Symposium Abstract: The Impact of Scallop Dredging on American Lobster Homarus americanus in the Baie des Chaleurs, Canada
P. Archambault and L. Gendron
Lobster fishers in eastern Canada often complain that scallop dredging is responsible for local declines in lobster landings of the American lobster through destruction of lobster habitat. In Baie des Chaleurs, although scallop dredging is restricted to depths over 18 m to 27 m, depending on the season, it nevertheless occurs in areas where lobster is known to be present at certain times of the year. The aim of this project was to determine to what extent scallop fishery spatially overlaps lobster grounds and to examine the impact of scallop dredging on lobster habitat, more specifically in terms of loss of bottom complexity. Such a loss could affect the survival of lobster at different stages of its life, especially cryptic juvenile stages. The study was concentrated in two localities, for which fisheries managers have received site-specific request to assess the link between these two fisheries. Seasonal adult lobster distribution was examined from lobster fishing activity and from off-season experimental fishing. Location of dredging activities was obtained from scallop fishers logbooks. Habitat, in overlapping areas, was characterized using an acoustic device. Furthermore, abundance of juvenile and adult lobsters was evaluated along transects running across the overlapping area. Additionally, experimental dredging was performed at one depth and a ‘Before-After-Control- Impact design’ was used to identify the immediate impact of the scallop dredge on habitat complexity and benthic community. Results will be discussed in relation to the possible mechanisms explaining how lobster landings could be affected by scallop dredging activity.