Molt timing and growth of the lobster, Homarus americanus, off northeastern Cape Breton Island, Nova Scotia

Seasonal changes in molt condition, together with mark-recapture data, were used to estimate molt timing and growth of adolescent and adult lobsters (Homalus americanus) in the St. Anns Bay area (northeastern Cape Breton Island) in 1993 and 1994. In both years, most molting occurred between late Jul:, and early September. Within the larger sizes (>70 mm CL), males molted earlier than females, but there was extensive overlap in their molting periods. Annual differences in molting time were apparent and were linked to bottom temperature. Double moiling of individual lobsters was rare and limited mainly to prerecruit lobsters. From spring to autumn, there were substantial changes in trap catch rate, size composition. and sex ratio. Males dominated the catch in late summer and fall, probably because they molted earlier than females. Within-season and between-year changes in catchability associated with molting need accounting if trap catch rates are to be used as indices of lobster abundance and for estimation of exploitation rate.