Assessment of the impacts of mobile bottom-contacting fishing gears on epibenthic communities of the Scotian Shelf and Gulf of Maine (Atlantic Canada)

An assessment of the impacts of mobile bottom-contacting gears (MBCG) on eight previously identified epibenthic communities off Nova Scotia, Canada, is presented using risk-based indicators of relative Benthic status (RBS). Indices of both existing biomass relative to carrying capacity of the whole epibenthic community (RBStot), and that of the 10% most sensitive fauna (RBSsen), were quantified and mapped. Substantial regional and habitat-related differences in RBS were identified. Most of the eastern Scotian Shelf, where five benthic community types are recognized, showed low fishing intensity and high seabed status. In contrast, a community characterized by long-lived individuals of echinoderms, sponges, and cnidarians on eastern Georges Bank and in the Inner Bay of Fundy, was severely impacted. RBStot for that community was in good status on only 48% of the area of the habitat, while RBSsen met that threshold on only 35% of the area. Our approach allows for the large-scale evaluation of the impacts of MBCG on the benthic communities as a whole and enables evaluation of management scenarios aimed at reducing its environmental effects.