Effort allocation of the Dutch beam trawl fleet in response to a temporarily closed area in the North Sea

The spawning stock of North Sea cod is at a historic low level and immediate management measures are needed to improve this situation. As a first step, the European Commission in 2001 closed a large area in the North Sea between February 15 and April 30 to all cod related fishing fleets in order to protect the spawning population. The closed area comprised important fishing grounds of the beam trawl fleet fishing for flatfish. In this paper the response of the Dutch fleet (components 225-300hp and >300hp) is analysed using data from EU-logbooks and from position recordings from the Vessel Monitoring System. No change was observed in the fleet of small beam trawlers. The fleet of large vessels displaced its activity to fishing grounds in the North Sea outside the closed areas, and to fishing grounds outside the North Sea. In the North Sea, beam trawling concentrated along the borders of closed areas and the Plaice Box. In the first week after the closure the number of trips in the open area doubled. Coinciding with this increase, the catch rate, expressed as revenue per hp-day, decreased. After the area was re-opened, the catch rate was exceptionally high but decreased to the normal level in the 2nd - 3rd week. The change in catch rate in relation to the change in fishing effort indicated that competitive interactions (in particular interference interactions) occurred among vessels. The implication of the observed fleet response is discussed against the background of the objective of the management measure to protect cod and the broader objective of the Common Fisheries Policy of ecosystem management. It is concluded that it is unlikely that cod has benefited from the area closure. Furthermore, the closure may have had a negative impact on the rate of discarding of demersal species and a negative impact on vulnerable components of the ecosystem (e.g. skates, long lived benthic species) due to an increase in trawling activities in certain areas

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