Fishing impact on deep Mediterranean rocky habitats as revealed by ROV investigation

Deep-water fishing activities are impacting deep-water habitats worldwide, yet the extent of the damage caused is mainly unseen and not quantified. We used Remotely Operated Vehicle surveys to assess the extent of fishing impacts on rocky substrata on four offshore banks between 70 and 280 m depth in the Mediterranean Sea. Video analysis of the abundance and diversity of megafauna revealed communities dominated by arborescent cnidarian passive suspension feeders at all studied depth ranges. Between 19% and 62% of the video frames showed clear impacts from lost debris, the majority of which is ascribable to both professional and recreational fishing activities and the occurrence of fishing impact is generally correlated with the presence of entangled and overgrown corals. Broken coral colonies and strips where habitat-forming species were scattered provided additional evidence of widespread fishing disturbance. These data evidence the widespread impact of fishing activities on benthic hard bottom communities and suggest the need of specific conservation measures in coastal and off-shore management plans at both local and national levels in order to protect unique ecosystems that are progressively disappearing even before being studied.