Changes in Size Distribution of Snow Crabs ( Chionoecetes opilio ) in the Southwestern Gulf of St. Lawrence

Abstract

Size distributions of the exploited snow crab (Chionoecetes opilio) population in the southwestern Gulf of St. Lawrence were obtained from commercial landings in New Brunswick ports during 1977-82. The unexploited part of the stock was sampled during research vessel surveys in 1980 and 1981. The size distributions were analyzed by factorial analysis of correspondence. The trend in mean size was negative from 1977 to 1981 and positive thereafter. The analysis identified two periods of recruitment to the standing stock within each year; the first at the beginning of summer and the second in late summer and autumn. Growth of the previously-recruited crabs occurred between these two periods. Analysis of research vessel data indicated that many prerecruits inhabited areas outside the usual fishing grounds. The hypothesis is proposed of recruitment by platoons, with a part being due possibly to migration of crabs from shallow unexploited areas to deeper water where the commercial fishery occurs.