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A first look at the fish community of Loweswater
Ian J Winfield, Janice M Fletcher, J Ben James & Stephen J Thackeray
Centre for Ecology & Hydrology, Lancaster, UK
• Acknowledgements• CEH lake survey (2007 and partially repeated in 2008)• CEH Stable Isotope Analysis with Queen’s University, Belfast• Environment Agency stream surveys (1991 to 2006)• National Trust fishing returns (1989 to 1996)• A partial history of local fisheries management• Summary
Structure of presentation
Acknowledgements
• Numerous colleagues within the Lake Ecosystem Group of CEH
• Mark Astley and Katherine Hearne of the National Trust
• Andy Gowans and Keith Kendall of the Environment Agency
• Chris Harrod of Queen’s University, Belfast
Lake survey
4 to 6 June 2007
Hydroacoustics (12 transects: day and night)
Survey gill nets (3 sets: inshore, offshore surface and offshore bottom)
Fyke nets (10 sets: inshore)
Total
0
20
40
60
80
100
Brown trout Perch
Species
Per
cen
tag
e
Offshore surface
0
20
40
60
80
100
Brown trout Perch
Species
Per
cen
tag
e
Inshore
0
20
40
60
80
100
Brown trout Perch
Species
Per
cen
tag
e
Offshore bottom
0
20
40
60
80
100
Brown trout Perch
Species
Per
cen
tag
e
Survey gill nets (inshore: 71 perch (79 to 367 mm); offshore surface: 3 brown trout; offshore bottom: no fish)
Fyke nets (inshore: 1 minnow, 10 perch)
[Pike also known to be present]
Netting findings
Perch length-weight relationship Indicates good individual condition
Perch length frequency distribution Diverse and includes large individuals
Perch growth curve Indicates high growth rate and ultimate size
Netting findings
0
2
4
6
8
10
12
0 30 60 90 120
150
180
210
240
270
300
330
360
390
Length class (mm)
Per
cen
tag
e
0
50
100
150
200
250
300
350
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Age class (years)
Mea
n l
eng
th (
mm
)
0
100
200
300
400
500
600
700
800
900
0 50 100 150 200 250 300 350 400
Length (mm)
Wei
gh
t (g
)
Visualise as a cross-section of the lake
Day Typically few fish, often near the lake bottom or edges
Night Typically many more fish, often dispersed throughout the water column. Each fish is ‘visible’ as an arch composed of a number of echoes
Quantification to number of fish per hectare by computer analysis
Day
Night
Example echograms from Loch Skeen
Hydroacoustics
Hydroacoustics in Loweswater
4 June 2007 and 24 June 2008
Day Very few fish
Hydroacoustics in Loweswater
4 June 2007 and 24 June 2008
Night Very few fish
4 June 2007 and 24 June 2008
Day Very few fish
Night Very few fish
0
5
10
15
20
25
30
35
40
45
50
Small Medium Large
Length class
Ab
un
dan
ce (
fish
ha
-1)
Hydroacoustics in Loweswater
r2 = 0.4144, n = 16, p < 0.0010.5
1.0
1.5
2.0
2.5
3.0
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4
Log (Winter TP)
Lo
g (
Ab
un
dan
ce (
Fis
h h
a-1))
Fish abundance and phosphorus concentrations
Winfield, I. J., Fletcher, J. M., James, J. B., Bean, C. W. & Duigan, C. (in press). Setting reference values for lake fish abundance: observations from unexploited or lightly exploited vendace (Coregonus albula), whitefish (C. lavaretus) and Arctic charr (Salvelinus alpinus) populations in the U.K. In: Cowx, I. G. (editor) Assessing the Ecological Status of Rivers, Lakes and Transitional Waters. Fishing News Books, Blackwell Scientific Publications, Oxford.
Loweswater
4 June 2007 and 24 June 2008
Day Very few fish
Night Very few fish
Perch apparently do not venture out into the open water at day or night
Identity of the small echoes?
0
5
10
15
20
25
30
35
40
45
50
Small Medium Large
Length class
Ab
un
dan
ce (
fish
ha
-1)
Hydroacoustics in Loweswater
4 June 2007 and 24 June 2008
Chaoborus (phantom midge larvae) Extremely abundant and unexpected
1 cm
Hydroacoustics in Loweswater
6 protons6 neutrons
6 protons7 neutrons
protons
electrons
neutrons
Carbon-12 Carbon-13
Stable Isotopes Analysis
Redrawn from graphic kindly provided by Chris Harrod of Queen’s University, Belfast
δ13C = -27 ‰δ15N = 2 ‰
δ13C = -35 ‰δ15N = 2 ‰
δ13C = -34 ‰δ15N = 6 ‰
δ13C = -18 ‰δ15N = 2 ‰
Stable Isotopes Analysis
Redrawn from graphic kindly provided by Chris Harrod of Queen’s University, Belfast
Stable Isotopes Analysis
Redrawn from graphic kindly provided by Chris Harrod of Queen’s University, Belfast
-30 -25 -20 -15D13CDF
7
8
9
10
11
12
13
14
15
D15
N
ZoopPerchMayflyCladoceraChironomidChaoborus
TAXA
D a p h n ia + 1 T L
D a p h n ia + 2 T L
Stable Isotopes Analysis in Loweswater
?
Redrawn from graphic kindly provided by Chris Harrod of Queen’s University, Belfast
Environment Agency stream surveys
Electrofishing at 16 sites
5 sites sampled once (1991)
8 sites sampled twice (1993 and 1996)
2 sites (Dub Beck and Mosedale Beck) sampled 3 times (1993, 1994 and 1996)
1 site (Park Beck) sampled 4 times (1993, 1994, 1996 and 2006
Trout fry
0.00
0.20
0.40
0.60
0.80
1.00
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
n 1
00 m
-2)
F, F, FTrout parr
0.00
2.00
4.00
6.00
8.00
10.00
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
ind
ivid
ual
s
100m
-2)
C, D, C
Salmon fry
0.00
0.20
0.40
0.60
0.80
1.00
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
n 1
00 m
-2)
F, F, FSalmon parr
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
n 1
00 m
-2)
E, D, E
Dub Beck
Environment Agency stream surveys
Mosedale Beck
Environment Agency stream surveys
Trout fry
0.00
0.20
0.40
0.60
0.80
1.00
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
n 1
00 m
-2)
F, F, FTrout parr
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
ind
ivid
ual
s
100m
-2)
D, D, F
Salmon fry
0.00
0.20
0.40
0.60
0.80
1.00
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
n 1
00 m
-2)
F, F, FSalmon parr
0.00
0.20
0.40
0.60
0.80
1.00
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
n 1
00 m
-2)
F, F, F
Park Beck
Environment Agency stream surveys
Trout fry
0.002.004.006.008.00
10.0012.0014.0016.00
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
n 1
00 m
-2)
E, F, C, CTrout parr
0.000.501.001.502.002.503.003.504.00
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
ind
ivid
ual
s
100m
-2)
D, E, D, E
Salmon fry
0.00
20.00
40.00
60.00
80.00
100.00
120.00
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
n 1
00 m
-2)
F, E, E, ASalmon parr
0.00
5.00
10.00
15.00
20.00
1992 1994 1996 1998 2000 2002 2004 2006
Year
Ab
un
dan
ce (
n 1
00 m
-2)
D, E, E, B
National Trust fishing returns
• Provided by Environment Agency
• Loweswater
– Brown trout
– Pike
– Perch
• Crummock Water
– Brown trout
– Arctic charr
– Pike
– Perch
• 1989 to 1999 (although all returns for 1997 to 1999 were zero)
National Trust fishing returnsTrout
0
50
100
150
200
1989 1990 1991 1992 1993 1994 1995 1996
Year
Cat
ch (
ind
ivid
ual
s)
Trout
0
50
100
150
200
250
300
1989 1990 1991 1992 1993 1994 1995 1996
Year
Cat
ch (
ind
ivid
ual
s)
Loweswater
Crummock Water
Perch
0
200
400
600
800
1000
1989 1990 1991 1992 1993 1994 1995 1996
Year
Cat
ch (
ind
ivid
ual
s)
Perch
0
50
100
150
200
250
1989 1990 1991 1992 1993 1994 1995 1996
Year
Cat
ch (
ind
ivid
ual
s)
National Trust fishing returns
Loweswater
Crummock Water
Pike
0
1
2
3
4
5
6
1989 1990 1991 1992 1993 1994 1995 1996
Year
Cat
ch (
ind
ivid
ual
s)
Pike
0
5
10
15
20
25
30
35
1989 1990 1991 1992 1993 1994 1995 1996
Year
Cat
ch (
ind
ivid
ual
s)
National Trust fishing returns
Loweswater
Crummock Water
A partial history of local fisheries management
• Derived from an article ‘The rise of trout in Loweswater Lake’ published in The Field by Geoffrey Howard White (Date unknown)
• Loweswater bought by the National Trust in 1937
• First-class trout lake from 1937 to 1957, but trout scarce by 1960
• ‘There is plenty of bottom feed in the lake’
• Perch netted and canned during World War II, then increased
• Decision to restore trout fishery taken in 1973 by William Armstrong, National Trust Forester
• Perch traps throughout May for 3 years, removing 7,000 to 8,000 perch daily
• The next stage was ‘to deal with the pike’
• Gill nets set for pike throughout May for 11 years, removing 30 to 40 pike each year
A partial history of local fisheries management
• In 1978, following the drastic reduction in perch and pike, the National Trust stocked with thousands of 6 inch trout
• ‘No real result was shown’
• In 1982, the National Trust stocked with 10 to 12 inch trout
• In 1984, very good catches were made
• In mid 1980s (?) ‘Loweswater Lake has now been restored beyond its former glory into a first-class trout lake’
Trout
0
50
100
150
200
1989 1990 1991 1992 1993 1994 1995 1996
Year
Cat
ch (
ind
ivid
ual
s)
Loweswater
Summary
• Lake fish community presently dominated by inshore perch in good condition
• Few fish in the open water
• Chaoborus extremely abundant in the open water
• Chaoborus may occupy a key role in the food chain, predating on zooplankton which predate on algae
• No current information on fish in the lake’s tributaries
• Post-1990 decline in trout fishery was not shared by nearby Crummock Water
• History of fisheries management by stocking and removal is not recommended for the future
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