Natural vs. fishing disturbance: drivers of community composition on traditional king scallop, Pecten maximus, fishing grounds

Scallop dredging is considered to be one of the most damaging forms of fishing to benthic habitats, although these effects vary among different habitats. The present study characterizes the biological communities that occur within the spatial limits of the English Channel king scallop dredge fishery in relation to key environmental drivers [mean seabed temperature; seabed temperature range; interannual temperature variation; bed shear stress (BSS); substrate characteristics; and depth] and across a gradient of scallop dredging intensity derived from vessel monitoring system data. Dredge fishing intensity was not correlated with species richness, species diversity, or species composition. However, increasing tidal BSS had a significant negative correlation with species richness and diversity. This outcome indicates that it is not possible to demonstrate that there is an effect of scallop fishing within the current spatial limits of the king scallop dredge fishery. This may be because historical dredge fishing could have already altered the benthic communities within the area of the scallop fishery to those that are resilient to scallop dredging, or that fishing disturbance has no impact over and above natural physical disturbance within the fishery. An analysis of biological and life history traits revealed that there was no relationship between recent fishing intensity, or BSS, and the functional composition of the communities present. However, even the lowest BSS values in the present study could be considered relatively high compared with areas outside the spatial boundaries of the fishery. Two distinct habitat groups were identified, based on the environmental drivers. These two groups were largely characterized by depth: deep (western) and shallow (eastern) sites. Species with traits that increase resilience to physical disturbance were abundant across all sample sites. Management concerning the environmental impacts of the fishery is discussed in terms of the spatial footprint of the fishery and predicted recovery time-scales for the associated benthic communities.