Selectivity experiments with escape windows in the North Sea Nephrops (Nephrops norvegicus) trawl fishery
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Published source details
Madsen N., Moth-Poulsen T., Holst R. & Wileman D. (1999) Selectivity experiments with escape windows in the North Sea Nephrops (Nephrops norvegicus) trawl fishery. Fisheries Research, 42, 167-181.
Published source details Madsen N., Moth-Poulsen T., Holst R. & Wileman D. (1999) Selectivity experiments with escape windows in the North Sea Nephrops (Nephrops norvegicus) trawl fishery. Fisheries Research, 42, 167-181.
Actions
This study is summarised as evidence for the following.
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Fit mesh escape panels/windows to a trawl net Action Link |
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Fit mesh escape panels/windows to a trawl net
A replicated, paired, controlled study in 1993 of two seabed areas in the North Sea off Scotland, UK (Madsen et al. 1999) found that prawn trawl nets fitted with a square mesh escape panel in the codend caught fewer undersized non-target haddock Melanogrammus aeglefinus and Atlantic cod Gadus morhua, but not whiting Merlangius merlangus, compared to a conventional trawl without a panel. Numbers of undersized haddock (<35 cm) and cod (<40 cm) were lower in codends with an escape panel than conventional codends (haddock, with: 3,207, without: 6,360; cod, with: 650, without: 976), and undersized whiting (<23 cm) catches were similar (with: 16, without: 37). Catches of marketable sizes were similar in panel and conventional codends for haddock (282 vs 284) and cod (464 vs 485) but lower for whiting (1,671 vs 4,074). In addition, catches were similar in panel and conventional codends for undersized (<4 cm) Norway lobster Nephrops norvegicus (4,386 vs 4,940) but lower for legally sized lobster (4,103 vs 1,769). The selection length (the length at which half of fish of that size will escape and half will be retained) was higher in panel than conventional codends for haddock (28.1 vs 25.2 cm) and whiting (35.1 vs 31.4 cm) but similar for cod (29.8 vs 26.3 cm) and lobster (3.8 vs 3.8 cm). Two research cruises were carried out in Fladen Ground and East Ground in 1993 using a twin trawl. One trawl was fitted with a 2 × 1.15 m long square mesh (90 mm) panel 2 m ahead of the codend, and one used a conventional codend. Both codends used 90 mm diamond mesh. Two small mesh covers installed over the codends and square mesh panel collected the escaping catch. Sub-samples of cover and codend catches were sorted and weighed, and lengths recorded.
(Summarised by: Leo Clarke)
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