9781888569605-ch143

Benthic Habitats and the Effects of Fishing

The Impact of Demersal Trawling on Northeast Atlantic Deepwater Coral Habitats: The Case of the Darwin Mounds, United Kingdom

A. J. Wheeler, B. J. Bett, D. S. M. Billett, D. G. Masson, and D. Mayor

doi: https://doi.org/10.47886/9781888569605.ch143

Abstract. Deepwater corals form reefs and carbonate mounds that are important biological habitats along the European continental margin. Recent mapping of these features has highlighted significant habitat impact resulting from demersal trawling. With the current expansion of European deepwater fisheries, the potential for further coral habitat damage will increase. Seabed observations (100kHz side-scan sonar, still, and video imagery) are presented here that document trawling impacts on the Darwin Mounds, a field of small, coral-topped mounds at c.1,000 m water depth in the northern Rockall Trough. Comparisons between trawled and nontrawled mounds are startling. Trawl marks are clearly visible on side-scan sonar records, with visual imagery showing higher abundance of dead coral and coral rubble at trawled sites compared to untrawled sites. Some of the seabed in the Darwin Mound areas has been intensely trawled, with local areas at a scale resembling the distance between trawl doors being 100% trawled. Some areas show evidence for multiple trawling events. Coral habitat destruction can occur on a scale that impacts the coral growths on entire coral mounds. The conflict between deepwater fisheries and habitat protection in the European Atlantic Margin is discussed.