Life History 



The reproductive cycle of the American lobster is typical of crustaceans. The 

 sexes are separate, and copulation occurs immediately after the female molts, 

 usually in early summer or fall. The female stores the sperm in her body from 

 2 weeks to 15 months before the fertilized eggs are extruded (Cobb 1976). 

 Thomas (1973) estimates that eggs are released by the female between May and 

 July in coastal Maine lobster populations. The age and size of a female 

 determines the number of eggs produced. Approximately 10,000 eggs are 

 produced by a 1 lb lobster, and 130,000 by an 18 lb lobster (Perkins 1971). 



The fertilized eggs are held on pleopods (appendages) on the female's 

 underside until the following summer, when they hatch. Under laboratory 

 conditions the mortality rate of the eggs until hatching is about 35% (Perkins 

 1971). The length of the hatching period depends on temperature. In the 

 laboratory at optimum temperature of 68°F (20°C) , hatching will occur in 16 

 weeks; 39 weeks are required at 50°F (10°C; Hughes and Matthiesen 1962; and 

 Cobb 1976). Hatching period and mortality rate of eggs under natural 

 conditions are unknown. 



Immediately after hatching, larvae assume a planktonic (suspended in the water 

 column) existence in Maine waters that lasts from 5 to 6 weeks. They are 

 subjected to the biotic and abiotic stresses of the water column environment. 

 As in all arthropods, which have hard outer shells, growth in American 

 lobsters is achieved through molting. Larval lobsters molt four times before 

 settling to the bottom. 



On assuming a benthic existence, lobsters are considered juveniles. In Maine, 

 approximately 10 molts (4 as larvae) occur in the first year, after which 

 juveniles molt two or three times per year. After the fifth year, molting is 

 annual (usually mid-summer to early fall) but it may be biannual for adult 

 females who are carrying eggs. In mature lobsters each molt results in 

 increases in length of up to 14% (Cobb 1976). 



Warm temperatures increase the growth rate of lobsters. The fastest-growing 

 individuals may reach sexual maturity in 4 years, but most do not mature until 

 they are 5 to 7 years old. Krouse (1972) found that in Maine male lobsters 

 mature at smaller sizes than females. Fifty percent of the males may be 

 mature at 1.7 inches (44 mm) carapace length, whereas few females mature until 

 they have exceeded the minimum length legal for harvest, 3.1 inches (81 mm). 

 Thomas (1973) estimates that in Maine females mature at a size between 3.5 and 

 3.9 inches (90 and 100 mm). Lobsters can live for over 20 years. 



The diet of lobster is flexible and includes crustaceans (e.g., crabs) 

 molluscs (e.g., small clams), echinoderms, algae, and hydroids. It has been 

 estimated by Miller and coworkers (1971) that the American lobster in Nova 

 Scotia consumed approximately 10% of the secondary production in the community 

 studied. 



Habitat Preferences 



Lobsters are found principally in the marine system and high salinity areas 

 (>20 ppt) of the estuarine system. 



12-15 



10-80 



