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Canadian Science Advisory Secretariat
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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