Effects of fishing disturbance on benthic communities and secondary production within an intensively fished area

Demersal fishing alters seabed habitats and affects the structure and functioning of ben- thic invertebrate communities. At a critical level of disturbance, such communities may approach an equilibrium disturbed state in which a further increase in disturbance has little additional impact. Such arguments have been used to suggest that an ecosystem approach to fisheries management (EAFM) should protect lightly fished areas and deflect fishing activity into areas that are already intensively fished. In this study, the effects of variation in fishing disturbance on the secondary pro- duction, species diversity, abundance, biomass, and community structure of benthic infauna were examined in a region of the German Bight (North Sea) that has been intensively trawled for decades. Variation in fishing disturbance across the study area was determined using automated position reg- istration and vessel monitoring through satellite. Even in such a heavily fished area, linear regression analyses revealed that biomass, species richness, and production decreased significantly with increasing fishing intensity. Although redundancy analyses (RDA) showed that sediment character- istics were influential in determining the structure of the infauna community, partial RDA revealed that fishing continued to have an impact on community structure in terms of biomass. These results suggest that, in implementing an EAFM, managers will need to consider the possibility that, even in areas with high chronic fishing disturbance, further increases in fishing activity may still cause addi- tional damage to benthic invertebrate communities.