Growth increment and molt frequency of the American lobster (Homarus americanus) in the southwestern, Gulf of St. Lawrence

The growth increment and molt frequency of the American lobster (Homarus am ericanus) ranging in size from 46 to 154 mm of carapace length (C-L) from t he southwestern Gulf of St. Lawrence (sGSL) were investigated by tagging an d trap studies. The main molting period for lobster in sGSL was from early July to early September. Evidence for two molting seasons was observed only for male lobsters in Malpeque Bay, Prince Edward Island, and Baie des Chal eurs (Northeastern New Brunswick), but there was little evidence of double molting (< 0.2%). Evidence of animals skipping their annual molt was observ ed throughout sGSL. The percentage of growth increment for lobsters of the same sex tagged in premolt was significantly less than lobsters tagged in p ostmolt. The lower average percentage of growth increment observed for lobs ters tagged in premolt is believed to be related to tagging trauma which is likely greater for lobsters actively developing a new carapace prior to mo lting. Male lobsters had significantly larger molt increments than females. Comparison between Malpeque Bay and Baie des Chaleurs yielded significant differences in the growth for male and female lobsters but not for berried females. The lowest average percentage of growth increment (12%) was observ ed for berried females. Furthermore, no relationship was observed between t he growth increment and C-L.