Presentation is loading. Please wait.

Presentation is loading. Please wait.

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,

Similar presentations


Presentation on theme: "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,"— Presentation transcript:

1 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

2 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 Structure of presentation

3 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

4

5 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)

6 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

7 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

8 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

9 Hydroacoustics in Loweswater 4 June 2007 and 24 June 2008 Day Very few fish

10 Hydroacoustics in Loweswater 4 June 2007 and 24 June 2008 Night Very few fish

11 4 June 2007 and 24 June 2008 Day Very few fish Night Very few fish Hydroacoustics in Loweswater

12 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

13 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? Hydroacoustics in Loweswater

14 4 June 2007 and 24 June 2008 Chaoborus (phantom midge larvae) Extremely abundant and unexpected 1 cm Hydroacoustics in Loweswater

15 6 protons 6 neutrons 6 protons 7 neutrons protons electrons neutrons Carbon-12Carbon-13 Stable Isotopes Analysis Redrawn from graphic kindly provided by Chris Harrod of Queens University, Belfast

16 δ 13 C = -27 δ 15 N = 2 δ 13 C = -35 δ 15 N = 2 δ 13 C = -34 δ 15 N = 6 δ 13 C = -18 δ 15 N = 2 Stable Isotopes Analysis Redrawn from graphic kindly provided by Chris Harrod of Queens University, Belfast

17 Stable Isotopes Analysis Redrawn from graphic kindly provided by Chris Harrod of Queens University, Belfast

18 Stable Isotopes Analysis in Loweswater ? Redrawn from graphic kindly provided by Chris Harrod of Queens University, Belfast

19 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

20 Dub Beck Environment Agency stream surveys

21 Mosedale Beck Environment Agency stream surveys

22 Park Beck Environment Agency stream surveys

23 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)

24 National Trust fishing returns Loweswater Crummock Water

25 National Trust fishing returns Loweswater Crummock Water

26 National Trust fishing returns Loweswater Crummock Water

27 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

28 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

29 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


Download ppt "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,"

Similar presentations


Ads by Google