TEMPORAL PATTERNS OF REPRODUCTIVE CONDITION IN THE DOUGHBOY SCALLOP, CHLAMYS (MIMACHLAMYS) ASPERRIMA LAMARCK, IN JERVIS BAY, AUSTRALIA

The broodstock reproductive condition of doughboy scallops, Chlamys (M imachlamys) asperrima Lamarck, in Jervis Bay, Australia, was monitored fortnightly for 2 y. Gonosomatic index (GSI), gonad weight, and macro scopic gonadal appearance were used to assess changes in the reproduct ive status of the population. In common with C. asperrima in Tasmania, a winter-spring peak in reproductive activity was observed, although macroscopically ripe (mature, ready-to-spawn) individuals were present in most collections. Peaks in reproductive indices occurred in June a nd August 1992 and in September 1993, during which partial spawning wa s evident. Male and female development was synchronous, although femal e scallops maintained higher GSIs and macroscopically higher levels of gonadal development and, at their reproductive peak, had higher calor ific values for gonadal tissue. Female gonads were also consistently h eavier than those of equivalent-sized males, although adductor muscle weight in males was on average 9% heavier than that of females. Observ ations of reproductive condition indicate that although the optimal ti mes for the harvest of C. asperrima in Jervis Bay are likely to be sim ilar to that of southern stocks, the presence of reproductively capabl e individuals at most times of the year in Jervis Bay could be of adva ntage in the hatchery production of the species and in the provision o f embryos for ecotoxilogical studies.