A first look at the fish community of Loweswater

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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

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Structure of presentation

• Acknowledgements
• CEH lake survey (2007 and partially repeated in
  2008)
• CEH Stable Isotope Analysis with Queens
  University, Belfast
• Environment Agency stream surveys (1991 to 2006)
• National Trust fishing returns (1989 to 1996)
• A partial history of local fisheries management
• Summary

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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 Queens University, Belfast

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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)
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Netting findings
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
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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
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Hydroacoustics
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
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Hydroacoustics in Loweswater
4 June 2007 and 24 June 2008 Day Very few
fish
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Hydroacoustics in Loweswater
4 June 2007 and 24 June 2008 Night Very few
fish
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Hydroacoustics in Loweswater
4 June 2007 and 24 June 2008 Day Very few
fish Night Very few fish
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Fish abundance and phosphorus concentrations
Loweswater
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.
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Hydroacoustics in 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?
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Hydroacoustics in Loweswater
4 June 2007 and 24 June 2008 Chaoborus
(phantom midge larvae) Extremely abundant and
unexpected
1 cm
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Stable Isotopes Analysis
Carbon-12
Carbon-13
electrons
neutrons
protons
6 protons 6 neutrons
6 protons 7 neutrons
Redrawn from graphic kindly provided by Chris
Harrod of Queens University, Belfast
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Stable Isotopes Analysis
d13C -27 d15N 2
d13C -35 d15N 2
d13C -34 d15N 6
d13C -18 d15N 2
Redrawn from graphic kindly provided by Chris
Harrod of Queens University, Belfast
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Stable Isotopes Analysis
Redrawn from graphic kindly provided by Chris
Harrod of Queens University, Belfast
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Stable Isotopes Analysis in Loweswater
?
Redrawn from graphic kindly provided by Chris
Harrod of Queens University, Belfast
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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
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Environment Agency stream surveys
Dub Beck
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Environment Agency stream surveys
Mosedale Beck
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Environment Agency stream surveys
Park Beck
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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)

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National Trust fishing returns
Loweswater
Crummock Water
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National Trust fishing returns
Loweswater
Crummock Water
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National Trust fishing returns
Loweswater
Crummock Water
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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

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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

Loweswater
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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 lakes
  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