Discarding of plaice (Pleuronectes platessa) in the Danish North Sea trawl fishery

Abstract

Plaice (Pleuronectes platessa) plays an important role in the North Sea benthic ecosystem and is by weight the most important commercial flatfish species in the North Sea demersal fishery. There is a high discarding of plaice in the active demersal fisheries in the North Sea. The change in fisheries management towards a more ecosystem based approach, together with a greater focus on sustainability, has caused a severe need for action. Subsequently, the European Commission is preparing regulations to reduce or even ban discards. The trawl fisheries are commercially the most important Danish fishery targeting plaice. Here we analyse discard data collected onboard Danish vessels in the period from 1998 to 2008. We describe the general patterns in these data by dividing them into three mesh size categories: 80–99mm, 100–119mm and ≥120mm to reflect implemented technical measures of relevance. We analyse the landed and discarded portions in these mesh size categories and link the discarding to the minimum landing size. We employed a GAM model to assess how discarding of plaice below the minimum landing size is connected to relevant factors that could be of relevance from a management perspective. We identified a statistical significant effect of mesh size category and area. We discuss the results in relation to potential mitigation measures to be implemented in future fisheries management strategies.