Seal related projects

Transcription

1 Seal related projects at the Swedish University of Agricultural Sciences (SLU) Diet 2. Seal safe fishing gear HELCOM SEAL Swedish University of Agricultural Sciences karl.lundstrom@slu.se

2 ECOSEAL Central Baltic Interreg project ; ICES SD 27, 29, 30, 32 Finnish Game and Fisheries Research Institute Swedish University ofagriculturalsciences (SLU) University of Helsinki Fisheries and Environmental Management Group Department of Biosciences University of Tartu Swedish Museum of Natural History University of Jyväskylä University of Oulu

3 ECOSEAL WP4: The ecological role of Baltic grey seals Dietary patterns Digestive tracts (visible prey remains + DNA) Fatty acids (blubber) Stableisotopes (liver er+ muscle) Synthesis and comparison Diet compositions obtained dfrom different dff tissues and estimation methods Prey consumption/requirements i Bioenergetic modelling Grey seals: n=217 Fish: n=450

4 ECOSEAL DNA vs. hard parts from digestive tracts (n=155) Occurrence (%) Prey Hard parts DNA Prey Hard parts DNA Herring 46% 62% Flounder 3% 5% Perch 23% 28% Eel 2% 4% Cyprinids 21% 32% Whitefish+vendace 9% 17% Eelpout 17% 25% Salmon+trout 2% 5% Smelt 12% 14% Stickleback 1% 8% Sprat 8% 24% Pike 1% 1% Pike perch 5% 17% Cod 4% 8% Ammodytidae 3% 3%

5 Compilation of grey seal diet data Sweden + Finland Hunt + bycatch n > 1,000 Collaboration with SMNH and FGFRI

6 t proport tion Weigh 0,90 0,80 0,70 Compilation of grey seal diet data ,60 0,50 Sweden + Finland 0,40 Hunt + bycatch 0,30 0, ,10 n > 1,000 Hunted greyseals Collaboration with SMNH and FGFRI 0,00 rbot Bu Cod Eelp pout Her rring Pike Sm melt Sprat Vend dace White efish idae Ammodyt idae Perc ICES SD27 (n=59) ICES SD29 (n=92) ICES SD30 (n=223) ICES SD31 (n=218) ICES SD32 (n=32) Salmo spp idae euronect Pl idae Gobi idae Cott idae Cyprin idae Unknown n_salmon

7 Ringed seal diet in the Bothnian Bay Ringed Vikaresäl, seals, Bothnian Bottenviken, Bay, (n=43) 0,5 0,4 03 0,3 0,2 0,1 Weight Viktandel proportion 0 Other speciess Övriga Nors Smelt Fourhorned sculpin Hornsimpa Tånglake Eelpout Storspigg Sticklebacks Siklöja Vendacee Strömming Herring SLU AQUA Reports 2014:1

8 Ringed seal diet in the Bothnian Bay Combine with Finnish data (n=37) FGFRI, Univ. Jyväskylä, Univ. Helsinki Fatty acid composition Blubber samples Stable isotopes Tissue samples (muscle, liver) Prey DNA Digestive tract contents

9 Competition for the fish Stockholm University Quantification of fish removal in the Baltic Sea Marine mammals Birds Fisheries Collaboration with SMNH, DTU Aqua, Åbo Akademi University, Uppsala University

10 Small scale local studies Conditions for continuous monitoring of diet Baltic grey seals Faecal scats Traditional hard part analysis DNA analysis

11 Grey seals in the southern Baltic Sea Lack of dietary data No hunt Very few reported/collected bycatches Faecal scats Traditional hard part analysis DNA analysis Grey seals and harbour seals Collaboration with Denmark

12 Gear development e e Seal safe fishing gear Reduce bycatches Mammals Birds Fish Seals and fisheries Sara Königson & Sven Gunnar Lunneryd Alternatives to gill netfisheries

13 Seal fisheries interactions are increasing with increasing seal populations n vessels; % without seal dama ge Number of fishing vessels % of fishing efforts without seal damage Catch (kg/day)

14 Cod pots A possible solution?

15 Cod pots A possible solution?

16 Catch differences between areas Might not work everywhere ± 95% Confidence interval 2,5 2 kg cod per pot 1,5 1 0, Area

17 Submerged pontoon trap for cod (6 12 m depth) First test 2014 Still much to work with

18 Danish seine with smaller boats in coastal waters Promising result during pilot tests 2014: flounder, perch, vendace and herring.

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