Gillnetting Survey of the Lake Kaniere Sports
fishery.
Rhys Adams - Fish & Game Officer
March 2015
Summary
Lake Kaniere was surveyed in January 2015 to assess the success of enhancement
releases that have occurred over recent years in Lake Kaniere. The Lake was surveyed
using the same method in 2006 prior to any recent enhancement releases occurring
therefore some comparisons are made between the populations surveyed.
9 brown trout, 4 rainbow trout and 67 perch were caught and measured on 6 mornings
during January. No salmon were caught in the survey. Brown trout averaged 856
grams, were 422 mm in length and had a condition factor of 1.14. Rainbow trout
averaged 923 grams, were 459 mm in length and had a condition factor condition
factor of 0.95. Perch averaged 235 gram, and were 248 mm long with a condition factor
of 1.46.
Compared to 2006, brown trout are smaller and less abundant, but are no different in
condition. Brown trout condition is considered good. Compared to 2006 perch are
smaller, have a lower condition factor, and are in similar abundance.
This is the first time rainbow trout have been caught in a gillnetting survey in Lake
Kaniere therefore their presence is likely to be the result of enhancement releases in
recent years. The survey methodology is suitable for capturing rainbow trout but not
salmon.
Staff recommend to continue to release rainbow and brown trout into Lake Kaniere.
Introduction
Lake Kaniere is unique among West Coast lakes as it currently has a population of brown trout,
rainbow trout, Chinook salmon and red-finned perch. Rainbow trout have been present in the lake
historically and are present in the Hokitika catchment (Kelly, 2006). Salmon are also present in the
catchment.
The inflowing tributary streams of Lake Kaniere provide for limited recruitment for trout and salmon
due to their small size and flood prone nature limiting spawning success. Additionally, hydroelectric
power scheme weirs and structures on the lake’s outlet river form barriers to sports fish migration
into the lake from the Hokitika River catchment. For these reasons Fish & Game enhances the fishery
for anglers by releasing sports fish. Trustpower, the owner of the hydroelectric scheme also supports
the enhancement programme with funding to mitigate the effects of the hydroelectric scheme
structures on sports fish migration.
Gillnetting Survey of Lake Kaniere Sports fishery
Page 1 of 6
This gillnetting survey is designed to take a ‘snapshot’ of the present Lake Kaniere sports fish
population to provide information that can assist Fish & Game in assessing the effectiveness of
sports fish enhancement releases conducted between 2009 and 2014. Table 1 list all recent releases.
Table 1. Sports fish releases at Lake Kaniere 2009-2014
Year Location
Number Size
Species
2009 Geologist Creek
2500
25g
Rainbow Trout
2010 Geologist Creek
8000
7g
Quinnat Salmon
2011 Geologist Creek
4000
17g
Rainbow Trout
2012 Geologist Creek
950
108g
Rainbow Trout
2012 Geologist Creek
900
115g
Rainbow Trout
2012 Hans Bay
5,000
80
Quinnat Salmon
2012 Sunny Bight
50
600g
Rainbow Trout
2012 Sunny Bight
50
500g
Quinnat Salmon
2012 Geologist Creek
5,000
14g
Rainbow Trout
2013 Sunny Creek
5,000
15g
Rainbow Trout
2013 Sunny Bight
120
1kg
Rainbow Trout
2013 Sunny Bight
90
1kg
Rainbow Trout
2014 Sunny Bight
50
1-2kg
Rainbow Trout
2014 Sunny Bight
10
1kg
Quinnat Salmon
2014 Sunny Creek
5,000
6g
Brown Trout
Spawning surveys have been undertaken by Fish & Game staff intermittently throughout the sports
fish spawning season in Lake Kaniere tributary streams between 2011 and 2014. The surveys are
undertaken to monitor if spawning activity is occurring as a result of the enhancement releases
listed in Table 1. The surveys reveal that rainbow trout are spawning in Geologist Creek on an annual
basis, and have been observed spawning in Sunny Creek but to a lesser extent. The highest count of
rainbows observed in Geologist Creek on a spawning survey was 31, in October 2011. Only one dead
salmon has been observed in Geologist creek during the spawning surveys.
The most recent gillnetting survey undertaken in Lake Kaniere was in January 2006. No rainbow
trout or salmon were captured in this survey. The 2006 data provides another ‘snap shot’ of the
brown trout and perch population in Lake Kaniere approximately 3 years before recent
enhancement efforts therefore it is appropriate to compare the data sets to ascertain any
differences in the make-up of the sports fish populations pre and post enhancement. The release of
thousands of sports fish into the lake has the potential to increase competition between species for
food sources and spawning grounds therefore information for brown trout and perch has been
presented in this report.
Survey Method
Three sizes of sinking monofilament gill net were used with stretched mesh sizes of 115mm or 4.62”
(3 nets), 87mm or 3.5” (3 nets), and 70mm or 2.5” (3 nets). The 20m nets were set with one end
attached to the shore and positioned at tangents to the shoreline. The placement of the nets means
that only shoreline habitat is surveyed.
Gillnetting Survey of Lake Kaniere Sports fishery
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Net sites were chosen during previous surveys and repeated. And additional 9 net sites were chosen
by placing 3 sets of three 3 nets in areas with ‘gaps’ in lake edge coverage. GPS coordinates were
recorded for future replication of sites.
The nets were set for 2-4hrs at first light to avoid net saturation and decrease variability in the
method. The month of January was netted to replicate 2006 survey timing and avoid any variation in
the time of year.
Each fish caught was weighed to the nearest 5gms using electronic scales and measured (fork
length) to the nearest 5mm. Healthy fish were returned immediately to the water while dead fish
were retained and gut content identification.
Condition factor was calculated using the formula:
CF = W * 100,000
L*L*L
Where CF is condition factor, W is weight in grams and L is the fork length in millimetres.
Catch per unit effort (CPUE) was calculated for each net size and expressed as catch per 100m net
per hour.
Data was compared statistically using a one way ANOVA. Probability (P) values are given for all
analyses and significant differences noted where values are below 0.05 (95% Confidence).
Results
Sports fish characteristics of Lake Kaniere in 2015
9 brown trout, 4 rainbow trout, and 67 perch were netted on 6 mornings between the 12th and
22nd of January 2015. No salmon were caught. Table 2 present the summary statistics below.
Table 2. Summary statistics of the observed Lake Kaniere Sports fish population January 2015.
Statistic
Length
(mm)
Weight (g)
Weight (lb)
Condition
Factor
Catch rate
(n/100m/hr)
Brown Trout (n=9)
Rainbow Trout (n=4)
Perch (n=67)
Mean
Max
Min
Mean
Max
Min
Mean
Max
Min
422
470
350
459
475
435
248
315
200
856
1.9
1180
2.6
543
1.2
923
0.7
1130
2.5
834
2
235
0.5
493
1.1
111
0.2
1.14
1.33
0.86
0.95
1.97
1.39
1.46
2.08
1.03
0.23
2.42
0
0.11
1.67
0
1.84
11.7
0
Sports fish characteristics of Lake Kaniere in 2006
During the 2006 Lake Kaniere sports fish survey 38 brown trout and 53 Perch were netted on 5
mornings. No rainbow trout or salmon were captured in the survey. Table 3 presents the summary
statistics.
Gillnetting Survey of Lake Kaniere Sports fishery
Page 3 of 6
Table 3. Summary statistics of the observed Lake Kaniere Sports fish population January 2006.
Statistic
Length
(mm)
Weight (g)
Weight (lb)
Condition
Factor
Catch rate
(n/100m/hr)
Brown trout (n=38)
Perch (n=53)
Mean
Max
Min
Mean
Max
Min
474
540
390
266
320
220
1291
2.9
2725
6.1
840
1.9
318
0.7
570
1.3
175
0.4
1.22
2.05
0.75
1.65
1.97
1.39
0.98
4.07
0
1.53
10.53
0
Statistical comparisons of survey data.
Table 3. Statistical comparisons (ANOVA) of brown trout between 2006 and 2015 surveys.
Brown trout
2006
2015
Difference?
Statistic
Means
Means
(P-Value)
Length (mm)
474
422
yes (0.00)
Weight (g)
1291
856
yes (0.00)
Condition
Factor
1.22
1.14
no (0.39)
Catch rate
(n/100m/hr)
0.98
0.23
yes (0.00)
Compared to the 2006 survey, brown trout are smaller and in similar condition. Brown trout catch
rate is lower which indicates that abundance is lower.
Table 4. Statistical comparisons (ANOVA) of perch between 2006 and 2015 surveys.
Perch
Statistic
Length (mm)
Weight (g)
Condition
Factor
Catch rate
(n/100m/hr)
2006
2015
Means
Means
Difference?
(P-Value)
266
318
248
235
yes (0.00)
yes (0.00)
1.65
1.46
yes (0.00)
1.53
1.84
no (0.60)
Compared to the 2006 survey, perch are smaller, and in lower condition. Perch catch rate is similar
which indicates that abundance is similar.
Gillnetting Survey of Lake Kaniere Sports fishery
Page 4 of 6
Diet
The gut sample of 5 brown trout including and two rainbow trout were checked. Where food items
could be identified positively they were noted. Food items present in brown trout guts included;
Bullies, huhu beetles, damsel fly larvae, slender black beetle species, green Beatle, brown beetle and
koura. One rainbow trout had an empty stomach while the other had the following gut content
identified; huhu beetle, damsel fly larvae, slender black beetle species.
The gut sample of 9 perch were checked. Where food items could be identified positively they were
noted. Food items included; Bullies and koura. Six of nine perch had empty stomachs.
From this small sample of sports fish gut content samples it is evident that brown trout, rainbow
trout, and perch compete for food sources.
Discussion
Four rainbow trout were captured during the survey in 2015. Considering the survey methods were
a repeat of the 2006 survey and no rainbows were caught in that survey their presence is a likely to
be the result of enhancement releases that have occurred between 2009 and 2014. The capture of
rainbow trout also confirms that the netting methodology is suitable to capture rainbow trout and
that the methods could be used again in the future to capture rainbow trout. This is the first survey
using this methodology on the West Coast to capture rainbow trout. Therefore, there is no data
available to compare the size, condition and catch rate of rainbow trout with other West Coast lakes.
No salmon were captured in the survey. Two salmon were caught and positively identified by staff as
part of the Take a kid fishing ‘perch comp’ that was held on the lake on the 11th of January 2015.
Therefore it is suggested that the gillnetting survey methodology is not suitable for capturing
salmon. This survey should not be used to assess the success of salmon enhancement releases in
Lake Kaniere.
The number of brown trout caught in the study was low compared to the 2006 survey even though
the 2015 survey had an extra 9 net sets included. This is reflected in catch rate comparisons and
statistically validated that the catch rate in 2015 is lower than 2006. Perch are smaller, have a
smaller condition factor, and are in similar abundance.
Enhancement releases of sports fish have the potential to create an increase in competition for food
sources and spawning grounds with the resident sports fish. This competition may lead to a change
in the population dynamics of sports fish in the lake. Further research would be necessary to
evaluate any changes caused on the sports fish population dynamics of Lake Kaniere from
enhancement.
In light of the spawning limitations and migration barriers in the catchment the continuation of the
enhancement programme will ensure rainbow trout are present in the lake for anglers. Brown trout
enhancement releases are another option to offset recruitment limitations however the availability
of brown trout is not reliable from hatcheries. Brown trout are resident in the lake and surveys
shows they are in good condition.
Gillnetting Survey of Lake Kaniere Sports fishery
Page 5 of 6
Staff recommendations



Continue to enhance Lake Kaniere with rainbow trout.
Continue to enhance Lake Kaniere with brown trout when available.
That the council receives the report.
References
Kelly, D. 2006. Gillnetting Survey of the Lake Kaniere Sports Fishery. Fish & Game Internal Report.
Fish & Game West Coast.
Fish & Game Operational Workplan (2014/2014). Fish & Game Internal Report. Fish & Game West
Coast.
Appendix – Latitude and Longitude references of 2015 Lake Kaniere gillnetting
sites.
Site
001
002
003
004
005
006
007
008
009
010
011
012
013
014
015
016
017
018
Latitude
Longitude
42.812624
42.813482
42.814573
171.1548151
171.1556668
171.1565493
42.820146
42.821024
42.822243
42.837329
42.838836
42.840839
171.1568472
171.1575291
171.1586096
171.1581804
171.1596949
171.1624769
42.849941
42.854066
42.856711
42.862341
42.864686
42.866096
171.1566081
171.1554451
171.1557014
171.1556919
171.1558948
171.1570145
42.869087
42.871159
171.1646185
171.1609241
42.867228
171.152313
Site
019
020
021
022
023
024
025
026
027
028
029
030
031
032
033
034
035
036
Latitude
Longitude
42.80553
42.804658
42.803848
171.1502442
171.1495358
171.1484913
42.799092
42.798949
42.79957
42.802488
42.803239
42.805463
171.1417732
171.1392759
171.1367962
171.1328285
171.1306573
171.1291686
42.812553
42.813658
42.815415
42.820498
42.822111
42.825492
171.1292169
171.1304512
171.1304310
171.1329664
171.1330533
171.1339963
42.83116
42.832868
171.1351902
171.1361718
42.835049
171.1355151
Gillnetting Survey of Lake Kaniere Sports fishery
Page 6 of 6
Site
037
038
039
040
041
042
043
044
045
046
047
048
049
050
051
052
053
054
Latitude
Longitude
42.84238212
42.84523465
42.84685965
171.1341698
171.1345231
171.1329467
42.85165276
42.85352754
42.85549444
42.85907988
42.86061184
42.86321551
171.1354194
171.1363351
171.1372106
171.1387031
171.1391514
171.140759
42.84500054
42.84735552
42.84556817
42.86659308
42.86619720
42.86758164
171.1643346
171.1638126
171.1605013
171.1591094
171.1609818
171.1645382
42.86746153
42.86660373
171.1499482
171.1464131
42.86517520
171.1440456