Abstract

AbstractAlthough fishing with electricity is illegal in the European Union, a number of temporary licences allowed converting beam trawlers to pulse trawling. To analyse how the adaption of pulse trawling changed this fishery, we studied fishing speeds and landings per unit effort as proxies for catch efficiencies for the main target species. Compared to conventional tickler chain beam trawls, pulse trawls were towed at lower speeds (small vessels −10%, large vessels −23%). Large vessels that switched from conventional beam trawls to pulse trawls at the end of 2009 gradually increased catch efficiency for sole over the period of almost 1 year. While pulse trawling was found to have higher catch rates (kg/h) for sole (small vessels +74%, large vessels +17%), lower catch rates were observed for plaice (small vessels −31%, large vessels −32%). Vessels that switched later achieved immediate gains in catch efficiency for sole. The change in catch efficiency is likely due to the difference in cramp response between the species.

Highlights

  • Fisheries are characterized by a continuous development to improve their efficiency (Valdemarsen, 2001; Ward and Hindmarsh, 2007; Eigaard et al, 2014)

  • The classification of trips resulted in 26 913 trips that were classified for the large beam trawlers, and 9653 trips that were classified for the small trawlers

  • 15 889 trips were classified as traditional trawling, while 10 944 trips were classified as pulse trawling

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Summary

Introduction

Fisheries are characterized by a continuous development to improve their efficiency (Valdemarsen, 2001; Ward and Hindmarsh, 2007; Eigaard et al, 2014). The average rate of efficiency increases due to the cumulative effect of improvements (technology creep) is estimated at 3% (Eigaard et al, 2014). Efficiency can show a sudden jump that is related to major technological innovations. Examples of such radical changes are the introduction of steam propulsion that allowed bottom trawlers to switch from using a small mouthed beam trawl to a wide mouthed otter trawl, substantially increasing catch efficiency (Engelhard, 2008; Kerby et al, 2012; Thurstan et al, 2014). The use of fish finders in combination with the introduction of synthetic fibres and VC International Council for the Exploration of the Sea 2020.

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