Catch comparison of flatfish pulse trawls and a tickler chain beam trawl

Published source details Van Marlen B., Wiegerinck J.A.M., van Os-Koomen E. & van Barneveld E. (2014) Catch comparison of flatfish pulse trawls and a tickler chain beam trawl. Fisheries Research, 151, 57-69.
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This study is summarised as evidence for the following.

	Action	Category
	Use a pulse trawl instead of a beam trawl Action Link
	Use an electric (pulse) trawl Action Link

Use a pulse trawl instead of a beam trawl

A replicated, controlled study in 2011 in sandy areas in the North Sea, Netherlands (Van Marlen et al. 2014) found that pulse trawls caught fewer unwanted invertebrates compared to traditional beam trawls, but the effects varied with species. Fewer unwanted invertebrates were caught when using pulse trawls compared to using beam trawls (pulse: 142 vs beam: 177 individuals/ha). However, when sorted by groups, pulse trawls caught fewer invertebrates living on the sediments (131 vs 175) but more living inside the sediment (11 vs 2), compared to beam trawls. In particular, pulse trawls caught fewer echinoderms (82 vs 113) and gastropods (sea snails; 0.0 vs 0.1), compared to the beam trawl, similar numbers of anthozoan (0.0 vs 0.1), bivalves (0.1 vs 0.2), cephalopods (0.1 vs 0.2), and crustaceans (60 vs 64). Pulse trawls also caught 57% less total discards (non-commercial unwanted catch of invertebrates and fish) by volume (0.25 vs 0.29 basket/ha). The pulse trawl reduced the volume of commercial catch by 19% compared to the traditional trawl (0.08 vs 0.1 basket/ha). Pulse (electrical) trawling was prohibited in European fisheries in 1998, but a system of derogations set up in 2006 has allowed the practice to continue, including experimental trials. Comparison trials were conducted in May 2011 with three vessels fishing side-by-side (two boats using pulse trawls, one using traditional flat-fish tickler chain beam trawls). Catches from 33 trawls/vessel were assessed. The total discard volume was measured. Invertebrate discards were identified and counted from one subsample of total catch/trawl (35 kg basket). As of 2019, the practice has been fully banned in European waters.

(Summarised by: Anaëlle Lemasson & Laura Pettit)
Use an electric (pulse) trawl

A replicated, paired, controlled study in 2011 in an area of seabed in the North Sea, Netherlands (van Marlen et al. 2014) found that fishing for flatfish using an electric pulse trawl reduced the catches of discarded fish and undersized plaice Pleuronectes platessa and sole Solea solea compared to a conventional beam trawl. Average catch rate of all discarded fish (mainly bottom dwelling species – see paper for data for individual species/groups) was reduced by 57% in the pulse trawl (108 fish/ha) compared to the beam trawl (62 fish/ha). Fewer individuals of smaller sizes of the target species plaice and sole were caught in the pulse trawl than the beam trawl (data reported graphically). Data were collected in May 2011 from 126 trawl by three vessels fishing near each other. Two vessels used different types of pulse equipment (data pooled) and the other was a conventional tickler chain beam trawl (see original paper for specifications). Discarded catch was sampled from 33 hauls from each vessel.

(Summarised by: Chris Barrett)