This publication examines recent experimental studies of the impact of towed fishing gears, such as trawls and scallop dredges, on benthic habitats and communities (organisms that live at or near the bottom of the sea). The review gives a critical evaluation of the methodological limitations of impact studies, given the complexity and natural variability of benthic communities.

Concerns over the potential ecological effects of fishing have increased with the expansion of fisheries throughout the marine waters of the United States. Effects of Trawling and Dredging on Seafloor Habitat describes how assessment of fishing impacts depends on gear type, number and location of bottom tows, and the physical and biological characteristics of seafloor habitats. Many experimental studies have documented acute, gear-specific effects of trawling and dredging on various types of habitat. These studies indicate that low mobility, long-lived species are more vulnerable to towed fishing gear than short-lived species in areas where the seabed is often disturbed by natural phenomena. Trawling and dredging may also change the composition and productivity of fish communities dependent on seafloor habitats for food and refuge. The scale of these impacts depends on the level of fishing effort. This volume presents color maps of fishing effort for all regions with significant bottom trawl or dredge fisheries-the first time that such data has been assembled and analyzed for the entire nation.

A national science peer review was held 22-24 March 2006 at the Queen Elizabeth Hotel, Montreal, Quebec. The purpose of the meeting was to review the scientific information available from international studies and Canada's research in relation with the impacts of mobile bottom gears on Canadian benthic habitats and communities. This meeting considered only the mobile bottom-impacting gears, specifically otter trawls (defined broadly), scallop dredges, and hydraulic clam dredges. The main working paper submitted at this peer review was a synthesis from five major international reviews or symposia conducted on the impacts of mobile bottom gears on seafloor habitats, species, and communities, in the early part of the 2000's. Seven other working papers dealing with the recent research done in Canada on trawl impacts on seafloor habitats, or describing what is presently known about the nature and distribution of benthic habitats in Canada were also presented.

This publication examines recent experimental studies of the impact of towed fishing gears, such as trawls and scallop dredges, on benthic habitats and communities (organisms that live at or near the bottom of the sea). The review gives a critical evaluation of the methodological limitations of impact studies, given the complexity and natural variability of benthic communities.