The effective selectivity of a composite gear for industrial fishing: a sorting grid in combination with a square mesh window
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Published source details
Eigaard O.R. & Holst R. (2004) The effective selectivity of a composite gear for industrial fishing: a sorting grid in combination with a square mesh window. Fisheries Research, 68, 99-112.
Published source details Eigaard O.R. & Holst R. (2004) The effective selectivity of a composite gear for industrial fishing: a sorting grid in combination with a square mesh window. Fisheries Research, 68, 99-112.
Actions
This study is summarised as evidence for the following.
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Fit a size-sorting escape grid (rigid or flexible) to a fish trawl net Action Link |
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Fit a size-sorting escape grid (rigid or flexible) to a fish trawl net
A replicated study in 2000 of a pelagic area of the North Sea, Scotland (Eigaard & Holst 2004) reported that a fish trawl fitted with a size-sorting escape grid system reduced the catch of non-target whiting Merlangius merlangus and haddock Melanogrammus aeglefinus in an industrial fishery targeting the smaller-sized species Norway pout Trisopterus esmarki, relative to the overall catch. Data were not tested for statistical significance. Catches of whiting and haddock were reduced in weight by 57% and 37% respectively by the grid. Almost all whiting sorted out were above the minimum landing size (23 cm), whereas for haddock the main sizes of the fish sorted out were below the 32 cm minimum landing size (data reported as length frequency distributions). Relative to retained catch, losses of fish above the minimum landing size were estimated as 46% for whiting and 9% for haddock. Catches of the target species Norway pout were reported to be reduced by 7%. Data were collected in November/December 2000 from 27 valid trawl deployments on a major Norway pout fishing area in the northern North Sea. An industrial trawl fitted with a hinged grid of 24 mm bar spacing was inserted in front of the codend. The top of the grid was covered by a square mesh window of 108 mm mesh to retain larger marketable fish (see paper for specifications). Covers attached over the top of the grid and the square mesh window collected escaped fish and fish retained by the window. Sub-samples of fish from the two covers and the codend catch were sorted and weighed and fish lengths measured.
(Summarised by: Natasha Taylor)
Output references
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