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Research Document - 2001/111

Current knowledge on the commercially import invertebrates (lobster and snow crab) in the proposed oil and gas exploration site and adjacent area (southern Gulf of St. Lawrence and Sidney Bight)

By Moriyasu, M., Davidson, L.-A., Lanteigne, M.,
Biron, M., Comeau, M., Hébert, M., Savoie, L., Surette, T., Wade, E., and C. Sabean

Abstract

A summary of current knowledge on the life cycle, the fishery, and the biology of the American lobster (Homarus americanus), the sea scallop (Placopecten magellanicus), and the snow crab (Chionoecetes opilio) in the proposed oil and gas exploration site (Western Cape Breton and Sydney Bight) and adjacent areas is presented. For lobster, moulting and mating seasons generally occur between July and September. Larval hatching and settlement occur in July-August and August-November, respectively. For scallop, the fertilization of gametes occurs in late August and spat settlement in late September to October. For snow crab, moulting occurs between December and March and mating in February and May. Larval hatching and settlement occur in May and August-October, respectively.

Within the concerned oil and gas exploration and adjacent area, lobster is commercially exploited in Lobster Fishing Area (LFA) 26B at depths shallower than 40 m, scallop in SFA 24 at depths from 20 to 40 m, and snow crab in Crab Fishing Areas (CFAs) 12 and 18 to 22 at depths between 50 and 200 m. Tag-recapture studies showed that lobsters are relatively sedentary, especially in LFA 26B, whereas an active movement pattern was observed in snow crab. For lobster, the commercial catches in LFA 26B have been stable around 1000 t since 1993. Although LFA 26B is a small fishable surface, it is the most productive LFA among the southern Gulf of St. Lawrence lobster fisheries. Scallop Landings in Scallop Fishing Area (SFA) 24 have been fluctuating between 100 t and 200 t since 1974. For snow crab, the exploitable biomass has been continuously increasing in CFA 19 since 1996 and exceeded the 6,000 t level in 2000 (survey year). In eastern Nova Scotia, the catch rate has been increasing significantly in the northern CFAs (CFA 20, 21, and 22) since 1996. No lobster fishing activities occurred within the proposed oil and gas exploration survey sites, whereas snow crab was actively exploited in both southeastern Gulf of St. Lawrence and Sydney Bight. In addition, both sites include important reproductive areas for snow crab (concentration of ovigerous females, juvenile males, and possible settlement sites of larvae). For lobster and scallop, the main habitat of post-larval lobster is far from the proposed seismic survey sites. Only during the planktonic larval phase, may lobster and scallop be found within the survey sites. No scientific information is available regarding the impact of the seismic survey on those three species. However, more direct and immediate impact, if any, may be expected on snow crab than on lobster or scallop.

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