Selectivity experiments to estimate the effect of escape windows in the Skagerak roundfish fishery

Published source details Madsen N. & Stæhr K. (2005) Selectivity experiments to estimate the effect of escape windows in the Skagerak roundfish fishery. Fisheries Research, 71, 241-245.
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This study is summarised as evidence for the following.

	Action	Category
	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 2000 of a bottom fishing ground in the Skagerrak, northern Europe (Madsen & Staehr 2005) found that fitting square mesh escape windows to bottom trawl codends improved the size selectivity of small Atlantic cod Gadus morhua in two of two cases and of haddock Melanogrammus aeglefinus in one of two cases, compared to a standard codend without escape windows. For cod, the selection length (the length at which fish have a 50% chance of escape) was greater in both top- and side-window codends than no windows (top: 29.9 cm, side: 29.9 cm, none: 25.5 cm) and for haddock, the selection length was higher only in the top-window codend (top: 31.9 cm, side: 28.8 cm, none: 28.8 cm). Trials were done in June 2000 on a commercial fishing vessel towing a twin-trawl net. Data were collected from 37 deployments of a small-meshed (35 mm) control codend fished at one side and a test codend at the other side, and sides changed regularly. Three codend types were tested: a standard codend (104 mm mesh) with an 85 mm square mesh top window; a standard codend with two 85 mm square mesh side windows; and a standard codend (see paper for specifications). Deployments were 2.9 h duration, speed 3.1 knots and 20–80 m depths. Fish sampling procedure was not reported.

(Summarised by: Natasha Taylor)