Escape windows to improve the size selectivity in the Baltic cod trawl fishery

Published source details Madsen N., Holst R. & Foldager L. (2002) Escape windows to improve the size selectivity in the Baltic cod trawl fishery. Fisheries Research, 57, 223-235.
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This study is summarised as evidence for the following.

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	Fit mesh escape panels/windows to a trawl net Action Link

Fit mesh escape panels/windows to a trawl net

A replicated, paired, controlled study in 1998 of a seabed area in the Baltic Sea, Denmark (Madsen et al. 2002) found that trawl nets fitted with a square mesh escape window in the codend reduced catches of small unwanted cod Gadus morhua and improved size selectivity, compared to standard diamond mesh codends without a square mesh window. Average weights of cod escaped from codends with square mesh windows was higher than those without (with: 416–613 kg, without: 223-456 kg) and the selection lengths (the length at which half of fish of that size will escape and half will be retained) increased for all three window mesh sizes compared to standard codends of comparable mesh size without a panel (with: 41–53 cm, without: 28–46 cm) and increased with increasing mesh size. In June and July 1998, a total of 54 valid fishing deployments were done from a commercial trawler towing a twin trawl rig around the Danish island of Bornholm. Three modified standard codends, with 110, 125 and 135 mm square mesh escape windows, and three standard codends of 105, 120 and 140 mm diamond mesh size, were tested. The escape window was a single panel of square mesh, 3.5 m long and 1.4 m wide, inserted in the upper panel of the codend section. Covers were attached over each codend to collect escaping fish. Codend and cover catches were sorted and weighed by species. Sub-samples of cod were measured for length.

(Summarised by: Natasha Taylor)