Effects of Turtle Excluder Devices on bycatch and discard reduction in the demersal fisheries of Mediterranean Sea

Published source details Sala A., Lucchetti A. & Affronte M. (2011) Effects of Turtle Excluder Devices on bycatch and discard reduction in the demersal fisheries of Mediterranean Sea. Aquatic Living Resources, 24, 183-192
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This study is summarised as evidence for the following.

	Action	Category
	Fit a size-sorting escape grid (rigid or flexible) to a fish trawl net Action Link

Fit a size-sorting escape grid (rigid or flexible) to a fish trawl net

A replicated study in 2008 of three bottom trawling sites in the North Adriatic Sea, Italy (Sala et al. 2011) found that fish trawl nets fitted with size-sorting escape grids (Turtle excluder devices) typically reduced the amounts of discarded fish catch and overall discarded catch (fish and invertebrates combined), relative to the codend catch. For three of three designs, grids reduced the average catch rates of nine of 12 discarded fish species (see paper for list of species) compared to the total catch that would have been retained if no grids were fitted (with: 0.17–1.27 kg/tow, without: 0.34–2.45 kg/tow), and for three of 12 fish species average catch rates were similar (with: 0.58–1.16 kg/tow, without: 0.58–1.50 kg/tow). Average catches of all discarded catch (fish and invertebrates) were reduced in nets with grids (with: 9–21 kg/tow, without: 25–28 kg/tow). Three different grid designs (flexible, rigid and semi-rigid construction), all with bottom escape openings, were tested in standard fish trawls used in Mediterranean bottom fisheries (see paper for specifications). Catch data was collected from 42 fishing deployments (11–15 per grid) in March 2008. Fish and marine invertebrates escaping through the grid were collected in a cover attached over the grid outlet. Cover and codend catches were pooled to calculate total catch of a ‘control’ net without a grid.

(Summarised by: Khatija Alliji)