Effects of Fisheries on Deepwater Gorgonian Corals in the Northeast Channel, Nova Scotia
Pal B. Mortensen, Lene Buhl-Mortensen, Donald C. Gordon, Jr., Gordon B. J. Fader, David L. McKeown, and Derek G. Fenton
Abstract. Video surveys in the Northeast Channel, Nova Scotia, between Georges Bank and Browns Bank in the Northwest Atlantic, were conducted to determine the distribution of deepwater corals and extent of damage from bottom fishing activities. Three gorgonian species, Paragorgia arborea, Primnoa resedaeformis, and Acanthogorgia armata, were observed between 190-m and 500-m depths (the maximum working depths of the video equipment). Paragorgia arborea and Primnoa resedaeformis occurred along 21 and 35 of the 52 transects, respectively, whereas Acanthogorgia armata was observed on only 4 transects. The colonies grow on cobbles and boulders in glacial deposits and often have both mobile and sessile associated species, including fishes. The Northeast Channel is an important fishing area targeted by otter trawling and longline and gill-net fleets. Signs of fishing impact were visible as broken live corals, tilted corals, and scattered skeletons. Lost fishing gear was often observed entangled in corals. Broken or tilted corals were observed along 29% of the transects. In total, 4% of the coral colonies observed were impacted. Paragorgia arborea seems to be more susceptible to breakage from encounters with fishing gear than Primnoa resedaeformis. This is most likely due to its larger size and less flexible skeleton. Using the results of this study, the Department of Fisheries and Oceans established a 424-km2 coral conservation area in 2002 to protect corals from further damage from bottom fishing activity.