Local Differences in the Life History of the Lobster (Homarus americanus) on the Coast of the Maritime Provinces of Canada

The hatching and moulting of the lobster are earlier in waters with a high than in those with a lower summer temperature. Moulting is about one week later for each degree lower summer temperature. In such high temperature areas as Malpeque bay two moultings occur during the year in most lobsters between 14 and 22 cm. in length. In the whole southern gulf of St. Lawrence area female lobsters as small as 18 to 21 cm. in length may carry eggs, while in the Grand Manan area with a summer temperature 5 to 8 °C. lower, the smallest sexually mature females are about 34 cm. in length. The growth per moult of the female lobster falls considerably below that of the male when sexual maturity approaches, thus in the southern gulf of St. Lawrence the female growth rate slows down rapidly after 18 to 21 cm. and in southern Nova Scotia at about 30 cm. In the southern gulf area at small sizes more males than females appear in the commercial catch, at larger sizes more females and at very large sizes nearly all the lobsters caught are males. Average sizes of lobsters in the commercial catch are considerably smaller in the southern gulf area than in southern Nova Scotia and at Grand Manan.