How many eggs do females of difference sizes produce?
Estrella and Cadrin (1995) estimated the relationship between fecundity and size using the following equation:
Fecundity = (0.000605 * CL^3.7227)
This estimates that a female with 83mm or 3 1/4" carapace length (a chick lobster) produces about 8,400 eggs and a female with 100mm or 5" carapace length (3 1/2 lbs) produces about 17,000 eggs. It is also thought that larger (>120 mm) lobsters produce eggs with a higher energy content (Attard and Hudon, 1987) and that the larvae from these eggs may have a better survival rate.
How long do females carry their eggs?
Generally it takes from 9-12 months from the time that the female extrudes her eggs onto her abdomen to the time when they hatch as larvae (Talbot and Helluy, 1995). Hatching usually occurs between May and September.
Do lobsters migrate?
Tag and recapture studies have shown that lobsters tagged offshore in the winter and spring have been recaptured inshore in the summer and fall and vice versa (Cooper & Uzmann, 1971, 1980; Fogarty et al., 1980; Campbell et al., 1984; Aiken & Waddy, 1986; Pezzack & Duggan, 1986). Cooper (1977a) estimated that 20-50% of offshore lobsters are migratory. This suggests a pattern of seasonal migration where lobsters move offshore in the winter and spring and inshore in the summer and fall. The existence of a seasonal migration is supported by population density studies. The highest density of offshore lobsters in the summer and fall months is in inshore or shoal water, whereas in the winter and spring it is in the deep waters of the continental shelf edge (Fogarty et al., 1982).
Movements of larger lobsters to deeper water have also been observed. Skud and Perkins (1969) found shallow populations of smaller, prerecruit lobsters, and deep populations of large lobsters in Veatch canyon. They proposed that lobsters may move to deeper waters as they grow.
How far do lobsters migrate?
Lobsters exhibit different patterns of movement at different stages in their life history. For example, juvenile lobsters do not generally exhibit large scale movements. Campbell & Stasko (1986) found that immature lobsters did not display the same seasonal movements as mature lobsters, but instead exhibited more localized movements along the coastline. In their study, lobsters that were tagged as juveniles began to exhibit these seasonal movements only in later recaptures (1.5 years after tagging) as they were nearing maturity. Lawton & Lavalli (1995) also noted that movement by adolescents (40-45mm) was usually less than 300m. Several other studies have supported the theory that larger mature lobsters move greater distances (Saila & Flowers, 1968; Cooper & Uzmann, 1971; Morrissey, 1971; Dow, 1974; Campbell & Stasko, 1986) than immature lobsters.
Mature lobsters have an average annual range of about 32km (Campbell and Stasko, 1985; Campbell, 1986). This average represents a small number of lobsters that migrate very long distances and a large number that undertake shorter movements. Inshore lobsters typically move more locally (Briggs & Mushacke, 1979; Fogarty et al., 1980; Krouse, 1981), with the exception of a small number that undertake long migrations along the coast (rather than between inshore and offshore areas). One "long-shore" migrant moved 798 nautical miles in 3 1/2 years (Campbell and Stasko, 1986). Offshore lobsters often undertake seasonal migrations and have been known to move 345km in 71 days (Uzmann, et. al., 1977).
How do lobsters mate?
Lobsters usually mate when the female has just molted. Mating occurs within 24 hours of molting and often within 30 minutes (Talbot and Helluy, 1995). During mating the male deposits a spermatophore, or packet of sperm) into the seminal receptacle of the female. The female must fertilize and extrude her eggs before molting again, or else the sperm is lost when she molts.
Can females extrude multiple broods of eggs between molts?
Yes. This is called consecutive spawning. Large females can spawn twice between molts, since they molt less frequently than smaller females (Waddy et al, 1995). Because they must molt to mate, they may be capable of storing sperm for fertilizing a second batch of eggs.
How do lobsters develop from larvae to adults?
Once the eggs hatch the lobsters go through four stages before settling to the bottom as postlarvae. The first three stages are planktonic and the larvae are found throughout the water column (Harding et al, 1987). At this point they develop into postlarvae and can swim for 10-30 days on the surface before settling on the bottom (Cobb et al, 1989).
How does temperature affect larval development?
The time between hatching and settlement as fourth stage postlarvae varies with temperature. It takes 10 days at 22-24C and almost two months at 10C. Below 5C they usually don't survive (Templeman, 1936).
Do lobsters have a preferred temperature?
Lobsters prefer temperatures between 8-14C. Tagged lobsters that were recaptured after migration had moved into areas in this temperature range (Uzmann et. al., 1977).
What do lobsters eat?
Lobsters are omnivores and their diet varies depending on the availability of different kinds of food. They usually feed on a combination of crabs, molluscs, polychaetes, sea urhcins, and sea stars (Ennis, 1973; Carter and Steele 1982a, 1982b; Weiss, 1970) as well as live fish and macroalgae. They also are known to be cannabilistic. However, in areas with a large number of lobster traps bait fish, primarily herring and mackerel, comprise a large portion of their diet.
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