Research Document - 2008/054

Framework and Assessment for American Lobster, Homarus americanus, Fisheries in the Southern Gulf of St. Lawrence: LFA 23, 24, 25, 26A and 26B

By M. Comeau, J.M. Hanson, A. Rondeau, M. Mallet, and J. Chassé

Abstract

The 2005 lobster (Homarus americanus) stock status of the five Lobster Fishing Areas (LFA) located in the Gulf Region has been assessed using indicators primarily based on a fisheryindependent trawl survey in LFA 25 and part of LFA 26A, SCUBA surveys in LFAs 23, 25, 26A, fishery-based data from DFO official catch statistics, at-sea sampling, voluntary indexharvesters logbooks, voluntary recruitment-index logbooks, and biological sampling. The abundance indicators based on landings of legal size lobster from all LFAs except 25, are close to or above the long-term median. Landings in the central Northumberland Strait (southern half of 25 and western half of 26A) are below the long-term median. Similar trends in abundance were observed based on the fishery-independent trawl survey. The fishing pressure indicators show that most of the catches consist of new recruits (i.e., lobsters growing to commercial sizes and entering the fishery for the first time). There is further evidence that the fishing pressure is too high based on estimates that 50% of traps are empty over the season in four of the five LFAs (LFA 24 had 24%). The production indicators based on pre-recruit logbook program and the trawl survey are negative in Northumberland Strait and positive elsewhere. An increase in berried females catch rates was observed, except in LFA 25 and part of LFA 26A located in the Northumberland Strait. Fishery-independent data (SCUBA) show that the density of 1-2 year olds (<40 mm carapace length) has increased in LFA 23, since 2000. It was low in LFAs 25 and 26A in 2005 and 2006, the only years sampled. The ecosystem indicators show that climatic conditions for the sGSL are warming, and temperature has been rising in all areas. In terms of larval drift and survival, current observations and models suggest that the Northumberland Strait is essentially an isolated system relying on itself for recruitment unlike the rest of the sGSL. In LFA 25, rock crab form the largest part of the lobster diet and the principal predator on lobster is shorthorn sculpin. The lobster fishery continues to rely heavily on the annual recruitment and the exploitation rate remains high. A reduction in the exploitation rate would allow more lobsters to survive to grow to larger size. In LFA 25, the timing of the opening of the fishery overlaps with the lobster spawning period and impedes measures to increase egg production through the protection of berried females. Increases in the minimum legal size in all lobster fishing areas would also lead to increased egg production.

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