A simple technical measure to reduce bycatch and discard of skates and sharks in mixed-species bottom-trawl fisheries

Published source details Kynoch R.J., Fryer R.J. & Neat F.C. (2015) A simple technical measure to reduce bycatch and discard of skates and sharks in mixed-species bottom-trawl fisheries. ICES Journal of Marine Science, 72, 1861-1868.
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This study is summarised as evidence for the following.

	Action	Category
	Modify design or arrangement of tickler chains/chain mats in a bottom trawl Action Link

Modify design or arrangement of tickler chains/chain mats in a bottom trawl

A replicated, paired, controlled study in 2005 in an area of seabed in deep water in the Atlantic Ocean off the Isle of Skye, Scotland, UK (Kynoch et al. 2015) found that removal of the tickler chain from a bottom trawl reduced the capture of unwanted skates/rays (Batoidea) and unwanted sharks (Chondrichthyes) compared to a standard trawl with a tickler chain. Overall, trawl gear without a tickler chain decreased the catch of skates/rays (four species) and sharks (three species) compared to a trawl with a tickler chain (skates/rays, without: 198 individuals, with: 625 individuals; sharks, without: 993 individuals, with: 1,357 individuals). For the more commercially valuable species, overall catch rates of three flatfish species (Pleuronectidae) and two cod-like species (Gadidae) were similar between trawls, however, catch rates of two anglerfish Lophius sp. decreased with a tickler chain (see paper for data). Trials took place onboard a commercial fishing vessel in October 2005. A total of 17 paired deployments of standard bottom fish trawls, one with the tickler chain removed, were made, parallel to one another, at 120–170 m depth.

(Summarised by: Chris Barrett)