Title: Gillnet selectivity of Salmo trutta L. from two lakes in Iceland as a reference for practical application on Lake Kainji fisheries

Final project
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Supervisors: Haraldur Einarsson


This study demonstrates the selectivity pattern of brown trout (Salmo trutta) from ten gillnets forming series of mesh sizes 12, 16.5, 18.5, 21.5, 25, 30, 35, 40, 50 and 60 mm (half mesh). Data collected between 1994 and 2014 from Lakes Hraunsfjarðarvatn and Baulárvallavatn in Iceland was used for this study. The ratios of fish lengths to the mesh sizes were used on the selection model. Five types of models were fitted to the data from the mesh sizes: normal location, normal spread, lognormal, bi-normal, and bi-lognormal. The bi-normal model gave the best fit of the data with the lowest deviance (601.339). The study showed fish length increase with increased mesh size but a decrease in number of catch. Majority of the fish in these lakes are immature, size groups 13-37 cm caught in mesh sizes 33 mm and 43mm. Mesh sizes could be added to the net series to ensure coverage of more class sizes. This type of study can serve as a basis for recommending the mesh sizes of gillnet that best suits the fish stock, hence better management of the fishery.

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