Reducing flatfish bycatch in roundfish fisheries

Published source details Santos J., Herrmann B., Mieske B., Stepputtis D., Krumme U. & Nilsson H. (2016) Reducing flatfish bycatch in roundfish fisheries. Fisheries Research, 184, 64-73.
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This study is summarised as evidence for the following.

	Action	Category
	Fit rigid (as opposed to mesh) escape panels/windows to a trawl net Action Link

Fit rigid (as opposed to mesh) escape panels/windows to a trawl net

A replicated, paired, controlled study in 2013 of an area of seabed in the western Baltic Sea (Santos et al. 2016) found that a trawl net modified with rigid escape windows in a section of net mounted in front of the codend, reduced the catches of unwanted flatfish compared to a trawl net without rigid escape windows. Total catches of plaice Pleuronectes platessa were 56% lower and flounder Platichthys flesus 62% lower in the modified trawl compared to standard trawl (windows: 1,033–1,310 fish, no windows: 2,354–3,437 fish). There was no significant difference in overall catches of the commercial target species, cod Gadus morhua, in the modified and standard trawls (windows: 1,602 fish, no windows: 1,824 fish) or of undersized cod (windows: 255 fish, no windows: 377). Catch comparison trials were done in March 2013 on a commercial twin trawler on cod fishing grounds west of the island of Bornholm. A total of 12 paired trawl deployments were completed using one modified trawl and one standard trawl net. Both nets were identical and fitted with a mandatory design of selective codend of large square mesh (“Bacoma”). In the modified trawl, rigid grid-like escape windows of 38 mm horizontal bar spacing were incorporated in the two side panels of a four-panel net extension piece in front of the codend (“FRESWIND” system - see paper for specifications). Catches from each haul were weighed by species, and the total length of all fish measured.

(Summarised by: Natasha Taylor)