GROWTH AND MATURATION OF THE BENTHIC STAGES OF MALE SNOW CRAB, CHIONOECETES-OPILIO (BRACHYURA, MAJIDAE)

Growth and maturation of postlarval male snow crab (Chionoecetes opilio) in an exploited Gulf of Saint Lawrence population were elucidated using size distributions in beam trawl samples taken bimonthly from April 1991 to May 1992, moult and maturity indices, and measures of growth per moult. Males develop in three stages: immature, without spermatophores; adolescent, with spermatophores but undifferentiated chelae; and adult, with spermatophores and differentiated chelae. Males change from immature to adolescent after a puberty moult, and from adolescent to adult after a terminal moult producing a final carapace width (CW) >40 mm. The slope of the regression relating post- to pre-moult CW decreases after puberty. Carapace moult increments are the same at pre-terminal and terminal moults, for a constant premoult CW. Males recruit to the legal size of 95-mm CW at instar XII, approximate to 8.7 years or more after settlement. The slope of the regression of gonad weight on CW is less for adult than for adolescent males owing to the formers' participation in reproduction and to greater depletion of sperm stores in large than in small adult males. Gonad weight increases with time since moult, but for large adults, did not reach levels recorded in prefishery times or in an unfished population.