographic currents); however, at
its maximum, the zone begins approximately 5 km downstream of Port Nelson and may extend more than
20 km into Hudson Bay (Map 5.7.2-1).
In this assessment, 1976 (operation of the Lake Winnipeg Regulation [LWR] and Churchill River
Diversion [CRD]) was selected as the beginning of effects to seals as a result of hydroelectric
development due to the potential for alterations in shoreline habitat and effects to seal use of the river and
estuary.
5.7.2.1
Information on seal use of the lower Nelson River and estuary prior to hydroelectric development is
limited to opportunistic observations from the 1970s (Didiuk 1975). Post-hydroelectric development
studies include multi-year pre- and post-Limestone Generating Station (GS) environmental monitoring
programs conducted by Manitoba Hydro (Baker 1989, 1990; North/South Consultants Inc. 2012) and
studies conducted in support of preparation of an Environmental Impact Statement (EIS) for the potential
Conawapa Generation Project (GP) (Ambrose and Berger 2012a, b; Bernhardt 2014). Additional
information included broader investigations of Hudson Bay populations (e.g., Lunn et al. 1997; Bajzak et
al. 2012), and research focused on seals in the context of climate change (e.g., Stewart and Lockhart
2005).
5.7.2.2
No additional analyses were conducted for Area 2 seals.
5.7.2.3
Changes in Seals over Time
The following discussion was based on qualitative and quantitative data presented in key published
literature.
DECEMBER 2015
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Minimum extent of the mixing zone
Maximum extent of the mixing zone
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DATA SOURCE:
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Map 5.7.2-1
WATER – SEALS
5.7.2.3.1
Pre-Hydroelectric Development
Historical information related to seals in the Nelson River and estuary is limited to anecdotal observations
from the early 1900s noting the presence of seals in the estuary (Comeau 1915), and opportunistic
observations from a 1974/75 Provincial wildlife assessment (Didiuk 1975). Didiuk (1975) observed
bearded, harbour and ringed seals in the area spanning Kettle GS to the estuary. Although one seal
(species unknown) was reported on Seal Island (Map 5.7.2-2), no further information was provided.
Domestic seal harvests were relatively infrequent in the York region during the 1600s and 1700s (Reeves
and Mitchell 1989). Seal meat was primarily used as dog food (Fast and Saunders 1996) and oil was sold
to the Hudson’s Bay Company (Lytwyn 2002).
5.7.2.3.2
Post-Hydroelectric Development
In 1988, Manitoba Hydro initiated a multidisciplinary study of the Nelson River estuary to collect baseline
data prior to completion of the Limestone GS. As part of that study, Baker (1989, 1990) found that
bearded seals were often the only seal species present in the estuary and were most abundant during
late summer and fall. In that study, bearded seals occurred in groups of up to six individuals as far
upstream as Ship Island.
Bernhardt (2014) also found that, with the exception of a few harbour seals, all seals observed in the
Nelson River estuary between 2003 and 2009 were bearded seals. Within the lower Nelson River, seals
concentrated their activity in the immediate vicinities of Gillam Island and Port Nelson, hauling out on the
shores of islands, small reefs and shoals, and on exposed tidal flats around the piers of Port Nelson.
Time of year was an important determinant of seal haul-out activity during those years (Figure 5.7.2-1),
while other factors such as time of day, weather conditions (e.g., air temperature, wind speed), river
discharge, and tide state also played a role. No direct linkages were found between tide state and seal
numbers between Gillam Island and Port Nelson; however, tide state appeared to influence the number of
seals hauled out at Port Nelson. Few seals occurred upstream of Deer Island and only one seal was
observed near the potential Conawapa GP site (Map 5.7.2-2; Bernhardt 2014).
Seals are occasionally reported along the entire reach of the lower Nelson River up to the Limestone GS
tailrace (Bernhardt 2014). Group size in haul-out areas was larger in 2006 and 2007 than reported
previously (i.e., Baker 1989, 1990); however, considerably fewer seals were observed during the 2009
surveys conducted during similar time periods (Bernhardt 2014). Although lower seal numbers in 2009
may have been associated with higher Nelson River flow, Bernhardt (2014) concluded that factors other
than flow likely contributed as higher seal numbers were observed under similar conditions in 2007.
Based on the small number of seals observed upstream of Gillam Island, and given published dietary
information (e.g., Smith 1981), Bernhardt (2014) suggested that most foraging likely occurs in the estuary
and coastal offshore areas rather than in the river itself.
Seals are rarely harvested in the Nelson River area due to the reduced numbers of people in the York
Factory area (Lower Nelson Overview Study Team 1981) and the decline of commercial sealing in
Hudson Bay (Stewart and Lockhart 2005). A resource use study conducted in 1995 reported that hunters
DECEMBER 2015
5.7-7
WATER – SEALS
accessing the Nelson River by way of the Conawapa Access Road harvested two seals (MacDonell
1996). However, use of the access road for the purposes of seal harvesting is rare (MacDonell 1996).
Determining the impacts of hydroelectric development on seals in the Nelson River area is not possible
without the appropriate historical data. However, Bernhardt (2014) reasoned that although meteorological
factors may affect seal haul-out activity over short time periods, hydrological factors may have longerterm impacts. Bernhardt’s (2014) results suggest that Nelson River discharge, in addition to date, air
temperature, and wind speed, may affect the number of seals in the lower-most portion of the Nelson
River (i.e., between Gillam Island and Port Nelson). Increased Nelson River discharge and subsequent
changes to water level may negatively affect seal use of this reach by altering the availability of suitable
haul-out locations.
Determination of cumulative impacts related to hydroelectric development are further complicated by the
lack of long-term climate change data associated with seal behaviour and habitat use both within, and
outside of, the RCEA ROI.
Source: Bernhardt 2014.
Figure 5.7.2-1:
Seasonal Differences in the Number of Seals Observed during Systematic
Surveys in 2006 and 2007 between the Upstream End of Gillam Island to Port
Nelson in Relation to Tide State, Compared with Opportunistic Observations
Conducted at Low Tide in 2009
DECEMBER 2015
5.7-8
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Ship
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Seal Count
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Distribution of Seal
Haul-out Sites
Nelson and Hayes Rivers 2006 and 2007
20 - 35
Map 5.7.2-2
WATER – SEALS
5.7.2.4
Cumulative Effects of Hydroelectric Development on Seals
in Area 2
5.7.2.4.1
Summary
•
Bearded seals are the predominant seal species in the Nelson River and estuary. The impacts of past
hydroelectric development to seals in this region cannot be determined due to lack of both current
and historical data. Based on behaviour and habitat use, hydroelectric impacts to seals may have
been related to displacement of haul-out sites in the lower portion of the river in areas of increased
discharge above the zone of tidal influence.
•
Although group size in haul-out areas appeared to decrease during periods of higher Nelson River
flow (e.g., 2009), factors other than flow (time of year/day, weather conditions, tide state) also affect
seal use of the river and estuary.
DECEMBER 2015
5.7-10
WATER – SEALS
5.7.3
Area 4: Missi Falls Control Structure to the
For the purposes of this section, the Churchill River estuary is defined as the area from Mosquito Point to
the mouth of the Churchill River between Cape Merry and Fort Prince of Wales (Map 5.7.3-1). As in
Area 2, 1976 (operation of LWR and CRD) was selected as the beginning of effects to seals in this region
as a result of hydroelectric development.
Activities (both past and present) not related to hydroelectric development also may influence seal use of
the Churchill River and estuary. In addition to harvesting, these include military and research activities,
construction and operation of the Port of Churchill (including dredging), and associated shipping activities.
In 1942, the United States Air Force began construction of a military base approximately 8 km southeast
of the Town of Churchill (Brandson 2011). The base was completed in 1945, and became the Joint
Services Experimental Station in 1946, facilitating operations of the Royal Canadian Air Force, United
States Air Force, Defence Research Northern Laboratory, Department of Transport, and Royal Canadian
Navy. In 1964, the United States forces discontinued their presence at Fort Churchill and control of the
base by the Canadian military ended. However, operation of the base continued under the Department of
Public Works and Canadian military exercises (including aerial, boat- and land-based activities) continued
until 1980 (Brandson 2011).
In 1957, a rocket launching facility was established in Churchill by the United States Special Committee
for the International Geophysical year of 1957/58 (Brandson 2011). The Fort Churchill Rocket Facility
(later re-named the Churchill Research Range) utilized a payload recovery area that spanned
2
approximately 700,000 km of land and water (Brandson 2011). The last rocket was launched at the
facility in 1988 (The Manitoba Historical Society 2015a).
Construction for the Port of Churchill began in the 1920s and was completed in 1931. The port maintains
a 140,000-tonne elevator and four berths for the loading and unloading of grain, general cargo, and
tanker vessels (The Manitoba Historical Society 2015b). Maintenance activities for port infrastructure
(e.g., stabilization) and accessibility have been ongoing since the 1930s (Pratte 1976; Idle 1989),
although dredging activities were last performed in the mid- to late 1990s (Omnitrax 2001a, cited in
Stewart and Howland 2009). Shipping to and from the port continues throughout the open-water season.
The degree to which anthropogenic activities other than hydroelectric development may have influenced
seals in the Churchill River area is unknown as environmental assessments were not available.
5.7.3.1
Historical information pertaining to seal use of the lower Churchill River and estuary is limited to a 1954
study comparing seal diets throughout the eastern Canadian Arctic (McLaren 1958a), and estimates of
bearded seal populations in the Canadian Arctic through observations and harvest data (McLaren 1958b).
DECEMBER 2015
5.7-11
WATER – SEALS
Information specific to the study area after 1976 included:
•
surveys conducted by Manitoba Hydro in support of EIS preparation for the Lower Churchill River
Water Level Enhancement Weir Project (Remnant 1997; Manitoba Hydro and Town of Churchill
1997);
•
post-weir environmental monitoring (Bernhardt 1999, 2000, 2001, 2003, 2006; Bernhardt and Holm
2007), and
•
current information regarding harbour seal abundance and distribution in the Churchill River estuary
in 2013 and 2014 (Florko 2015).
Additional resources include status reports (e.g., Baird 2001; COSEWIC 2007) and population
assessments (e.g., Lunn et al. 1997; DFO 2011), as well as biological and ecological investigations in the
context of climate change (Stewart and Lockhart 2005; Bajzak et al. 2012).
5.7.3.2
No additional analyses were conducted for Area 4 seals.
5.7.3.3
Changes in Seals over Time
The following discussion was based on qualitative and quantitative data presented in key published
literature.
5.7.3.3.1
Pre-Hydroelectric Development
Seal use of the Churchill River and estuary prior to CRD and other hydroelectric developments is poorly
documented. McLaren (1958b) observed small numbers of ringed and bearded seals near Churchill, MB
in the early 1950s, while McLaren (1958a) reported benthic invertebrates such as decapods
(e.g., Hippolytidae, Eualus sp., Lebbeus sp.), amphipods (e.g., Lysianassidae), and small fish
(e.g., Cottidae) from the stomachs of two ringed seals captured in the Churchill area in 1954
(McLaren 1958a). In the years leading up to CRD, Churchill residents harvested a small number of seals
for bait and dog food, primarily in the fall (Manitoba Department of Mines and Natural Resources
[MDMNR] 1955, 1956; McRae and Remnant 1997).
5.7.3.3.2
Post-Hydroelectric Development
No pre-CRD quantitative data are available to make pre- and post-CRD comparisons of seal distribution
and abundance in the lower Churchill River and estuary. However, of the 20 long-term Churchill residents
interviewed in Edye-Rowntree (2006), one (Mr. Chris Campbell) noted that “There are more seals around
the river than before…” suggesting that seals may have been more abundant along the lower Churchill
River than in pre-CRD years in response to decreasing water levels. In support of the Lower Churchill
River Water Level Enhancement Weir Project, Manitoba Hydro and the Town of Churchill (1997)
conducted detailed seal surveys in 1996 and 1997. Based on the 1996/97 data, and incidental
observations collected in 1994 and 1995, the authors reported that seals were typically present in the
estuary by mid-June, with increased numbers in early summer and fall (late August-September). The
DECEMBER 2015
5.7-12
WATER – SEALS
largest number of seals observed at one time in the haul-out area, located near the west bank of the river
between Drachm and Mosquito points (Map 5.7.3-1), was 32. Harbour seals were the most commonly
observed species, although juvenile bearded seals were occasionally present. Remnant (1997) reported
that climatic factors could influence seal use of the estuary, reporting that strong northerly winds, in
combination with rain and low air temperatures, appeared to reduce seal use of the haul-out site. High air
temperatures (greater than 25°C) also appeared to reduce numbers at the haul out area (Remnant 1997;
Bernhardt 2001; Watts 1992).
Potential uses for the main haul-out area included social interaction, thermoregulatory advantage and rest
(Manitoba Hydro and the Town of Churchill 1997; Remnant 1997), while an area 750 m upstream was
likely used opportunistically for feeding (Remnant 1997). Although pupping was not observed in the
vicinity of the weir axis, the presence of seal pups in fall suggested that pupping occurred in the region.
Pupping was documented in the area during 2013 and 2014 (Florko 2015). Most seals appear to spend
the majority of their time resting at the haul-out area (Bernhardt 2006).
Seal responses to construction and operation of the Lower Churchill River Water Level Enhancement
Weir Project were assessed by Bernhardt (1999, 2000, 2001, 2006) and summarized in Bernhardt and
Holm (2007). In all years (i.e., before and after weir construction), seal numbers in the lower Churchill
River fluctuated daily and, to a lesser extent, seasonally. Seals were observed from the Port of Churchill
to as far as 22 km upstream of the weir axis prior to construction, with more concentrated numbers along
the main haul-out site (Bernhardt 1999; Map 5.7.3-1). Although seal abundance and distribution did not
change during construction, the animals were ultimately displaced from the main haul-out area in
response to elevated water levels upstream of the weir (Manitoba Hydro and the Town of Churchill 1997).
As water levels increased, seals began hauling out farther upstream (approximately 500 m), before
eventually settling in downstream locations between the weir and Mosquito Point (Figure 5.7.3-1;
Bernhardt 1999).
No seasonal or daily trends in seal numbers were observed at post-weir haul-out sites (Bernhardt 2006).
Meteorological factors (wind speed, air temperature and cloud cover) also did not appear to affect seal
numbers, but river discharge and water elevation downstream of the weir had significant negative effects
on seal abundance during extreme high flows. Although not significant, tide state also appeared to affect
seal numbers in some portions of the haul-out area. Fewer harbour seals were present in 2005 when
Churchill River discharge was exceptionally high (2,500 cms) (Table 5.7.3-1; Bernhardt 2006). During that
period, seals were restricted to hauling out on the few exposed boulders occurring along the river bank
due to the inundation of haul-out sites (Bernhardt 2006). Seals were occasionally observed upstream of
the weir, confirming that the structure did not limit movements along the river (Bernhardt 2001, 2003,
2006). However, the number of seals observed upstream of the weir was lower in post-project years.
More recent seal surveys suggest that the number of harbour seals using the Churchill River has
increased dramatically since 2005 (Florko 2015). As many as 110 seals were observed at one time during
June 2014 (Florko 2015). Continued use of the lower Churchill River by seals suggests that this area
remains a suitable, and likely preferable, haul-out location for harbour seals (Bernhardt 2006). It is
unclear whether the voluntary moratorium placed on seal harvests in the late 1990s (discussed below), or
the discontinuation of seal harvests for the purposes of bear baiting contributed to this increase.
DECEMBER 2015
5.7-13
File Location: J:\MYP\MH_RCEA\Marine_Mammals\PHASE_2\MXDs\20151201_RCEA_PhaseII_AE_MarineMammals_DistributionOfSealHauloutSitesLowerChurchillRiver_cp.mxd
Scale: 1:85,000
Hudson Bay
Churchill
Hudson
Bay
Thompson
Prince of Wales Fort
Cape Merry
Churchill
Churchill
River
Mosquito Point
Primary Haul-out Site
Weir Axis
Drachm Point
Chu
r
chi
ll
Rive
r
Goose
Creek
Warkworth
Lake
Legend
Pre-Weir Haul-Out Site
Post-Weir Haul-Out Site
Churchill River Weir Axis
DATA SOURCE:
Government of Canada, North/South Consultants, Manitoba Hydro
Distribution of Seal Haul-out Sites
CREATED BY:
Lower Churchill River
COORDINATE SYSTEM:
Assessment
0
0
1
2 Kilometres
0.75
1.5 Miles
DATE CREATED:
REVISION DATE:
27-JUL-15
01-DEC-15
VERSION NO:
QA/QC:
2.0
Map 5.7.3-1
WATER – SEALS
Source: Bernhardt 1999.
Zone 1 includes the area from the downstream face of the weir extending downstream into and including the Churchill River.
Zone 2 includes the area between Drachm Point downstream to the weir.
Zone 3 includes the lower Churchill River upstream of Drachm Point.
Figure 5.7.3-1:
Distribution of Seals Observed during Aerial Surveys of the Lower Churchill
River, 1998
The small number of seals observed upstream, combined with seal movements north into the estuary,
indicate that seals primarily forage downstream of the weir and/or in nearshore marine areas (Bernhardt
2001, 2003, 2006). Bajzak et al. (2012) used satellite-linked radio transmitters to track movements and
dive behaviour of Churchill area harbour seals (Figure 5.7.3-2), reporting that seals conducted repeated
trips between nearshore Hudson Bay and the Churchill River haul-out area in spring and fall, with
frequent offshore trips. Offshore trips were presumed to be for feeding (Bernhardt 2006), which is
consistent with harbour seal foraging behaviour observed in other locations (e.g., Lesage 1999;
Lowry et al. 2001; Dietz et al. 2003). Harbour seals from the Churchill River showed a high degree of
seasonal fidelity to the area, and to specific offshore areas (Bajzak et al. 2012).
Manitoba Hydro and the Town of Churchill (1997) predicted that increased harvest pressure as a result of
weir construction would be the largest impact to seals. A voluntary moratorium on seal harvests in the
vicinity of the weir was put into place and few seals were harvested in the area in post-weir years
(Bernhardt 2003). The shallow water, high water velocity and an abundance of large boulders
downstream of the weir prevented whale watching and other boat traffic from approaching hauled-out
seals. Bernhardt (2003) reported that few people were observed near the current haul-out areas.
DECEMBER 2015
5.7-15
WATER – SEALS
Table 5.7.3-1:
Comparison of the Annual and Seasonal Mean Number of Seals Observed
along the Lower Churchill River, 1996–2005
1
Year
1996
1999
2000
2005
1.
2.
3.
3
Maximum Number of Seals
Season
2
Count
Range
Mean
SE
Seasons Combined
57
2–18
7.6
0.6
Summer
31
2–8
4.4
0.3
Fall
12
4–12
8.7
0.7
Seasons Combined
80
0–20
10.2
0.7
Spring
34
0–17
7.8
0.9
Summer
36
1–20
14
0.8
Fall
10
0–13
4.6
1.9
Seasons Combined
93
0–29
12.9
0.7
Spring
38
2–29
12.8
1
Summer
32
0–20
11.9
1.3
Fall
23
7–22
14.4
0.9
Seasons Combined
74
0–15
5.2
0.5
Spring
13
0–8
5.1
0.7
Summer
29
0–15
5.2
0.9
Fall
32
1–11
5.3
0.6
Maximum hourly counts from systematic surveys were pooled for each year, and all data were included, regardless of the
number of hourly observations on any given day.
Significant differences in the mean annual number of seals were observed (Kruskal-Wallis H 0.05, 3 = 17.297, p < 0.001);
entire data set used in this comparison.
Non-significant differences between years are observed if 2005 data are excluded (Kruskal-Wallis H 0.05, 2 = 1.814,
p < 0.404).
DECEMBER 2015
5.7-16
WATER – SEALS
b)
a)
Source: Bernhardt (2006).
Dashed red line indicates the 50 m isobath.
Figure 5.7.3-2:
Average Daily Locations for 17 Juvenile and Adult Harbour Seals Satellite
Tagged in the Churchill River Estuary, Western Hudson Bay, during Fall, 2001
and 2002
5.7.3.4
Cumulative Effects of Hydroelectric Development on Seals
in Area 4
5.7.3.4.1
Summary
•
There is insufficient information available to assess the effects of CRD on the abundance and
distribution of harbour seals within the lower Churchill River and estuary. However, local knowledge
suggests that seal numbers may have increased in the lower Churchill River, which may have been
due to decreased flow/water levels and increased availability of haul-out locations.
•
Construction of the Lower Churchill River Water Level Enhancement Weir Project resulted in a minor
shift (less than 1 km) in haul-out locations used by seals. Post-weir seal numbers in the river and
estuary were comparable to those observed in pre-weir years (Bernhardt 2000, 2001, 2003, 2006);
however, current information indicates that these numbers have increased considerably over the last
decade (Florko 2015). These increases suggest that despite the minor displacement of seals to haulout areas downstream, the weir did not negatively impact seal abundance in the Churchill River and
estuary.
•
It is unknown how other changes in the area may have influenced seal abundance, including a
voluntary moratorium on seal harvest at the weir and anthropogenic impact at haul-out areas through
access limitations due to low water.
DECEMBER 2015
5.7-17
WATER – SEALS
5.7.4
Summary of the Effects of Hydroelectric
Development in the Region of Interest on Seals
The effects of hydroelectric development on seals relate primarily to the displacement of haul-out sites
within the Nelson and Churchill River estuaries. Increasing seal numbers in post-hydroelectric
development years and their use of alternate areas for hauling out suggest that despite minor
displacements, seal abundance in the RCEA ROI does not appear to have been materially affected.
DECEMBER 2015
5.7-18
WATER – SEALS
5.7.5
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Publishers B. V., Amsterdam, The Netherlands. 327-340 pp.
Shaughnessy, P.D., Nichols, A.O., and Briggs, S.V. 1999. Interactions between tourists and wildlife at
Montague Island: fur seals, little penguins and crested terns. Report to the South Australian
National Parks and Wildlife Service. CSIRO Wildlife and Ecology, Canberra, Australia.
Smith, T.G. 1975. Ringed seals in James Bay and Hudson Bay: population estimates and catch statistics.
Arctic 28(3): 170-182.
Smith, T.G. 1981. Notes on the bearded seal, Erignathus barbatus, in the Canadian Arctic. Canadian
Technical Report of Fisheries and Aquatic Sciences 1042. 49 pp.
Stewart, D.B. and Howland, K.L. 2009. An ecological and oceanographical assessment of the alternate
ballast water exchange zone in the Hudson Strait region. DFO Canadian Science Advisory
Secretariat Research Document. 2009/008. vi + 96 p.
Stewart, D.B., and Lockhart, W.L. 2005. An overview of the Hudson Bay marine ecosystem. Canadian
Technical Report of Fisheries and Aquatic Sciences 2586: 487 pp.
Suryan, R.M., and Harvey, J.T. 1999. Variability in reactions of Pacific harbour seals, Phoca vitulina
richardsi, to disturbance. Fisheries Bulletin 97: 332-339.
Terhune, J.M. 1985. Scanning behaviour of harbour seals on haulout sites. Journal of Mammalogy 66:
392-395.
The Manitoba Historical Society. 2015a. Manitoba History: Exploring Northern Skies: The Churchill
Research Range. http://www.mhs.mb.ca/docs/mb_history/44/exploringnorthernskies.shtml
(Accessed October 1, 2015).
The Manitoba Historical Society. 2015b. Historic Sites of Manitoba: Churchill Grain Terminal and Port
Facilities (Churchill). http://www.mhs.mb.ca/docs/sites/churchillgrainterminal.shtml (Accessed
October 1, 2015).
Tollit, D.J., Greenstreet, S.P.R., and Thompson, P.M. 1997. Prey selection by harbour seals, Phoca
vitulina, in relation to variations in prey abundance. Canadian Journal of Zoology 75: 1508-1518.
Watts, P. 1992. Thermal constraints on hauling out by harbour seals (Phoca vitulina). Canadian Journal
of Zoology 70: 553-560.
DECEMBER 2015
5.7-25
WATER – BELUGA
5.8
Beluga
5.8.1
Introduction
Beluga whales (Delphinapterus leucas) are circumpolar, ranging from 82°N in the Arctic to 47°N in the St.
Lawrence Estuary. Over 20 stocks or subpopulations have been tentatively identified using a combination
of behavioural, genetic and contaminant data (Martin and Reeves 2000; Reeves et al. 2014). Combined,
these subpopulations comprise a minimum of 150,000 beluga (International Whaling Commission 2000;
Reeves et al. 2014), of which approximately 115,000 inhabit Canadian waters. In summer, most stocks
maintain distinct geographic distributions; however, mixing can occur during spring and fall migrations
and in overwintering habitat. Seven beluga stocks have been identified in Canadian waters: St. Lawrence
Estuary; Ungava Bay; Eastern Hudson Bay; Western Hudson Bay (WHB); Eastern High Arctic-Baffin Bay;
Cumberland Sound; and Eastern Beaufort Sea stocks (Committee on the Status of Endangered Wildlife
in Canada [COSEWIC] 2004) (Map 5.8.1-1).
Belugas inhabiting the Churchill and Nelson River estuaries belong to the WHB stock. This stock is the
largest in the world with an estimated 57,000 whales (95% confidence level [CL] = 37,700–87,100)
(Richard 2005). Large aggregations occur in both estuaries during the summer, with the largest
proportion inhabiting the Nelson River area. Belugas maintain strong fidelity to summering areas, and
although they return to the same sites every year (Caron and Smith 1990; COSEWIC 2004), they are
known to travel large distances between areas (Richard and Orr 2003). It is unclear why belugas
congregate in estuaries and shallow nearshore areas. Reasons for this behaviour may include a
combination of factors such as thermoregulatory advantage (Fraker et al. 1979; Hansen et al. 1988);
moulting and growth (Watts et al. 1991); feeding (Kleinenburg et al. 1964); calving (Sergeant 1973;
Sergeant and Brodie 1975); social functions; and avoidance of predators such as orcas (Orcinus orca)
(Lawrence et al. 1992). Killer whales were not known to inhabit Hudson Bay prior to the mid-1900s
(Degerbol and Freuchen 1935, cited in Ferguson et al. 2010; Reeves and Mitchell 1988) and until
relatively recently, their presence in Western Hudson Bay was considered to be rare. Current evidence
suggests that killer whale occurrence in Hudson Bay is increasing exponentially, likely in response to
decreasing sea ice in Hudson Strait (Ferguson et al. 2010).
Beluga move offshore into deeper waters in mid-August and spend several weeks diving to the seafloor
to (presumably) feed on fish and invertebrates prior to the fall migration (Smith and Martin 1994;
Martin et al. 2001; Richard et al. 2001). Mating occurs in overwintering areas, which are shared by
multiple stocks (COSEWIC 2004). The WHB population is believed to overwinter in Hudson Strait
(Finley et al. 1982; Richard et al. 1990; Richard 1993; Richard and Orr 2003; Richard et al. 2005;
Smith 2007) and as far east as the coast of Labrador (Brice-Bennett 1978 in COSEWIC 2004). Spring
migration to summering areas occurs during late April/May (Sergeant 1973). Although migration routes
have not been fully documented, the majority of WHB belugas are believed to follow the eastern coast of
Hudson Bay south to the Belcher Islands, and then across through the pack ice to arrive along the
Manitoba coast in late May and early June. A much smaller number of animals move westward towards
DECEMBER 2015
5.8-1
WATER – BELUGA
Southampton Island. Spring and fall movements of Hudson Bay beluga are outlined in Stewart and
Lockhart (2005).
Beluga can reach ages of 25–30 years (Brodie 1969). Females reach sexual maturity at a mean age of
five years and typically give birth to a single calf (Sergeant 1973). Gestation time is 14.5 months, and the
calving interval is approximately three years (Sergeant 1973). Richard (1993) proposed an estimated rate
of increase of 2–3% per year for the global beluga population. No other estimates have been published
for beluga.
In Canada, belugas are managed by the Department of Fisheries and Oceans Canada (DFO) under the
Fisheries Act and Marine Mammal Regulations. This species has been commercially and domestically
harvested in Hudson Bay, although commercial harvests ceased in the late 1960s (Reeves and Mitchell
1989). Commercial harvesting of beluga for oil dates back to the 1600s. Commercial harvests were
relatively sporadic through time, but were intensive during some periods (e.g., 4,500 between 1948 and
1958; Reeves and Mitchell 1989). Belugas have been domestically harvested throughout Hudson Bay for
oil, food, skin and dog food (Reeves and Mitchell 1989). Although domestic harvests continue to hold
cultural and social significance in the Canadian Arctic, few, if any, belugas are currently harvested in the
Churchill and Nelson River areas (Manitoba Hydro and the Town of Churchill 1997; Lower Nelson
Overview Study Team 1981). Between 1967 and 1992, 68 belugas were live-captured in the Churchill
River estuary for zoos and aquariums around the world (DFO 2008). Live captures are regulated both
internationally through the Convention on International Trade in Endangered Species of Wild Fauna and
Flora (CITES) and non-convention members, and nationally under the 1993 Marine Mammal Regulations
which are overseen by DFO (Richard 1993). Between 1975 and 1992/93, 53 live-captured belugas were
traded to other countries under CITES permits (Richard 1993). This practice was banned by the
Government of Canada in 1992 (DFO 2008).
Belugas have been red-listed by the International Union for Conservation of Nature (IUCN) as “Near
Threatened”, with some stocks described as in serious trouble and others reduced in size but viable
(Jefferson et al. 2012). The Committee on the Status of Endangered Wildlife in Canada categorizes the
WHB beluga stock as “Special Concern” due to hunting pressure along migration routes, unknown effects
of freshwater flow regulation on estuarine summer habitat resulting from hydroelectric development, and
disturbance from potential increases in shipping (COSEWIC 2004). Natural limiting factors for beluga
include ice entrapment (Mitchell and Reeves 1981; Brodie 1982), and predation by polar bears and orcas
(Smith 1985; Lowry et al. 1987a, b).
DECEMBER 2015
5.8-2

Part 4 - Manitoba Hydro

Transcription

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