ICES - Report of the Workshop to Assess the Ecosystem Effects of Electric Pulse Trawls (WKPULSE)
Following the ICES Advice on Pulse Trawling on flatfish of 2006 further studies were carried out by IMARES, the Netherlands on catsharks (Scyliorhinus canicula L.), cod (Gadus morhua L.) and a range of benthic species (ragworm (Nereis virens L.), common prawn (Palaemon serratus L.), subtruncate surf clam (Spisula subtruncata L.), European green crab (Carcinus maenas L.), common starfish (Asterias rubens L.), and Atlantic razor clam (Ensis directus L.) under pulse stimulation of the Verburg-Holland system. These studies were reviewed and discussed at the meeting of the Workshop to Assess the Ecosystem Effects of Electric Pulse Trawls (WKPULSE).
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The reviewing experts concluded that there is primarily more information needed on the effect on cod be-fore the pulse trawl can be allowed on a commercial basis. The reviewing experts could not be convinced that the simulator provided an adequate representation of the in situ pulse, due to the fact that they were not able to review the specifications of the pulse characteristics resulting from confidentiality issues. They recommended that a three-dimensional temporal-spatial model of exposure of cod inside the trawl using information about behavioural responses validated by direct underwater observation would be useful. Furthermore it was suggested to investigate the effect of pulses on the electro-receptor organs of elasmobranchs, and determine the catch rates of these fish in beam trawls. Also to look at other gadoid species: e.g. haddock, and whiting. It was also suggested to investigate the effect of the pulse on the reproductive capabili-ties of benthos, but weigh this against the mortality in the conventional tickler chain beam trawl. In addition concerning enforceability and control it was noted that there are indications that the limits used in the present derogation that are deemed needed for fraud-resistant control (electrical power limited to 2.5 kW/m beam length, and amplitude to maximum 15 V) will not be sufficient to ensure that fishing efficiency with pulse trawls will not be raised in future, and it is recommended to investigate this aspect further and suggest limits that can. A presentation was also given about the development of a pulse trawl for the brown shrimp (Crangon crangon L.) fishery in Belgium. When both flatfish and shrimp trawling are considered pulse trawling will be an important issue for hundreds of fishing vessels in countries around the North Sea and the suggestion to set up an ICES Study Group on electrical fishing was mooted.