Growth slows down progressively as the juvenile lobster grows to adulthood. Since lobsters grow faster in more temperate waters they may moult more often. In the Northumberland Strait, for example, where summer water temperatures may reach 20 C, a lobster at the current canner minimum of 63.5 mm carapace length, can moult twice in one year. Once a lobster has replenished the flesh within its new shell, it will be about 50 per cent heavier than before a moult. So in one year a lobster from the Northumberland Strait would grow from 200 g to 450 g, and would moult twice, whereas his counterpart in a cooler habitat would average 300 g, and moult only once.
Temperature is also a factor in the age at which a lobster attains sexual maturity.
700 g or eight years of age. The size at which the average female is mature and capable of producing eggs to replenish the population is very important in the regulation of the fisheries harvest, because if females are not given the chance to contribute to the reproduction of the species, the lobster population will obviously suffer a decline. This is the main problem facing the lobster population today. Once on the sea bottom, the still vulnerable juveniles are so secretive that divers cannot accurately estimate their numbers. It is logical to suppose that mortality diminishes rapidly as lobsters become larger and better able to defend themselves.