Research Document - 2006/056

A review of Maritimes Region research on the effects of mobile fishing gear on benthic habitat and communities

By Gordon, D.C. Jr., E.L.R. Kenchington, and K.D. Gilkinson

Abstract

In collaboration with the Newfoundland & Labrador Region, the Maritimes Region has conducted an extensive field program to provide quantitative information on the effects of bottom-contacting mobile fishing gear on benthic habitat and communities. This research has included carefully designed manipulative experiments as well as observational and laboratory studies. The three major gear types used in Atlantic Canada have been studied (otter trawls, scallop dredges and hydraulic clam dredges). Impacts on both sand and gravel habitats have been investigated, but not mud habitats. Geographic areas considered include the Bay of Fundy, Northeast Channel, Western Bank, Banquereau, Laurentian Channel and the Grand Bank. The results provide information on immediate impacts (recovery < 1 y), short-term impacts (recovery 1-10 y), and long-term impacts (recovery >10 y). With just a few exceptions, the results have been subjected to peer review and published in the scientific literature (the last few reports are being drafted). They illustrate that the impacts of bottom-contacting mobile fishing gear are extremely variable and depend upon many factors including the kind of gear, how it is used, the return period of the disturbance, the kind of physical habitat and the species composition of the benthic community. Sandy habitats are easier to disturb but are faster to recover than gravel habitats. The most sensitive species are large epibenthic forms, especially those that are sessile and have slow growth rates. The results are in general agreement with the conclusions reached from recent international reviews on this issue with the exception that not all gravel habitats may be as sensitive as generally thought. The impacts of bottom-contacting mobile fishing gear is an important issue that needs to be considered as Canada moves to adopt an ecosystem approach to fisheries management. The most effective management measures are effort control, gear modification and substitution, and establishment of closed areas. The best course for action needs to be decided with input from all stakeholders (i.e. scientists, fisheries managers, habitat and ocean managers, industry, coastal communities, NGOs, etc.).

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