2008 Harbour Clam Baseline, Resource and Habitat Survey

Transcription

Clam (Austrovenus stutchburyi) Resource and Habitat
Survey in Otago Harbour (COC3), Otago, 2008
prepared by
Ryder Consulting
June 2008
2
Stock Assessment of Clams (Austrovenus stutchburyi) in
Otago Harbour (COC3), Otago, 2007
prepared by
Brian Stewart
Ryder Consulting
June 2008
Ryder Consulting Ltd.
PO Box 1023
Dunedin
New Zealand
Ph: 03 477 2113
Fax: 03 477 3119
Table of Contents
8.
Executive Summary:................................................................................... 4
9.
Introduction ................................................................................................ 4
10.
Review of the Fishery................................................................................. 5
11.
Research..................................................................................................... 6
12.
Results...................................................................................................... 13
13.
Discussion and Management Implications ................................................ 31
14.
Conclusions.............................................................................................. 32
Acknowledgements ........................................................................................... 32
15.
References................................................................................................ 33
Appendix 1. Clam Raw Data ............................................................................. 35
Appendix 2. Survey Sites................................................................................... 39
Appendix 3. Quadrat Photographs ..................................................................... 47
Appendix 4. Invertebrate Raw Data ................................................................... 50
Appendix 5. Cores ............................................................................................. 54
1.
Date:
30 April 2008
2.
Contractor:
Ryder Consulting Ltd
PO Box 1023
Dunedin
NEW ZEALAND
3.
Project Title:
Clam resource and habitat survey in Otago Harbour (COC3),
Otago, 2008
4.
Project Code:
N/A
5.
Project Leader:
Brian Stewart
6.
Start date:
10 March 2008
7.
Expected completion date:
8.
Executive Summary:-
30 April 2008
This is a draft report describing the results of a survey of clam (cockle) biomass and
community structure on beds in Otago Harbour, 2008.
Stratified random sampling was carried out to estimate abundance and biomass of clams on
two areas (sanitation areas 1804 and 1805) in Otago Harbour. From 158 stations
(quadrats) at Area 1804 and 150 stations at Area 1805 the total clam biomass for each Area
was estimated to be 6153.21 tonnes for 1804 and 7288.51 tonnes for 1805, with 95%
confidence intervals of ±451.75 tonnes and ±790.00 tonnes respectively. Biomass was
also calculated for several size classes (2-<19mm, ≥19 - <30mm and ≥30mm, ≥28mm) of
clams. Estimates of yield (MCY and CAY) were calculated by modelling F0.1 for clams in
the inlet based on local growth data and on current length to weight relationships. An
estimate of yield based on YPR for M = 0.3 (Area 1804) and 0.2 (Area 1805) and recruited
size = 30mm was calculated at 441.60 tonnes for Area 1804 and 255.55 tonnes for Area
1805. Communities associated with each of the areas are similar to those in comparable
habitats throughout New Zealand. Substrate on both areas comprises mainly fine sand.
Future surveys will indicate whether or not proposed harvesting of clams on these areas
will change biomass and/or the communities associated with them. It is recommended that
future surveys use a similar experimental design to that used in the current survey.
9.
Introduction
9.1
Overview
This report presents the results of the size structure and biomass survey for clams along
with the community and substrate survey carried out in Otago Harbour in March and April
2008. MCY and CAY are calculated based on the results of the biomass surveys and
biomass, community structure and substrate characteristics are also given. Abundance,
and size structure of clams are presented.
9.2
Description of Fishery
The cockle, or littleneck clam, Austrovenus stutchburyi, formerly known as Chione
stutchburyi, is a shallow burrowing suspension feeder of the family Veneridae. It is found
5
on sheltered beaches of soft mud to fine sand throughout New Zealand and on the Chatham
Islands (Morton and Miller 1973).
Commercial harvesting of clams, by hand picking, has been carried out at Papanui and
Waitati Inlets since 1983 (Annala et al. 2003) and continues year round. Commercial
fishers target clams in the 28-34mm size range. Clams, as with most intertidal shellfish,
are considered an important food source by both Maori and non-Maori. Such traditional
and recreational harvesters take a small harvest from Waitati Inlet targeting mainly larger
animals (>30mm).
10.
Review of the Fishery
10.1
TACCs, Catch, and Landings
Otago Harbour contains what is probably the biggest and most productive resource of
clams (Austrovenus stutchburyi) in New Zealand (Breen et al. 1999). At around 80,000t
total biomass estimate, it represents a significant shellfish resource. Since 1988 Southern
Clams Ltd has maintained that the commercial harvest of clams, specifically from the
middle banks of the Harbour, is a natural and sustainable use of the resource. Furthermore,
an industry based on this could provide benefits, both social and economic, and ensure its
sustainable management.
Otago Harbour was closed for commercial harvesting of shellfish, under a regulation
passed in the 1960’s. The reason given at the time was concern over the sanitary status of
the shellfish growing waters. Since that time all sewerage outfalls into the harbour have
been closed and polluting industrial sources no longer discharge into the Harbour waters.
Otago Harbour currently remains closed, but the reason for its closure is, according to
Southern Clams Ltd, no longer valid. Following more than a year’s shellfish sanitation
research by Southern Clams Ltd, it appears that the growing waters, and shellfish on the
middle banks of the harbour, are of better bacteriological quality than either of the two
areas currently certified (Waitati and Papanui Inlets). Due to one of these historical
harvest areas (Papanui Inlet) being currently closed because of high bacteriological levels,
all harvesting is currently from Waitati Inlet, thus leaving the company with an insecure
supply base, and no alternative areas for harvest in the event of closure.
Southern Clams Ltd’s declared intention to harvest in the Harbour dates back to 1988, and
has recently been met with strong concern from some parties. Critical opposition to
harvesting clams (cockles) in Otago Harbour has focussed on the impact of harvesting.
Critics state that while the techniques and management regimes proposed are the same as
the company’s practices in two well developed commercial harvest areas nearby, the
Harbour proposal is neither on the same scale, nor is it in the same habitat. It is argued
therefore that the extensive studies on the impact of harvesting undertaken on these other
areas will not necessarily be applicable in the Harbour.
It is to address these concerns that Southern Clams Ltd has commissioned this study.
10.2
Recreational and Maori Customary Fisheries
Clams are taken by recreational fishers in many areas of New Zealand. The recreational
fishery is harvested entirely by hand digging. Relatively large clams are preferred and
clams generally ≥30mm are taken.
6
Amateur harvest levels in FMA 3 were estimated by telephone and diary surveys in
1993–94 (Teirney et al. 1997), 1996 (Bradford 1998) and 2000 (Boyd & Reilly 2004)
(Table 1). COC3A (which includes Otago Harbour) is a smaller area within FMA 3.
Harvest weights are estimated using an assumed mean weight of 25g (for clams >30mm).
The estimates for 1993-94 and 1996 are considerably less than the 2000 estimate and are
considered to substantially underestimate the recreational harvest. The 2000 estimate is
considered to be a more reliable estimate of absolute harvest.
Table 1: Estimated numbers of clams harvested by recreational fishers in FMA 3, and the corresponding
harvest tonnage. Figures were extracted from a telephone and diary survey in 1993–94, and the
national recreational diary surveys in 1996 and 2000.
Fishstock
1993–94 FMA 3
1996 FMA 3
2000 FMA 3
Survey
South
Harvest (N)
106,000
144,000
1,476,000
% c.v.
51
–
45
Harvest (t)
2.7
3.6
36.9
Many intertidal bivalves, including clams, are very important to Maori as traditional food,
particularly to Huirapa and Otakou Maori in the Otago area. Tangata tiaki, who issue
customary harvest permits for clams in Otago, report the following number of clams have
been taken, but not necessarily from the Otago Harbour:
1998: 750 individuals
1999: 0 individuals
2002: 0 individuals
The Ministry of Fisheries reports that for the years since 2004 there have been no reported
customary take under the regulations for COC3 (which includes Otago Harbour) apart
from 1280 individuals for the period July – September 2007. The Ministry further states
that local customary fishers generally utilise the daily amateur bag for their customary
needs.
10.3
Other Sources of Fish Mortality
No quantitative information is available on the magnitude of illegal catch but it is thought
to be insignificant (Roger Belton, pers. comm.).
No quantitative information is available on the magnitude of other sources of mortality
within the harbour.
11.
Research
11.1
Objectives
1.
Measure and document the initial biomass of the virtually virgin shellfish stocks.
Monitor and record on a bi-annual basis any changes in biomass, growth and
recruitment of the target clam species (Austrovenus stutchburyi) following harvest.
Target cv 10%.
2.
Derive sustainable COC yield estimates, on both CAY and MCY basis.
7
11.2
3.
To systematically characterise the species and ecology of the Harbour shellfish beds in
the study area before harvesting commences and then again after harvesting. Surveys to
be repeated after 3 years and after 5 years.
4.
Characterise the physical environment prior to harvesting and measure changes in the
physical environment of the areas subject to harvesting and control areas. Key factors
such as substrate composition, and sediment stability to be documented. Surveys to be
conducted before harvesting commences and after harvesting. Surveys to be repeated
after 3 years and after 5 years.
Methods:
11.2.1 Specific Objective 1: Biomass
Based on the previous surveys by Wildish (1984a,b), Stewart et al. (1992), Breen et al.
(1999), Wing et al. (2002) and Stewart (2006) a two phase stratified random sampling
regime was undertaken. Strata were assigned to Areas 1804 and 1805 (Figure 1) according
to the density of clams found in preliminary surveys carried out by Southern Clams Ltd. It
should be pointed out that the surveyed areas do not comprise the entire sanitation area in
either case. For Arera 1804 the survey area comprised 82% of the sanitation area. For
Area 1805, the surveyed area comprised 51% of the sanitation area (Figure 1). In
“extensive” areas (i.e. areas with a low known density of clams) strata were 200m x 200m
(Figures 2 and 3). Sukhatme (1954) suggests that sampling effort should be higher where
species are more densely aggregated. Consequently, in “intensive” areas (i.e. areas with a
high known density of clams) strata were 100m x 100m (Figures 2 and 3), as in previous
surveys (e.g. Wildish 1984a,b; Stewart et al. 1992; Breen et al. 1999; Wing et al. 2002;
and Stewart 2006, 2008).
A minimum of three stations was assigned to each stratum, in both intensive and extensive
areas (Figures 1 and 2). Breen et al. (1999) showed that the 20% target coefficient of
variation (c.v.) could be met by sampling approximately 80 stations at each site, and opted
for a target of 100 stations per site. However, additional work was required to meet the
target c.v. (Breen et al. 1999). Stewart et al. (1992), Wing et al. (2002) and Stewart (2006,
2008) used considerably more stations and achieved very low c.v’s. Southern Clams Ltd
required a lower target c.v. than 20% and stipulated 10%. For this survey then, the aim
was to achieve similar c.v.’s to Stewart et al. (1992), Wing et al. (2002) and Stewart (2006,
2008). Thus, an initial target of approximately 130-140 stations was allocated within
phase 1 for each area. At the completion of phase 1 sampling, mean and variance were
calculated for stations within each stratum and Phase 2 stations were added iteratively to
strata using the “area mean squared” method described in Francis (1984) and Manly et al.
(2002). Ultimately, 158 stations were allocated over 48 strata in Area 1804 and 150
stations allocated over 43 strata in Area 1805 (Figures 2 and 3). The position of each
station within each stratum was assigned randomly using grid co-ordinates generated by a
random number program in conjunction with the GPS program Fugawi™ and was located
using hand-held GPS.
Biomass was then estimated for each “Area”. The areas used are, in actuality, sub areas
within shellfish sanitation areas 1804 and 1805. Boundaries of areas may vary slightly
from year to year according to clam density encountered by harvesters. Surveyed areas for
2008 are outlined in red and labelled in yellow in Figures 1, 2 and 3.
At each station a 316mm x 316mm (0.1m2) quadrat was excavated to a depth of 100mm
using a venturi suction device, as employed by Wing et al. (2002) and Stewart (2006,
8
2008), to ensure all live clams were retrieved. Samples were sieved on site using a 2mm
mesh size and all live clams were removed from the sample, bagged in labelled polythene
bags, and stored in chilly-bins for later analysis.
In the laboratory all samples from individual quadrats were weighed to the nearest 0.1g.
Subsamples of clams, 443 from 1804 and 525 from 1805, were individually measured
along the longest shell dimension (shell length) to the nearest 0.1mm using vernier
callipers and weighed to the nearest 0.1g.
Thus the biomass for any size group within any area could be estimated from the mean
biomass density for a particular size group in that area and the areal size of that area. The
same applies to any size group within any stratum. Biomasses were calculated for what
were formerly termed commercial sized clams (≥30mm) and non-commercial clams
(<30mm) in each area and for clams ≥28mm and <28mm. In addition, biomasses were
calculated for each area for the following sizes classes: >2 - <19mm and ≥19 - <30mm,
which have also been used in previous surveys. Total biomass for the area was calculated
by summing biomasses for all strata within each area. Clams <19mm generally have
poorly developed gonads and are, therefore, considered juveniles (Larcombe 1971).
Subsample data were log transformed to fit the assumption of normal distribution and a
regression line fitted using least squares in Microsoft Excel®. Weight per unit length for
any clams in the Harbour could then be calculated using the equation for the relevant
length/weight regression line. Residuals for the log transformed data and line fit for each
inlet were also plotted in Excel®. Size/frequency histograms were produced for size
classes of clams within each inlet. After measurement all shellfish were returned to Otago
Harbour.
For the calculation of 95% confidence intervals, estimates of the sample variance in each
stratum were made based on the total biomass values for each quadrat, as in Stewart et al.
(1992) using:
Si2 = Σ(xij-xi)2/(ni-1)
Where S2i equals the sample variance for stratum i; xij-xi equals the difference between each
quadrats total biomass (xij) and the mean quadrat biomass value (xi); and n i equals the
number of quadrats taken in stratum i. These sample variances were then used to produce
95% confidence intervals for each inlet biomass estimate using:
+1.96√ΣNi2Si2/ni
Where Ni equals the number of possible quadrats that could be placed in stratum i.
9
Figure 1.
Mid portion of Otago Harbour showing the location of sanitation areas 1804 and 1805 with strata superimposed.
10
Figure 2.
Area 1804, Otago Harbour, showing location of sampling stations, 200m grid squares and 100m grid squares.
11
Figure 3.
Area 1805, Otago Harbour, showing location of sampling stations, 200m grid squares and 100m grid squares.
12
11.2.2 Specific Objective 2: Yield
Previous surveys (Breen et al. 1999, Wing et al. 2002, Stewart 2006) calculated yield per
recruit using von Bertalanffy growth parameters and the Ricker equation. A similar
approach was taken for this survey. Following Annala and Sullivan (1996) biomass yield
estimates (yield per recruit) for clams in Waitati Inlet were calculated using their Method 1
for maximum constant yield (MCY) and their Method 1 for current annual yield (CAY).
MCY = 0.25 F0.1 B0
i.e.
where F0.1 is the fishing mortality at the point on a YPR curve where the slope is 0.1 of that
at Fo, and B0 is the recruited biomass, and
CAY = (F0.1/ Z) (1-exp(-Z) Bbeg
where Z is the total mortality.
These calculations require an estimate of F0.1 (Hilborn and Walters 1992) that requires the
plotting of a von Bertalanffy growth curve using
Lt = L∞(1−exp-(K(t-t0))
to estimate asymptotic size (L∞) and the rate at which asymptotic size is approached (K).
Yield able to be taken from the surveyed area was calculated from the biomass estimates
for clams ≥28mm as determined in Objective 1 from this survey, coupled with estimates of
von Bertalanffy growth curve parameters calculated from growth data collected over 20042006 (Stewart 2006). In previous surveys Breen et al. (1999), Wing et al (2002), and
Stewart (2006) used parameters for Papanui Inlet: i.e. L∞ = 40.296mm, K = 0.311, t0 =
0.0mm, size at recruitment = 30mm to calculate MCY. F0.1 was calculated as being the
fishing mortality rate at which the slope of the yield per recruit curve, as a function of
fishing mortality, is 10% of its value near the origin as in Breen et al. (1999), Wing et al.
(2002), and Stewart (2006). For the current survey, F0.1 was estimated for M = 0.2, 0.3 and
0.4/yr, where M = the instantaneous mortality.
11.2.3 Specific Objective 3: Assess Biota
To assess the flora and fauna associated with the clam population within the areas to be
investigated, four 10m x 10m quadrats were sampled within a control area at each site and
four in an impact area at each site. Quadrats were photographed and percentage cover of
macroalgae estimated. Ten randomly placed 200mm deep core samples were collected
from each quadrat using a 125mm diameter coring device. Cores were photographed to
allow determination of the depth of the redox discontinuity layer if present. Cores were
then sieved using a 500µm sieve and all animals retained preserved and returned to the
laboratory. Animals were identified to a minimum of family level in the laboratory and
enumerated.
Simple measures of species diversity (number of different ‘types’ of animals per sample)
and animal abundance (number of animals per sample) were calculated from the collected
data. A diversity index was also calculated using the Shannon-Weiner method (Zar 1996).
Such indices provide a ready method for comparing diversity at sites from year to year or,
in this case, before and after harvesting and for comparing impact sites with control sites.
13
For other community analyses the data was transformed (log(x+1)) to meet the statistical
requirements of the tests used.
In addition, variability among sites was measured using the Index of Multivariate
Dispersion (IMD) (Warwick 1993), with IMD values calculated for the invertebrate
samples at each location and compared visually. Ordination was used to ‘graph’ the
invertebrate communities. In such plots, how close the core values appear to each other
reflects how similar they are in terms of species composition and abundance patterns.
The survey will be repeated immediately after harvesting has taken place. Analysis of
similarities will be used to test whether there were significant differences between the
invertebrate communities at different locations and among treatments. Finally, analysis of
similarities will be used once more to test whether there is a significant difference between
communities before and after impact and among impact and control sites. Irwin’s (1999)
research on the impact of harvesting in Waitati Inlet demonstrates that most effects are
barely detectable after 30 days.
This longitudinal study, with re-surveys over a five year period in a similar ecosystem,
should provide an even better understanding of long-term harvest impacts. The species that
are responsible for differences between the groupings will be identified using similarity
percentages (Warwick and Clarke 1993).
11.2.4 Specific Objective 4: Characterise substrate
As an adjunct to the faunal sampling an investigation of the effects of harvesting on
substrate was also undertaken. This involved a BACI (Before, After, Control, Impact)
design (Kingsford and Battershill, 1998) in which three random cores 80mm diameter and
200mm deep were collected from each of four representative 1m2 quadrats within a control
area and four representative 1m2 quadrats within an area designated for harvesting, giving
a total of 24 cores per sanitation area. The survey will be repeated immediately after
harvesting has taken place. These same sites will be re-sampled at 3 years and 5 years.
Individual core samples from each quadrat were subsampled at 50mm 100mm and 200mm
depths with each subsample being processed at Ryder Consulting’s laboratory for grain
size analysis and analysis of simple organic content by loss on ignition (e.g. Irwin 1999).
12.
Results
12.1
Objective 1: Biomass
Between 12 March and 18 March 2008 a total of 144 phase 1 stations were sampled at
sanitation area 1804, Otago Harbour, with an additional 14 phase 2 stations being added as
appropriate (see Figure 2 for station locations). During the same time period a total of 129
phase 1 stations were sampled at sanitation area 1805, Otago Harbour, with an additional
21 phase 2 stations being added as appropriate (see Figure 3 for station locations).
Quadrats for all stations were sifted through a 2mm sieve on site and live clams collected,
sealed in individually labelled bags, and then returned to the laboratory for weighing.
Absolute ‘recruited’ biomass (clams ≥30mm ) for each Area, i.e. the biomass that is
vulnerable to fishing by both recreational and commercial fishers, was calculated from the
raw data (Appendix 1) and is presented below (Table 2). Associated 95% confidence
limits are also shown.
14
Table 2.
Biomass (t) for clams of size ≥30mm in individual areas (± 95% confidence limits). CV
=coefficient of variation. Areas shown in Figures 2 and 3.
Area
1804
1805
Otago Harbour (t)
5472.61±401.78
3526.08±382.21
CV (%)
3.67
5.42
The total biomass for each size class of clams, as used in previous surveys, was then
calculated for each area (Tables 3a and 3b). Associated 95% confidence limits and
coefficients of variation (c.v.) are also shown. The target c.v. of 10% was met in each case
for both areas.
Table 3a.
Estimated biomass calculated for particular size classes of clams in the surveyed area of
Area 1804. CI = 95% confidence interval, CV = coefficient of variation.
Size Class
>2 - <19mm
≥19 - <30mm
≥30mm
Total (t)
<28mm
≥28mm
Table 3b.
Biomass (t)
208.35
472.26
5472.61
6153.21
472.26
5680.96
CI (t)
15.30
34.76
401.78
451.75
34.46
414.55
Variance (t2)
7.58513E+13
2.99488E+14
4.02339E+16
5.0403E+16
2.99488E+14
4.33891E+16
CV(%)
4.18
3.66
4.39
3.65
3.66
3.67
% of total Area biomass
3.4
7.6
88.9
100
7.6
92.3
Estimated biomass calculated for particular size classes of clams in the surveyed area of
Area 1805. CI = 95% confidence interval, CV = coefficient of variation.
Size Class
>2 - <19mm
≥19 - <30mm
≥30mm
Total (t)
<28mm
≥28mm
Biomass (t)
CI (t)
Variance (t2)
CV(%)
374.82
3387.25
3526.08
7288.15
3054.08
4234.07
40.63
367.16
382.21
790.00
331.05
458.95
4.12215E+14
3.37077E+16
3.65199E+16
1.56026E+17
2.73921E+16
1.39148E+14
5.416
5.420
5.419
5.420
5.419
0.28
% of total
Area biomass
5.1
46.5
48.4
100
41.9
58.1
Length versus weight curves were constructed from subsample data for each area. Data
were log transformed to better fit the assumption of normal distribution of variance
(Figures 4a and 4b) and regression lines fitted using least squares.
15
Area 1804 (n = 443)
2.5
y = 3.2089x - 3.7168
R2 = 0.9732
2
1.5
Log Weight
1
0.5
0
-0.5
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
-1
-1.5
-2
Log Length
Figure 4a. Relationship between log shell length and log weight, Area 1804, Otago Harbour, with
regression line fitted (pink line).
Area 1805 (n = 525)
2
y = 3.2426x - 3.778
R2 = 0.978
1.5
Log Weight
1
0.5
0
0
0.5
1
1.5
2
-0.5
-1
-1.5
Log Length
Figure 4b. Relationship between log shell length and log weight, Area 1805, Otago Harbour, with
regression line fitted (pink line).
The log length to log weight relationship showed good agreement for each area with the
regression lines for 1804 having an R2 value of 0.9732 and for 1805 R2 = 0.978. Residuals
calculated for the log transformed data for each area show a good degree of homoscedacity
(Figures 5a and 5b).
16
Area 1804 (n = 443)
1.5
1
Residuals
0.5
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
-0.5
-1
-1.5
Log Length
Figure 5a.
Plot of residuals calculated for log length, Area 1804.
Area 1805 (n = 525)
1.5
1
Residuals
0.5
0
0
0.5
1
1.5
2
-0.5
-1
-1.5
Log Length
Figure 5b.
Plot of residuals calculated for log length, Area 1805.
Although the regression lines for each area give a good fit, a previous discussion with Dr
David Fletcher, a statistician with the Department of Mathematics and Statistics at the
University of Otago (Stewart 2006), suggested that there was no advantage to be gained by
using the estimated weights of clams rather than the sampled (actual) weights in the
calculation of biomass for this survey. The equations do, however, allow the approximate
mass for a clam belonging to any given size class to be estimated.
17
A plot of size frequency distribution shows very clearly that clams on Area 1804 are
generally larger than those on Area 1805 (Figure 6). This may be due to Area 1804 being
closer to the entrance of the Harbour and, as a consequence more readily supplied with
food. This will need to be investigated further to be verified.
Size frequency for different Areas
1805
1804
20.00
18.00
16.00
Percentage
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
0
2
4
6
8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60
Length (mm)
Figure 6.
12.2
Size frequency histograms for clams on Areas 1804 and 1805.
Objective 2: Yield
Clam growth data specifically for Otago Harbour is not available so growth data for
Waitati Inlet a short distance to the north is used in this study. Following Annala and
Sullivan (1996), biomass yield estimates (yield per recruit) for clams in Otago Harbour
was calculated using their Method 1 for maximum constant yield (MCY) and their Method
1 for current annual yield (CAY).
i.e.
MCY = 0.25 F0.1 B0
where F0.1 is the fishing mortality at the point on a YPR curve where the slope is 0.1 of that
at F0, and B0 is the virgin recruited biomass, and
CAY = (F0.1/ Z) (1-exp(-Z) B0
where Z is the total mortality.
These calculations require an estimate of F0.1 (Hilborn and Walters 1992) obtained from
yield per recruit modelling using the von Bertalanffy equation
Lt = L∞(1−exp-(K(t-t0))
to estimate asymptotic size (L∞) and the rate at which asymptotic size is approached (K).
The von Bertalanffy growth parameters used here are based on the age at size data
collected by Stewart (2006) for Waitati Inlet (Figures 7 and 8). It is expected that clam
growth in Otago Harbour is not dissimilar to growth in adjacent inlets. However, it is
18
recommended that growth data using tag and recapture experiments be collected for the
Otago Harbour to verify this.
45
40
Length at t+1 (mm)
35
30
25
20
15
10
5
0
0
5
10
15
20
25
30
35
40
45
Length at t (mm)
Figure 7.
Ford-Walford plot for clams at Waitati Inlet (from Stewart 2008).
45
40
35
Length (mm)
30
25
20
15
10
5
0
0
5
10
15
20
25
Age (years)
Figure 8.
von Bertalanffy growth curve for clams at Waitati Inlet (from Stewart 2008).
From these data and the above graphs, values for L∞ and K were determined to be
40.95mm and 0.326 respectively. These values are adopted for the present calculation of
MCY and CAY (see Tables 5a-d) and are not dissimilar to those used by Wing et al.
(2002) and Stewart (2006) where the L∞ and K used were 40.295mm and 0.311
respectively. Size at recruitment for this survey is taken to be the size at which clams are
recruited to the fishery; i.e. 30 mm.
Cryer (1997) and Martin (1984) estimated natural rates of mortality for clams to range
between 0.19 to 0.46. For Otago Harbour F0.1 was estimated for M = 0.2, 0.3 and 0.4/yr for
size at first capture of 30mm (Figure 9). For each curve F0.1 was calculated as the point on
the curve where the slope of the curve is 10% of the slope of the curve near the origin
19
(Figure 9). For the current survey F0.1 calculated for Waitati Inlet was used. i.e. 0.2899 for
M = 0.2, 0.3863 for M = 0.3 and 0.5537 for M = 0.4.
Breen et al. (1999), Wing et al. (2002) and Stewart (2006, 2008) used the current recruited
biomass as an estimate of B0 and Bbeg in their calculation of MCY and CAY. However, as
Otago Harbour has never been commercially fished virgin recruited biomass was used in
the current calculation of MCY and CAY. MCY and CAY are presented in Tables 5a, 5b,
5c and 5d.
YPR Waitati Inlet Size at first capture = 30mm
4.5
F0.1
4
3.5
YPR
3
2.5
2
1.5
1
0.5
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
F
Figure 9.
YPR relationships for Waitati Inlet based on growth parameters from Stewart (2006) and
length/weight relationship in Figure 3. Size at first capture = 30mm. Red: M = 0.2, Blue: M =
0.3, Green; M = 0.4
Table 5.
Maximum Constant Yield (MCY) and Constant Annual Yield (CAY) for clams ≥28mm calculated
for Areas 1804 (a) and 1805 (b); and for clams ≥30mm for Areas 1804 (c) and 1805 (d). All
figures are in tonnes.
a.
1804
Recruited biomass
M
0.2
0.3
0.4
>28mm
1805
Recruited biomass
M
0.2
0.3
0.4
>28mm
F0.1
0.2899
0.3863
0.5537
total
lower upper
5680.96 5266.41 6095.51
MCY
lower
upper
CAY
411.73 381.68 441.77 1302.04
548.64 508.60 588.67 1587.85
786.39 729.00 843.77 2027.40
lower
1207.03
1471.98
1879.45
upper
1397.05
1703.71
2175.34
total
lower upper
4234.07 3775.12 4693.02
MCY
lower
upper
CAY
lower
306.86 273.60 340.13
970.42 865.23
408.91 364.58 453.23 1183.44 1055.16
586.10 522.57 649.63 1511.04 1347.25
upper
1075.61
1311.71
1674.82
b.
F0.1
0.2899
0.3863
0.5537
20
Table 5.
Continued….
c.
1804
Recruited biomass
M
0.2
0.3
0.4
>3 0 m m
1805
Recruited biomass
M
0.2
0.3
0.4
>3 0 m m
F0.1
0.2899
0.3863
0.5537
total
lower upper
4572.61 4170.83 4974.39
MCY
lower
upper
CAY
lower
331.40 302.28 360.52 1048.01 955.93
441.60 402.80 480.40 1278.06 1165.76
632.96 577.35 688.58 1631.85 1488.47
upper
1140.10
1390.36
1775.24
d.
F0.1
0.2899
0.3863
0.5537
total
lower upper
3526.08 3143.87 3908.29
MCY
lower
upper
CAY
lower
upper
255.55 227.85 283.25
808.15 720.55 895.75
340.53 303.62 377.44
985.55 878.72 1092.38
488.10 435.19 541.01 1258.37 1121.97 1394.77
It should be noted that 88.9% of the biomass in Area 1804 is harvestable (i.e. >30mm). As
a consequence it may be more appropriate to use M = 0.3 for this area, but 0.2 for 1805.
12.3
Objective 3: Characterisation of the communities associated with the shellfish areas
Areas 1804 and 1805 were visited at low tide on 8 April and 7 April respectively. Eight
sites were visited at each area (Figures 10 and 11). At each site a 10m2 quadrat was
marked out using fibreglass rods and photographed (Appendix 2). Within each quadrat 10
core samples were collected using a 125mm diameter coring device pushed to a depth of
200mm. Cores were sieved on site using a 500µm Endicott sieve and animals retained
were placed in labelled polythene bags for later identification, enumeration and weighing
in the laboratory. Animals were generally identified only to family level as this is
considered enough to allow reasonable characterisation of an invertebrate community
(Bates et al. 2007).
There was a general paucity of macroflora within the majority of surveyed quadrats at each
area (Table 6) (Appendix 3). Quite extensive patches of Zostera novazealandica and Ulva
lactuca were, however, observed on other parts of the areas.
Infaunal communities, however, were reasonably diverse and showed a high abundance of
some animals, with up to 465 oweniid polychaetes per square metre at one site on Area
1804 (Table 7) and in excess of 260 amphipods per square metre at a site on Area 1805
(Table 8). A full set of data can be found in Appendix 4. The communities at both areas
were numerically dominated by polychaete worms and amphipods, as is usual for sheltered
soft shores around New Zealand (Morton and Miller 1973) but the biomass, apart from
clams, was dominated by the wedge shell, Macomona liliana (Tables 7 and 8). Other
animals that contributed a significant amount to overall biomass were crabs, gastropod
snails and some of the larger polychaetes. Biomass is not given for all species as the
balance used read only to 0.1g and consequently, those animals that totalled less than 0.1g
in any quadrat were not recorded.
It should be noted that some species, such as mantis shrimps (Squilla armata) and oysters
(Tiostrea chilensis), were observed at sites on both areas but were absent from any cores.
21
P1
P6
P7
P8
P3
P2
P1
Figure 10. Area 1804 showing location of sampling sites.
P5
P4
22
K5
K6
K7
K8
K1
K2
K3
K4
Figure 11. Area 1805 showing location of sampling sites.
23
Table 6.
Percentage cover of macroalgal species at Areas 1804 and 1805, Otago Harbour (for
photographs of 1m2 quadrats see appendix 3).
1805
1804
Area
Table 7.
Site
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Zostera
novazealandica
80
40
-
Ulva
lactuca
1
5
3
30
10
1
25
8
7
2
-
Ceramium
uncinatum
0.5
1
2
3
5
5
4
4
1
2
-
Gracilaria
chilensis
0.5
0.5
1
2
2
1
1
1
1
-
Enteromorpha
intestinalis
0.5
Number of infaunal animals per square metre at each site in Area 1804 and overall biomass of
significant animals.
Otago Harbour, Area 1804
8-Apr-08
Phylum
Polychaeta
Crustacea
Family
Arenicolidae
Capitellidae
Glyceridae
Lumbrineridae
Nephtyidae
Nereidae
Opheliidae
Oweniidae
Pectinariidae
Spionidae
Syllidae
Terebellidae
Malacostraca
Amphipoda
Mollusca
Location Site 1 Site 2 Site 3 Site 4 Site 5 Site 6 Site 7 Site 8 Tonnes
Sample N o/m2 N o/m2 N o/m2 N o/m2 N o/m2 N o/m2 N o/m2 N o/m2 per bed
Isopoda
Cumacea
Ostracoda
Gastropoda
Bivalvia
Genus/species
33
8
8
106
65
82
130
106
16
0.19
57
33
49
24
33
465
24
33
41
16
Macrophthalmus hirtipes
Halicarcinus spp
Gamaridae
Haustoriidae
Lysianassidae
Oedicerotidae
Phoxocephalidae
8
16
33
82
41
57
8
24
73
8
Trochidae
Veneridae
Mactridae
Tellinidae
Solemyidae
Notoacmea spp
Zeacumantus subcarinatus
Cominella glandiformis
Diloma subrostrata
Micrelenchus tenebrosus
Melagraphia aethiops
Austrovenus stutchburyi
Tawera spissa
Puyseguria spp
Macomona liliana
Solemya parkinsoni
49
8
8
Isocladus armatus
Acmaeidae
Batilliidae
Cominellidae
Trochidae
16
212
8
49
57
8
130
16
24
16
8
90
65
16
33
16
8
24
8
24
16
65
24
65
8
41
41
8
33
24
16
106
16
196
8
8
41
8
106
49
3.02
49
16
8
171
24
33
8
16
16
8.11
6.70
2.36
6.70
73
8
8
24
8
8
8
73
139
73
49
16
8
253
33
33
82
163
41
24
8
33
8
0.09
3.77
5.56
0.09
24
41
8
24
24
24
24
41
24
90
8
33
49
8
0.85
3.40
7.64
5.09
18.20
8
8
41
183.90
0.19
24
Table 8.
7-Apr-08
Phylum
Polychaeta
Location Site 1 Site 2 Site 3 Site 4 Site 5 Site 6 Site 7 Site 8 Tonnes
Sample N o/m2 N o/m2 N o/m2 N o/m2 N o/m2 N o/m2 N o/m2 N o/m2 per bed
Family
Arenicolidae
Glyceridae
Lumbrineridae
Nephtyidae
Nereidae
Nereididae
Opheliidae
Oweniidae
Pectinariidae
Sabellidae
Spionidae
Terebellidae
Hemichordata Enteropneusta
Crustacea
Malacostraca
Amphipoda
Mollusca
Isopoda
Tanaidacea
Cumacea
Ostracoda
Gastropoda
Bivalvia
Genus/species
65
8
90
33
57
16
33
8
8
49
163
8
253
16
49
73
57
8
114
3.67
98
33
82
8
16
16
57
106
8
33
16
65
8
16
49
10.39
11.21
57
122
8
24
82
16
8
179
8
16
9.98
7.84
1.02
4.58
0.41
0.10
24
8
Hemigrapsus crenulata
Halicarcinus spp
Periclimenes batei
Callianassa filholi
Palaemonidae
Callianassidae
Gamaridae
Haustoriidae
Phoxocephalidae
Talorchestia spp
Talitridae
Isocladus armatus
8
16
1
8
16
8
8
24
41
16
49
16
16
8
8
57
8
122
41
16
8
16
8
187
261
73
13.86
1.73
1.73
1.22
1.94
16
24
8
33
24
33
8
8
8
Acmaeidae
Veneridae
Mactridae
Tellinidae
Solemyidae
Notoacmea spp
Puyseguria spp
24
16
24
24
57
106
16
33
41
Macomona liliana
Solemya parkinsoni
57
57
16
8
16
49
16
41
49
8
57
33
8
16
147
41
0.71
6.32
8
16
8
0.92
201.71
0.51
Multi-dimensional scaling was used to plot ordinations showing similarities in the infaunal
communities among sites at each area and between areas. In an ordination plot the closer
symbols are to each other, the more similar they are. Each symbol represents a quadrat
sampled during the survey. The high degree of intermingling of the symbols in the
ordination plot in Figure 12 show that there was little difference in the infaunal community
structure between areas. Within areas, however, there were some sites that were quite
dissimilar with Sites 3 and 6 in Area 1804 forming reasonably distinct groups that show
little overlap with, for example, Site 2 (Figure 13).
25
Figure 12. Ordination showing relationship between the infaunal communities of Area 1804 (green
symbols) and 1805 (blue symbols).
Key: Site 1
Site 2
Site 3
Site 4
Site 5
Site 6
Site 7
Site 8
Figure 13. Ordination showing relationship between the infaunal communities at different sites within Area
1804.
In Area 1805, species within sites are a little more homogeneous. There are still some
loose groupings (e.g. Site 6 and Site 2), but the symbols generally show more overlap than
sites at Area 1804 (Figure 14).
26
Key: Site 1
Site 2
Site 3
Site 4
Site 5
Site 6
Site 7
Site 8
Figure 14. Ordination showing relationship between the infaunal communities at different sites within Area
1805.
Although these ordinations show the relationships among sites and between areas at the
time of the current survey, their real importance will become clearer when repeat surveys
are conducted and ordinations from different surveys compared and comparisons made
between control and impact sites.
Variability in the infaunal community at each site was measured using an index of
multivariate dispersion (IMD) (Warwick and Clarke 1993). Higher values of the IMD
indicate higher variability within a site. Site 7 at Area 1804 is the most variable of all sites
surveyed (Table 9). Site 6 shows the least variability at both Areas 1804 and 1805.
Table 9.
Site
1
2
3
4
5
6
7
8
Overall
IMD Area 1804
0.952
0.846
0.71
1.376
0.792
0.621
1.427
1.276
0.969
IMD Area 1805
1.143
0.702
1.188
1.249
1.259
0.468
1.302
0.69
1.031
Perhaps more useful is a calculation of an infaunal diversity index at each site (Table 10).
The diversity index considers the number of taxa present and the abundance of animals
within each species and provides a score (H’). The higher the value of H’ the more
diverse. The diversity indices allow the infaunal community at each site to be easily
compared with other sites, or, more pertinently, from year to year or survey to survey
27
providing an indication of whether or not diversity is changing through time naturally or as
a result of outside influences.
Table 10.
Diversity indices (H’) for each site at Areas 1804 and 1805, Otago Harbour.
Area
1804
1805
Site Quadrat H'(log e) H'(log e)
1
1
1.768
1.889
1
2
1.003
1.33
1
3
0.95
0.693
1
4
1.33
1.332
1
5
0.562
1.494
1
6
1.494
1.609
1
7
1.055
1.33
1
8
0.693
1.055
1
9
1.332
1.561
1
10
1.33
1.906
2
1
1.314
1.462
2
2
1.242
1.165
2
3
1.733
1.33
2
4
1.561
1.273
2
5
1.475
1.352
2
6
1.834
1.561
2
7
1.733
1.557
2
8
1.011
1.475
2
9
1.55
0.95
2
10
1.748
1.099
3
1
1.379
1.33
3
2
1.16
1.733
3
3
1.165
0.868
3
4
1.034
1.04
3
5
0.995
0.637
3
6
0.937
1.04
3
7
0
1.677
3
8
1.061
1.332
3
9
0.956
0.868
3
10
1.386
1.242
4
1
1.055
0
4
2
1.946
1.895
4
3
1.834
1.55
4
4
1.099
1.055
4
5
0.736
1.609
4
6
1.33
1.386
4
7
1.099
1.332
4
8
1.099
1.255
4
9
1.099
1.213
4
10
0.693
0.95
12.4
Area
1804
1805
Site Quadrat H'(log e) H'(log e)
5
1
1.97
1.242
5
2
1.91
1.494
5
3
2.16
2.025
5
4
2.02
1.04
5
5
1.609
0.5
5
6
2.047
1.82
5
7
2.084
0.693
5
8
2.197
1.04
5
9
0.974
1.055
5
10
1.799
1.55
6
1
1.905
1.494
6
2
1.677
1.494
6
3
1.517
0.937
6
4
1.427
1.71
6
5
1.465
1.841
6
6
1.583
2.139
6
7
1.99
0.953
6
8
1.04
1.525
6
9
1.885
0.637
6
10
2.069
1.33
7
1
1.352
0.637
7
2
1.099
0
7
3
1.55
0
7
4
0.974
0
7
5
1.277
0
7
6
0.637
1.099
7
7
1.04
0
7
8
1.099
1.04
7
9
1.748
0
7
10
0.95
1.332
8
1
0.693
1.011
8
2
1.386
0.974
8
3
1.386
0.637
8
4
1.33
1.213
8
5
1.386
1.303
8
6
1.332
1.56
8
7
0.693
1.04
8
8
0.693
0
8
9
1.792
1.332
8
10
1.561
1.386
Objective 4: Characterisation of the substrate associated with the shellfish areas
Substrate samples were oven dried at 60˚C for 24 hours, then weighed to the nearest
thousandth of a gram. Dried sediment was then sieved for 10 minutes on an Endicott sieve
shaker using sieves with 2mm, 500µm, 250µm and 63µm mesh sizes. At the completion of
shaking each fraction was weighed to give a percentage of the original mass. Fractions were
recombined, reweighed and ashed in a muffle furnace at 550˚C for four hours, then samples
were reweighed and the percentage loss on ashing calculated.
28
Substrate at both areas was generally fine sand with a significant proportion being in the
250µm – 63µm grain size, irrespective of depth (F4,235; p = <0.001 for each depth) (Tables
11, 12 and 13).
Table 11.
Sediment grain sizes for surface substrate at Areas 1804 and 1805, Otago Harbour.
Percentage of dried mass
Area
Site
1a
1b
1c
2a
2b
2c
3a
3b
3c
4a
4b
1804 4c
5a
5b
5c
6a
6b
6c
7a
7b
7c
8a
8b
8c
1a
1b
1c
2a
2b
2c
3a
3b
3c
4a
4b
4c
1805
5a
5b
5c
6a
6b
6c
7a
7b
7c
8a
8b
8c
Depth
2mm500µm- 250µm% Loss on
>2mm >500µm >250µm >63µm <63µm ashing
(mm)
Surface 1.82
4.14
26.60
60.50
6.63
1.00
Surface 8.50
5.82
8.98
70.33
5.84
3.18
Surface 3.77
3.84
11.20
74.59
6.08
2.21
Surface 0.00
0.25
18.66
79.45
1.45
1.57
Surface 1.00
0.79
10.10
85.06
2.53
1.04
Surface 0.27
1.03
32.04
64.01
2.20
1.04
Surface 0.00
0.85
10.54
88.26
0.21
0.89
Surface 0.06
0.32
4.51
94.73
0.30
13.70
Surface 0.00
0.04
5.58
94.63
0.27
0.67
Surface 0.32
0.52
24.02
73.58
1.33
0.51
Surface 2.29
3.53
38.55
54.71
0.98
1.20
Surface 1.32
1.82
36.93
59.21
0.73
0.72
Surface 0.05
0.20
36.13
62.97
0.39
0.79
Surface 1.08
18.46
63.03
14.23
0.03
1.20
Surface 0.03
1.02
10.68
86.53
1.87
0.70
Surface 0.00
0.86
17.43
79.68
1.88
0.66
Surface 0.11
0.83
8.41
89.50
1.21
0.99
Surface 0.04
1.12
9.77
87.80
1.07
0.75
Surface 2.35
0.86
8.16
85.76
2.50
2.02
Surface 0.08
0.27
5.21
94.18
0.35
0.87
Surface 0.00
0.29
3.88
95.08
0.59
1.03
Surface 0.05
1.50
35.27
61.05
1.98
0.99
Surface 0.97
2.89
29.59
64.64
1.68
1.02
Surface 2.28
1.45
11.71
82.77
1.56
0.95
Surface 6.28
1.22
30.73
60.93
0.66
2.89
Surface 0.26
1.55
36.36
64.54
0.84
1.07
Surface 5.34
3.09
39.78
50.61
0.81
1.41
Surface 2.83
0.83
6.76
87.92
1.04
0.85
Surface 0.45
0.97
10.51
86.51
1.24
1.04
Surface 11.44 1.87
5.73
79.57
1.05
1.34
Surface 0.00
0.54
26.28
71.35
1.26
1.01
Surface 0.13
0.87
25.14
72.14
1.66
0.74
Surface 0.39
1.73
19.51
77.40
0.91
0.91
Surface 0.08
2.87
27.35
68.16
1.25
1.04
Surface 27.22
2.47
23.32
46.00
0.86
1.43
Surface 1.27
1.65
19.38
76.37
0.93
1.00
Surface 0.55
0.50
13.57
84.53
0.89
0.86
Surface 1.66
0.38
30.71
66.21
0.76
1.03
Surface 0.34
2.89
45.95
49.14
1.48
0.55
Surface 0.00
1.19
44.89
53.56
0.26
0.80
Surface 0.00
2.02
36.36
61.18
0.26
0.75
Surface 0.01
2.20
24.94
72.53
0.22
0.82
Surface 0.20
0.15
14.32
85.00
0.14
0.57
Surface 0.00
3.23
51.88
44.67
0.10
0.75
Surface 0.11
0.93
55.24
43.58
0.19
8.34
Surface 0.00
1.35
51.53
46.73
0.27
0.55
Surface 0.00
2.19
52.42
44.77
0.22
0.69
Surface 0.02
0.99
37.49
61.08
0.28
0.29
Mean
1.77
1.88
24.94
69.95
1.28
1.47
29
A relatively small percentage of the sediment on each area can be classified as silt
(<63µm) reflecting the disturbed nature of the sediment at these localities. Those sites
with a higher percentage of silt than other sites tended to be those with which Zoestera
areas were associated (e.g. Site 1, Area 1804, Tables 11, 12 and 13). This is not
unexpected as Zoestera reduces current speed on a very localised basis allowing fine
sediments to settle out.
Table 12.
Sediment grain sizes at 100mm depth in substrate at Areas 1804 and 1805, Otago Harbour.
Area
1804
1805
Site
1a
1b
1c
2a
2b
2c
3a
3b
3c
4a
4b
4c
5a
5b
5c
6a
6b
6c
7a
7b
7c
8a
8b
8c
1a
1b
1c
2a
2b
2c
3a
3b
3c
4a
4b
4c
5a
5b
5c
6a
6b
6c
7a
7b
7c
8a
8b
8c
Depth
(mm)
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
Mean
2mm500µm>2mm >500µm >250µm
3.53
0.53
5.80
0.03
4.17
15.07
1.35
1.33
6.30
5.70
2.61
10.81
12.66 3.06
7.18
11.45 4.34
6.41
0.03
2.05
2.36
0.13
0.37
16.78
0.12
0.30
1.96
6.95
3.02
8.50
22.61 3.55
20.12
10.30 3.34
8.90
3.03
2.47
19.68
2.01
1.17
23.62
2.40
1.16
1.06
0.09
2.04
11.34
0.03
1.19
16.09
0.02
0.88
18.12
0.71
1.87
20.51
2.40
1.48
0.54
0.69
1.54
4.72
11.17 3.58
4.07
6.91
2.57
8.95
3.45
2.14
5.10
3.41
10.73
43.28
13.75 0.64
9.29
3.13
1.94
23.81
19.02 1.45
5.85
7.04
1.17
13.09
1.45
1.04
7.34
0.09
2.02
25.53
0.05
1.26
7.50
0.14
1.82
21.99
0.57
1.77
7.91
0.00
1.36
10.96
0.79
1.44
11.99
0.06
1.71
56.40
0.00
1.36
33.22
0.78
1.02
42.24
0.11
0.20
43.96
1.89
0.46
11.93
1.53
1.04
33.23
0.00
0.14
42.90
0.43
0.62
43.65
0.00
0.60
39.89
0.98
0.62
49.56
0.48
0.24
25.82
1.28
0.86
30.72
3.43
1.80
18.46
250µm% Loss on
>63µm <63µm ashing
86.53
2.94
1.02
77.05
3.47
1.42
88.15
2.12
1.53
78.16
1.80
0.85
75.25
1.48
1.01
76.43
1.54
1.15
95.15
0.23
0.67
82.45
0.19
0.69
97.49
0.19
0.61
81.42
0.72
1.06
52.79
0.87
0.99
76.48
1.30
0.73
73.54
1.10
0.68
71.49
1.76
1.04
84.67
0.91
0.80
85.72
0.83
0.75
81.89
0.77
0.95
80.19
0.77
0.68
76.33
0.47
0.86
90.03
0.62
0.92
92.02
0.86
0.86
80.29
0.91
1.30
81.01
0.53
0.91
88.29
0.89
0.96
39.86
0.16
1.36
75.54
0.64
0.90
70.42
0.72
1.09
72.82
0.74
1.04
77.18
0.69
0.98
88.51
0.88
0.77
71.28
0.67
0.92
91.69
0.82
0.78
75.43
0.68
0.81
88.76
1.22
0.98
86.78
0.81
0.89
84.31
1.54
1.17
41.20
0.42
1.27
64.42
0.66
1.18
55.33
0.64
0.85
55.23
0.41
0.65
85.44
0.28
0.67
64.16
0.14
0.65
56.93
0.10
0.35
55.17
0.14
0.23
59.33
0.15
0.45
48.92
0.15
0.66
73.47
0.22
0.31
65.59
0.21
0.77
75.01
0.84
0.88
Ashing generally produced a relatively small reduction in overall mass, indicating
that the amount of organic material within the substrate is quite low (Tables 11,
30
12 and 13). In samples 3b at the surface of Area 1804 and 8b at 200mm depth in
Area 1804, however, there was considerable loss of mass due to ashing. This
suggests that there was some reasonably large body of organic matter in each of
these samples, perhaps a piece of wood or macroalgae.
Table 13.
Sediment grain sizes at 200mm depth in substrate at Areas 1804 and 1805, Otago Harbour.
Area
1804
1805
Site
1a
1b
1c
2a
2b
2c
3a
3b
3c
4a
4b
4c
5a
5b
5c
6a
6b
6c
7a
7b
7c
8a
8b
8c
1a
1b
1c
2a
2b
2c
3a
3b
3c
4a
4b
4c
5a
5b
5c
6a
6b
6c
7a
7b
7c
8a
8b
8c
Depth
2mm500µm(mm) >2mm >500µm >250µm
200
0.31
1.86
4.96
200
0.68
1.27
4.14
200
1.43
2.96
10.59
200
3.13
2.83
7.40
200
8.49
3.81
10.49
200
3.19
1.20
4.01
200
5.52
1.45
2.03
200
4.11
2.00
5.95
200
3.88
1.69
5.01
200
1.32
1.70
22.87
200
2.39
1.87
22.55
200
1.99
3.71
8.78
200
0.97
1.13
13.93
200
0.33
2.80
21.59
200
0.53
3.39
24.20
200
0.65
2.31
32.90
200
0.31
3.60
27.43
200
0.48
1.32
30.74
200
1.36
1.72
2.78
200
4.11
1.50
4.47
200
7.62
2.52
2.51
200
4.97
5.24
8.74
200 12.56 7.39
5.65
200
8.96
4.98
11.41
200
6.75
0.77
30.36
200
0.68
2.41
56.08
200
0.99
1.60
13.72
200 15.56 1.32
13.33
200
8.00
0.82
12.20
200 10.00 2.64
7.32
200
2.50
0.41
87.88
200
5.31
0.53
14.36
200
0.98
1.53
10.06
200
0.15
1.75
7.92
200
0.20
0.97
17.12
200
0.15
0.24
13.92
200
0.30
1.91
34.97
200
0.43
0.34
4.82
200
0.19
1.49
50.85
200
0.24
0.31
43.21
200
0.50
0.41
19.44
200
2.46
0.55
7.00
200
0.05
0.85
36.20
200
0.03
0.06
39.56
200
0.10
0.09
26.95
200
0.14
1.35
47.89
200
0.00
1.59
22.14
200
0.00
0.13
43.01
Mean 2.81
1.84
19.91
250µm% Loss on
>63µm <63µm ashing
90.76
2.08
1.00
91.32
2.58
1.23
83.16
1.74
1.21
83.96
2.39
1.04
75.37
1.58
1.18
88.34
3.09
0.91
90.50
0.44
1.10
87.40
0.36
0.77
88.99
0.33
0.87
73.50
0.47
0.64
72.43
0.63
0.85
84.66
0.71
0.74
81.90
1.66
1.05
73.61
1.79
0.87
70.03
1.77
1.19
63.31
0.69
0.74
67.73
0.93
1.09
66.97
0.78
1.03
93.33
0.50
0.81
89.10
0.56
0.99
86.56
0.54
0.98
80.28
0.58
0.57
73.71
0.74
18.94
73.93
0.47
1.06
61.28
0.68
0.57
40.04
0.57
0.78
82.87
0.64
0.88
68.80
0.72
1.04
78.25
0.62
0.97
79.37
0.61
1.05
9.06
0.12
1.28
78.57
1.14
0.95
86.82
1.26
0.84
89.30
0.78
0.82
80.88
0.72
0.71
84.31
1.15
0.67
62.32
0.66
0.86
93.62
0.54
0.60
47.11
0.41
0.65
56.14
0.17
0.56
79.34
0.19
0.53
90.27
0.71
1.03
62.57
0.17
1.19
60.36
0.15
0.42
72.80
0.13
0.53
50.39
0.25
0.34
75.65
0.00
0.66
56.77
0.26
0.57
74.54
0.83
1.24
Representative cores at each site were photographed and the depth of the redox
discontinuity layer measured (Table 14) (Appendix 5). The sulphurous smell
31
usually associated with anoxic sediments was generally mild for all of the
sampled cores.
Table 14.
Depth of the redox discontinuity layer for each core.
Area
1804
1805
13.
Site/Core
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Depth of RDL
(mm)
50
60
80
40
35
55
70
20
40
65
40
35
35
30
65
Thickness of RDL
(mm)
60
75
>120
70
75
>180
>170
160
>150
>160
110
70
120
>180
>180
Description
of RDL
Diffuse
Distinct
Distinct
Diffuse
Diffuse
Absent
Distinct
Distinct
Distinct
Distinct
Distinct
Distinct
Diffuse
Distinct
Distinct
Distinct
Discussion and Management Implications
This survey is an initial survey before any experimental harvesting takes place. It should,
therefore, be considered a baseline survey that aims to establish the virgin biomass of clams
at Areas 1804 and 1805 within Otago Harbour. The biomass of clams per unit area is not
dissimilar to beds in Waitati Inlet (Table 15) and one would assume that the areas should
sustain a similar relative harvest effort as is being applied at Waitati Inlet.
A repeat survey of impact (harvested) and control (non harvested) areas after the initial
harvest and again at 3 and 5 year intervals will show how harvesting is impacting on both
biomass of clams at each area and any impacts on size/frequency distributions.
Table 15.
Biomass of clams per unit area in Waitati Inlet and at Areas 1804 and 1805 in Otago Harbour.
Data for Waitati Inlet from Stewart 2008.
Bed
Locality
300
Waitati Inlet
B
Waitati Inlet
C
Waitati Inlet
D
Waitati Inlet
E
Waitati Inlet
G
Waitati Inlet
O
Waitati Inlet
R
Waitati Inlet
1804 Otago Harbour
1805 Otago Harbour
Density (kg/m2)
0.9
6.0
6.9
8.7
6.2
7.1
5.7
8.9
7.3
7.6
This initial survey has included an assessment of the benthic communities associated with
each of the proposed clam harvesting areas and characterisation of the substrate at three
depths on each area. The infaunal communities are typical of infaunal sandy shore
communities in sheltered inlets and harbours around most of New Zealand (Morton and
32
Miller 1973) and the invertebrate assemblages encountered show little difference from those
in previous studies within Otago Harbour (e.g. Ralph and Yaldwyn 1956, Rainer 1980,
Grove 1995). It is, therefore, reasonable to expect that these assemblages will remain
essentially unchanged for the next survey, unless harvesting has some discernible impact on
the communities. As for clam biomass, the next survey should reveal if there are in fact any
impacts.
The same applies to substrate. This is generally fine sand with little in the way of large
particles or silt. Large particles, where they occur, tend to be dead shell. Harvesting may
have some impact on the depth distribution of particles and may have an effect on the depth
of the redox discontinuity layer (RDL) at harvested sites. However, it is expected that there
will be a lengthy gap (2-3 years) between harvesting runs at any particular site and this
should allow sediment and RDL profiles to re-establish between harvests.
14.
Conclusions
As already stated, this is a baseline survey and as such, has reported the current state of the
unharvested areas and their associated benthic communities. It is hoped that repeated
surveys conducted in impact and control areas in future years will shed some light on
whether or not there are any significant impacts on either area as a result of harvesting and if
the experimental harvest regime is sustainable.
Acknowledgements
Ryder Consulting Limited would like to acknowledge the assistance of the following
people and organisations:
Graeme Grainger, Dana Clark, Georgina Pickerell, Jess Ericson and Southern Clams Ltd.
33
15.
References
Annala, J.H., Sullivan, K.J. (1996). Report from the mid-year Fishery Assessment Plenary,
November 1996: stock assessments and yield estimates. Ministry of Fisheries.
Annala, J.H., Sullivan, K.J., O’Brien, C.J., Smith, N.W.McL. and Grayling, S.M. (2003). Report
from the Fishery Assessment Plenary, May 2003: stock assessments and yield estimates.
Ministry of Fisheries.
Bates, C.R., Scott, G., Tobin, M. and Thompson, R. (2007). Weighing the cost and benefits of
reduced sampling resolution in biomonitoring studies: Perspectives from the temperate rocky
intertidal. Biological Conservation 137(4): 617-625.
Boyd, R.O. and Reilly J.L. (2004). 1999/2000 National marine Recreational Fishing Survey:
harvest estimates. Draft New Zealand Fisheries Assessment Report.
Bradford, E. (1998). Harvest estimates from the 1996 national recreational fishing surveys. N.Z.
Fisheries Assessment Research Document. 98/16. 27 p.
Breen P. A., Carbines, G. C. and Kendrick, T. H. (1999). Stock assessment of cockles in Papanui
and Waitati Inlets, Otago Harbour, and Purakanui, Otago. Final Report for the Ministry of
Fisheries research project COC9701 dated July 1999.
Cryer, M. (1997). Assessment of cockles from Snake bank, Whangarei Harbour, for 1996. New
Zealand Fisheries Assessment Research document 97/2.
Francis, R.I.C.C. (1984). An adaptive strategy for stratified random trawl surveys. N.Z. Journal of
Marine and Freshwater Research 18: 59-71.
Grove, S.L. (1995). Subtidal soft-bottom macrofauna of the upper Otago Harbour. Unpublished MSc
thesis, University of Otago.
Hilborn, R. and Walters, C.J. (1992). Quantitative Fisheries Stock Assessment: Choice, dynamics
and uncertainty. Chapman and Hall, London.
Irwin, C.R. (1999). The effects of harvesting on the reproductive and population biology of the
New Zealand Littleneck Clam (Austrovenus stutchburyi) in Waitati Inlet. Unpublished Msc
thesis, University of Otago, Dunedin, New Zealand.
Kingsford, M. and Battershill, C. 1998. Studying temperate marine environments: A handbook for
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molluscs. Unpublished PhD thesis, University of Auckland. pp 250.
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multiple populations at multiple locations. N.Z. journal of Marine and Freshwater Research
36: 581-591.
Martin, N.D. (1984). Chione stutchburyi population responses to exploitation. MSc thesis.
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34
Morton, J. and Miller M. (1973). The New Zealand Sea Shore. Collins, Auckland. 653 pp.
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Zealand. N.Z. Oceanographic Inst. Memoir 80: 38pp.
Ralph, P.M. and Yaldwyn, J.C. (1956). Seafloor animals from the region of Portobello Marine
Biological Station, Otago Harbour. Tuatara 6(2): 57-85.
Stewart, B., Keogh, J., Fletcher, D. and Mladenov, P. (1992). Biomass survey of the New Zealand
littleneck clam (Chione stutchburyi) in Papanui and Waitati Inlets, Otago during 1991/1992.
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37p.
Stewart, B. (2006). Stock assessment of cockles (Austrovenus stutchburyi) in Papanui and Waitati
Inlets, Otago 2004. Final report for the Ministry of Fisheries Research Project COC2004/02.
54p.
Stewart, B. (2008). Stock assessment of clams (Austrovenus stutchburyi) in Waitati Inlet, Otago
2007. Report prepared for Southern Clams Ltd by Ryder Consulting. 25p.
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35
Appendix 1
Raw data – Area 1804
Site
Weight
281
656.7
1251
1739.1
111
112
1269.0
1870.8
282
283
761.9
706.2
1252
1253
1566.6
1670.9
113
121
122
1638.1
2073.4
1283.5
291
292
293
770.7
677.8
703.4ß
1261
1262
1263
715.9
865.6
804.1
123
131
132
2094.4
2109.3
1089.0
1101
1102
1103
964.2
1996.3
1718.0
1271
1272
1273
410.9
883.8
222.7
133
141
1283.5
497.1
1111
1112
1160.4
871.6
1281
1282
0.0
2242.3
142
143
144
0.0
922.7
315.6
1113
1121
1122
1198.6
840.5
807.4
1283
1284
1291
2337.3
2093.2
1232.6
151
152
153
0.0
0.0
0.0
1123
1131
1132
422.1
2557.2
0.0
1292
1293
1301
926.9
963.5
1214.0
161
162
787.4
324.5
1133
1134
1688.8
0.0
1302
1303
1453.4
684.0
163
171
172
478.9
1248.9
1216.0
1135
1141
1142
0.0
1645.7
1406.0
1311
1312
1313
1045.2
412.3
684.3
173
181
182
1041.7
0.0
0.0
1143
1151
1152
1500.5
1204.8
748.2
1321
1322
1323
789.4
531.1
299.4
183
184
0.0
0.0
1153
1161
1148.2
714.0
1331
1332
1035.2
997.1
191
192
193
46.3
1643.8
2080.7
1162
1163
1171
885.9
1410.6
74.9
1333
1341
1342
707.7
710
765.1
194
195
211
1486.6
1919.7
1468.3
1172
1173
1174
0.0
0.0
0.2
1343
1351
1352
668.6
33.0
419.9
212
213
129.5
515.9
1181
1182
1814.4
2043.4
1353
1354
0.0
225.8
214
221
222
141.9
1.5
8.6
1183
1191
1192
2135.9
1512.1
2080.9
1355
1361
1362
188.2
1433.1
1288.2
223
231
232
0.0
870.7
473.4
1193
1201
1202
1835.9
928.3
1032.9
1363
1371
1372
638.1
1120.5
339.2
233
241
684.4
25.8
1203
1211
1140.5
765.8
1373
2101
852.6
405.7
242
243
251
813.3
742.9
610.9
1212
1213
1221
668.7
1028.8
559.4
2102
2103
2111
278.5
174.4
331.3
252
253
261
665.4
614.1
702.7
1222
1223
1231
712.9
1080.1
0.0
2112
2113
353.1
203.7
262
263
497.7
673.9
1232
1234
2032.4
2148.1
271
272
273
1021.7
975.1
875.9
1241
1242
1243
1997.7
1566.3
1677.1
36
Site
111
Weight
988.1
291
292
2110.1
1849.2
2111
2112
1871.8
1707.5
112
113
121
1464
946
47.6
293
1101
1102
1180.4
2340.5
564.5
2113
2121
2122
1500.6
1090.8
1403.6
122
123
124
1413.5
1427.5
1777
1103
1111
1112
1366.1
184.3
1383.9
2123
2131
2132
1191
836.2
596.8
131
132
1480.1
991.8
1113
1114
492.0
335.6
2133
2141
556.1
752.9
133
141
142
864.6
666.1
304.8
1121
1122
1123
0.0
46.6
312.8
2142
2143
2144
0.0
0.0
193.2
143
151
152
204.1
271.2
244.8
1124
1131
1132
37.7
812.3
603.5
2145
2146
2151
0.0
0.0
0.0
153
161
232.0
416.4
1133
1141
493.1
1291.3
2152
2153
0.0
0.0
162
163
171
95.1
268.5
499.1
1142
1143
1151
2071.2
393.2
1354
2161
2162
2163
245.9
0
0
172
173
181
295.9
493.5
463.7
1152
1153
1161
1462.6
641.1
499.9
2164
2165
2171
263.4
82.4
0
182
183
324.5
23.6
1162
1163
1711.7
1669
2172
2173
312.7
134
184
191
192
369.1
195
207.9
1171
1172
1173
1219.7
1493.1
1716.6
2174
2181
2182
365.5
190.3
0
193
211
212
605.3
1513.8
1132.4
1181
1182
1183
485.8
346.1
0
2183
2184
2191
258.4
237.4
0
213
221
1012.6
561
1184
1191
759.7
93.3
2192
2193
37
373.1
222
223
231
649.8
636.6
477.7
1192
1193
1194
641.9
15.5
1768.0
2194
2195
388.3
60.0
232
233
234
1547.2
944.2
1295.1
1201
1202
1203
1284.5
907.7
887.2
241
242
1732
102.1
1211
1212
70.4
1313.0
243
244
245
1370.9
0.0
457.4
1213
1214
1221
1097.5
390
1391.0
246
251
84.6
1010.5
1222
1223
36.5
19
252
253
261
892
545
354
1224
1231
1232
30.8
150.6
911.6
262
263
271
562.2
489.8
339.9
1233
1234
1241
339.2
650.5
0
272
273
47
1418.9
1242
1243
39.1
454.1
274
281
282
1977.8
153.9
929.1
1244
2101
2102
92.3
1924.5
356.2
283
901.4
2103
1936.4
37
Appendix 1
Site
Weight
281
656.7
1251
1739.1
111
112
1269.0
1870.8
282
283
761.9
706.2
1252
1253
1566.6
1670.9
113
121
122
1638.1
2073.4
1283.5
291
292
293
770.7
677.8
703.4ß
1261
1262
1263
715.9
865.6
804.1
123
131
132
2094.4
2109.3
1089.0
1101
1102
1103
964.2
1996.3
1718.0
1271
1272
1273
410.9
883.8
222.7
133
141
1283.5
497.1
1111
1112
1160.4
871.6
1281
1282
0.0
2242.3
142
143
144
0.0
922.7
315.6
1113
1121
1122
1198.6
840.5
807.4
1283
1284
1291
2337.3
2093.2
1232.6
151
152
153
0.0
0.0
0.0
1123
1131
1132
422.1
2557.2
0.0
1292
1293
1301
926.9
963.5
1214.0
161
162
787.4
324.5
1133
1134
1688.8
0.0
1302
1303
1453.4
684.0
163
171
172
478.9
1248.9
1216.0
1135
1141
1142
0.0
1645.7
1406.0
1311
1312
1313
1045.2
412.3
684.3
173
181
182
1041.7
0.0
0.0
1143
1151
1152
1500.5
1204.8
748.2
1321
1322
1323
789.4
531.1
299.4
183
184
0.0
0.0
1153
1161
1148.2
714.0
1331
1332
1035.2
997.1
191
192
193
46.3
1643.8
2080.7
1162
1163
1171
885.9
1410.6
74.9
1333
1341
1342
707.7
710
765.1
194
195
211
1486.6
1919.7
1468.3
1172
1173
1174
0.0
0.0
0.2
1343
1351
1352
668.6
33.0
419.9
212
213
129.5
515.9
1181
1182
1814.4
2043.4
1353
1354
0.0
225.8
214
221
222
141.9
1.5
8.6
1183
1191
1192
2135.9
1512.1
2080.9
1355
1361
1362
188.2
1433.1
1288.2
223
231
232
0.0
870.7
473.4
1193
1201
1202
1835.9
928.3
1032.9
1363
1371
1372
638.1
1120.5
339.2
233
241
684.4
25.8
1203
1211
1140.5
765.8
1373
2101
852.6
405.7
242
243
251
813.3
742.9
610.9
1212
1213
1221
668.7
1028.8
559.4
2102
2103
2111
278.5
174.4
331.3
252
253
261
665.4
614.1
702.7
1222
1223
1231
712.9
1080.1
0.0
2112
2113
353.1
203.7
262
263
497.7
673.9
1232
1234
2032.4
2148.1
271
272
273
1021.7
975.1
875.9
1241
1242
1243
1997.7
1566.3
1677.1
38
Site
111
Weight
988.1
291
292
2110.1
1849.2
2111
2112
1871.8
1707.5
112
113
121
1464
946
47.6
293
1101
1102
1180.4
2340.5
564.5
2113
2121
2122
1500.6
1090.8
1403.6
122
123
124
1413.5
1427.5
1777
1103
1111
1112
1366.1
184.3
1383.9
2123
2131
2132
1191
836.2
596.8
131
132
1480.1
991.8
1113
1114
492.0
335.6
2133
2141
556.1
752.9
133
141
142
864.6
666.1
304.8
1121
1122
1123
0.0
46.6
312.8
2142
2143
2144
0.0
0.0
193.2
143
151
152
204.1
271.2
244.8
1124
1131
1132
37.7
812.3
603.5
2145
2146
2151
0.0
0.0
0.0
153
161
232.0
416.4
1133
1141
493.1
1291.3
2152
2153
0.0
0.0
162
163
171
95.1
268.5
499.1
1142
1143
1151
2071.2
393.2
1354
2161
2162
2163
245.9
0
0
172
173
181
295.9
493.5
463.7
1152
1153
1161
1462.6
641.1
499.9
2164
2165
2171
263.4
82.4
0
182
183
324.5
23.6
1162
1163
1711.7
1669
2172
2173
312.7
134
184
191
192
369.1
195
207.9
1171
1172
1173
1219.7
1493.1
1716.6
2174
2181
2182
365.5
190.3
0
193
211
212
605.3
1513.8
1132.4
1181
1182
1183
485.8
346.1
0
2183
2184
2191
258.4
237.4
0
213
221
1012.6
561
1184
1191
759.7
93.3
2192
2193
37
373.1
222
223
231
649.8
636.6
477.7
1192
1193
1194
641.9
15.5
1768.0
2194
2195
388.3
60.0
232
233
234
1547.2
944.2
1295.1
1201
1202
1203
1284.5
907.7
887.2
241
242
1732
102.1
1211
1212
70.4
1313.0
243
244
245
1370.9
0.0
457.4
1213
1214
1221
1097.5
390
1391.0
246
251
84.6
1010.5
1222
1223
36.5
19
252
253
261
892
545
354
1224
1231
1232
30.8
150.6
911.6
262
263
271
562.2
489.8
339.9
1233
1234
1241
339.2
650.5
0
272
273
47
1418.9
1242
1243
39.1
454.1
274
281
282
1977.8
153.9
929.1
1244
2101
2102
92.3
1924.5
356.2
283
901.4
2103
1936.4
39
Appendix 2
Area 1804 Sites
1.
2.
40
3.
4.
41
5.
6.
42
7.
8.
43
Area 1805.
1.
2.
44
3.
4.
45
5.
6.
46
7.
8.
47
Appendix 3
Quadrats – Area 1804.
1.
2.
3.
4.
5.
6.
48
7.
8.
Quadrats, Area 1805.
1.
2.
3.
4.
49
5.
6.
7.
8.
50
Appendix 4
Invertebrate Raw Data
Area 1804
8-Apr-08
Phylum
Family
Polychaeta
Arenicolidae
Capitellidae
Glyceridae
Lumbrineridae
Nephtyidae
Nereidae
Opheliidae
Oweniidae
Pectinariidae
Spionidae
Syllidae
Terebellidae
Crustacea Malacostraca
Amphipoda
Isopoda
Cumacea
Ostracoda
Mollusca Gastropoda
Bivalvia
Location
Site 1
Site 2
Site 3
Site 4
Sample Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10
Genus/species
1
1
2
1
1
1
1
1
3
1
1
3
2
1
1
2
1
1
1
6
3
3
2
1
2
1
2
1
3
3
2
1
1
1
2
3
2
1
3
1
1
1
1
1
1
2
1
1
1
1
1
3
8
8
1
1
17
2
1
2
5
1
9
2
4
2
4
1
1
1
1
1
1
1
1
1
1
4
2
1
1
6
2
2
1
2
1
3
1
3
2
1
1
1
1
1
1
1
3
1
Mactridae
Tellinidae
Solemyidae
1
1
1
Isocladus armatus
Trochidae
Veneridae
1
1
Halicarcinus spp
Gamaridae
Haustoriidae
Lysianassidae
Oedicerotidae
Phoxocephalidae
Acmaeidae
Batilliidae
Cominellidae
Trochidae
1
Notoacmea spp
Diloma subrostrata
Tawera spissa
Puyseguria spp
Macomona liliana
Solemya parkinsoni
6
1
1
2
2
1
1
1
1
2
1
3
2
1
1
1
1
2
1
2
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
3
1
11
1
2
2
3
1
2
1
1
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
51
Area 1804
8-Apr-08
Phylum
Family
Polychaeta
Arenicolidae
Capitellidae
Glyceridae
Lumbrineridae
Nephtyidae
Nereidae
Opheliidae
Oweniidae
Pectinariidae
Spionidae
Syllidae
Terebellidae
Crustacea Malacostraca
Amphipoda
Isopoda
Cumacea
Ostracoda
Mollusca Gastropoda
Bivalvia
Location
Site 5
Site 6
Site 7
Site 8
Genus/species
2
1
5
1
2
6
1
2
2
2
1
2
1
1
1
2
3
3
1
1
1
4
1
1
3
4
2
1
4
1
1
1
1
1
1
1
1
2
1
3
2
1
2
1
1
1
3
3
1
1
1
2
4
2
2
3
1
3
1
1
2
1
1
1
1
2
1
1
1
3
1
6
2
2
3
2
1
1
1
1
1
1
1
1
2
Halicarcinus spp
Gamaridae
Haustoriidae
Lysianassidae
Oedicerotidae
Phoxocephalidae
1
1
3
1
1
2
1
3
2
1
1
1
4
1
1
1
2
2
1
3
Isocladus armatus
1
1
2
6
6
1
2
4
4
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
7
2
3
8
3
6
2
3
2
2
1
2
2
1
1
1
Acmaeidae
Batilliidae
Cominellidae
Trochidae
Trochidae
Veneridae
Mactridae
Tellinidae
Solemyidae
Notoacmea spp
Diloma subrostrata
Tawera spissa
Puyseguria spp
1
3
1
2
3
2
1
1
4
1
1
1
1
1
1
2
1
1
1
1
1
1
1
3
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
1
2
3
2
1
1
1
1
1
1
2
1
1
Macomona liliana
Solemya parkinsoni
1
1
1
1
1
2
1
1
1
1
1
1
1
1
52
Area 1805
7-Apr-08
Phylum
Family
Polychaeta
Arenicolidae
Glyceridae
Lumbrineridae
Nephtyidae
Nereidae
Nereididae
Opheliidae
Oweniidae
Pectinariidae
Sabellidae
Spionidae
Terebellidae
Crustacea
Malacostraca
Amphipoda
Mollusca
Isopoda
Tanaidacea
Cumacea
Ostracoda
Gastropoda
Bivalvia
Location
Site 1
Site 2
Site 3
Site 4
Genus/species
2
2
1
3
1
1
1
2
1
1
2
1
1
1
2
1
1
2
2
1
2
1
Halicarcinus spp
Periclimenes batei
Callianassa filholi
Palaemonidae
Callianassidae
Gamaridae
Haustoriidae
Phoxocephalidae
Talorchestia spp
Talitridae
Isocladus armatus
2
1
1
1
1
2
1
1
6
1
8
1
3
2
11
1
2
1
1
1
1
2
1
3
1
4
2
1
2
3
2
2
2
4
2
2
1
1
1
2
4
1
1
3
3
5
1
2
2
5
1
1
1
1
3
1
1
4
1
1
3
1
1
1
1
1
1
4
1
1
1
4
3
1
2
1
1
1
1
1
2
1
2
1
1
3
2
2
1
2
1
1
1
1
1
Acmaeidae
Veneridae
Mactridae
Tellinidae
Solemyidae
Notoacmea spp
Puyseguria spp
Macomona liliana
Solemya parkinsoni
2
1
1
1
1
1
1
1
2
1
2
1
1
1
1
3
1
1
2
1
2
1
2
2
3
2
2
1
1
2
1
1
2
2
1
1
1
1
1
1
2
1
2
5
1
1
1
4
1
1
1
1
1
2
53
Area 1805
7-Apr-08
Phylum
Family
Polychaeta
Arenicolidae
Glyceridae
Lumbrineridae
Nephtyidae
Nereidae
Nereididae
Opheliidae
Oweniidae
Pectinariidae
Sabellidae
Spionidae
Terebellidae
Crustacea
Malacostraca
Amphipoda
Mollusca
Isopoda
Tanaidacea
Cumacea
Ostracoda
Gastropoda
Bivalvia
Location
Site 5
Site 6
Site 7
Site 8
Genus/species
3
2
1
1
3
1
1
1
1
3
1
1
1
3
1
1
4
1
1
1
1
1
1
2
2
2
1
2
1
3
1
1
2
2
1
1
3
1
1
1
1
2
1
2
1
1
2
4
5
1
2
3
4
Mactridae
Tellinidae
Solemyidae
1
1
1
2
1
Halicarcinus spp
Periclimenes batei
Callianassa filholi
1
1
1
3
1
1
2
1
2
2
4
3
1
1
1
3
1
2
1
3
1
1
2
9
1
1
4
2
2
6
1
2
2
1
2
10
1
6
2
1
2
2
1
1
1
2
1
1
2
1
1
1
1
1
1
1
Veneridae
2
1
Palaemonidae
Callianassidae
Gamaridae
Haustoriidae
Phoxocephalidae
Talorchestia spp
Talitridae
Isocladus armatus
Acmaeidae
1
1
1
1
2
Notoacmea spp
Puyseguria spp
Macomona liliana
Solemya parkinsoni
1
1
1
1
1
1
2
1
2
2
1
2
2
1
3
1
3
1
1
2
1
1
1
2
1
1
54
Appendix 5. Cores
Area 1804.
Site 1
Site 3
Site 5
Site 7
Site 2
Site 4
Site 6
Site 8
55
Area 1805
Site 1
Site 2
Site 3
Site 4
Site 5
Site 7
Site 6
Site 8

2008 Harbour Clam Baseline, Resource and Habitat Survey

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