A study of optimum positioning of square-mesh escape panels in Irish Sea Nephrops trawls

Published source details Armstrong M.J., Briggs R.P. & Rihan D. (1998) A study of optimum positioning of square-mesh escape panels in Irish Sea Nephrops trawls. Fisheries Research, 34, 179-189.
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This study is summarised as evidence for the following.

	Action	Category
	Modify the configuration of a mesh escape panel/window in a trawl net Action Link

Modify the configuration of a mesh escape panel/window in a trawl net

A replicated, paired study in 1994–1995 of two areas of seabed in the Irish Sea, UK and Ireland (Armstrong et al. 1998) found that trawl nets fitted with a square mesh escape panel located 7 m in front of the codend allowed more undersized whiting Merlangius merlangus to escape in one of two cases, compared to trawl nets with a panel 1 m in front of the codend. In twin trawl net deployments, fewer undersized (<27 cm) whiting were caught with the panel 7 m in front of the codend (72 fish/h) than with the panel immediately in front (131 fish/h). However, in parallel net deployments undersized catch was the same (88 fish/h) between trawl designs. Catch of legally sized whiting (>27 cm) was not statistically different between trawl designs in twin trawls (7 m panel: 40, 1 m panel: 50 fish/h) or parallel trawls (7 m panel: 85, 1 m panel: 83 fish/h). In summer of 1994 and 1995, a total of 43 twin and 40 parallel trawl net deployments were undertaken respectively, using two Nephrops norvegicus trawl nets fitted with a 3 m square mesh (75 mm) escape panel for 4–5 h each. In one trawl net, the panel was fitted 1 m ahead of the codend, consistent with UK regulations, and in the other trawl net it was fitted 7 m ahead of the codend, consistent with Irish regulations. Each trawl net was 70 mm diamond mesh. Twin trawl nets were towed by a single vessel and parallel net deployments were done by two vessels towing a single trawl each. Full details of the trawl designs are provided in the original paper. All fish caught were identified and the length recorded.

(Summarised by: Leo Clarke)