Symposium Abstract: Reduction of Species Diversity in a Cobble Habitat Subject to Long-Term Fishing Activity
L. Watling and A. Pugh
Studies dealing with the impact of mobile fishing gear have, for the most part, been conducted in areas with low fishing disturbance and are conducted using the BACI design. There have only been a few studies where bottoms that have been fisihed routinely are compared with neighboring unfished areas. We examined an area in 100 m water in the Gulf of Maine that had been fished with otter trawls for white hake and compared the epifaunal community with that of an adjacent area that was too rough for fishing even with rock-hopper gear. In both areas, boulders with relatively flat surfaces were chosen for scraping and suction-sampling with an ROV. There were far more species at the untrawled site as compared with the trawled site. All other measures of diversity, including speciesarea curves, showed a reduction in diversity at the trawled site of about 50%. Cluster analysis showed almost no similarity between the two sites. For the most part, the presence of large, tree-like hydroids and bryozoans, present at the unfished site and absent at the fished site, provided additional habitat for many of the smaller invertebrates sampled.