The California spiny lobster ranges from Monterey Bay, California to Manzanillo, Mexico. There is also a small, isolated population of this species at the northwestern end of the Gulf of California. The majority of the population is found between Point Conception, California and Magdalena Bay, Baja California. Adult lobsters usually inhabit rocky areas from the intertidal zone to depths of 240 feet or more.
Spiny lobsters mate from November through May. The male attaches a putty-like packet of sperm, called a spermatophore, to the underside of the female‘s carapace. When the female releases her eggs, she uses the small claws at the end of her last (fifth) pair of walking legs to open the spermatophore and fertilize the eggs with the sperm inside the packet. Fertilized eggs are attached to the underside of the female‘s tail primarily in May and June. “Berried” females are generally in water less than 30 feet deep and carry their eggs for about 10 weeks. The larger the size of the female, the more eggs she produces. Females sampled at San Clemente Island carried between 120,000 (2.6 inches CL) and 680,000 (3.6 inches CL) eggs.
Spiny lobster eggs hatch into tiny, transparent larvae known as phyllosomas that go through 12 molts. They have flattened bodies and spider like legs, and drift with the prevailing currents feeding on other planktonic animals. They may drift offshore out to 350 miles, and may be found from the surface to a depth of over 400 feet. After five to nine months, the phyllosoma transforms into the puerulus or juvenile stage. The puerulus is still transparent, but now looks like a miniature adult with extremely long antennae. The puerulus actively swims inshore where it settles to the bottom in shallow water and starts to grow if the habitat is suitable.
The spiny lobster‘s outer shell serves as its skeleton, and is referred to as an exoskeleton. To grow, a lobster must shed its exoskeleton. This process of molting is preceded by the formation of a new, soft shell under the old one. An uptake of water expands the new shell before it hardens. Lobsters are vulnerable to predation and physical damage right after they molt, until their new shell hardens. Molt rates for the California spiny lobster are assumed to be similar to those of the Japanese spiny lobster. A 0.24-inch CL specimen goes through 20 molts to reach 1.18 inches CL at the end of its first year. Four molts during the second year will result in a carapace length of two inches, and there are three molts in the third year. It takes a lobster from seven to 11 years to reach a legal size of 3.25 inches CL. Spiny lobsters molt annually, following the reproductive period, once they reach 2.5 inches CL. Growth rates, or the period between molts, are highly variable. They have been correlated with food availability, size, and sex. The larger an animal, the slower it grows. Injuries or disease will often result in a slowing or complete cessation of growth until the injury has been repaired.
Juvenile lobsters usually spend their first two years in near shore surf grass beds. Sub-adults have also been found in shallow rocky crevices and mussel beds. Adult lobsters are found in rocky habitat, although they also will search sandy areas for food. During the day, spiny lobsters usually reside in a crevice or hole, dubbed a den. More than one lobster is usually found in aden. At night, the animals leave their dens to search for a wide range of food. Adult lobsters are omnivorous and sometimes carnivorous. They consume algae and a wide variety of marine invertebrates such as snails, mussels, sea urchins, and clams as well as fishes, and injured or newly molted lobsters. Lobsters are eaten by sheep head, cabezon, kelp bass, octopuses, California moray eels, horn sharks, leopard sharks, rockfishes and giant sea bass.
A large portion of the spiny lobster population makes an annual offshore-onshore migration that is stimulated by changes in water temperature. During winter months, male and female lobsters are found offshore at depths of 50 feet and deeper, although individuals of both sexes have also been found in shallow water in winter. In late March, April, and May, lobsters move into warmer onshore waters less than 30 feet. The higher temperatures on shore shorten the development time for lobster eggs. Nearshore waters also have a more plentiful supply of food. In late October and November, the onshore waters cool, and most lobsters move offshore. Winter storms that cause increased wave action in shallow water encourage this movement. Lobsters generally move after dark and in small groups across the sand.
California spiny lobsters of both sexes reach maturity at five or six years and 2.5 inches CL. After maturity, male lobsters grow faster, live longer, and reach larger sizes than the females. Males can live up to 30 years, and females at least 20 years. There are records of male California spiny lobster weighing over 26 pounds and attaining lengths up to three feet. Today, lobsters over five pounds are considered trophy-size. Trophy-size animals are usually taken by recreational divers. The closed season protects egg-carrying and molting female lobsters. The size limit ensures that there will be several year classes of brood stock, even if all legal-size lobsters are caught each season.
Article excerpts used courtesy of the California Department of Fish and Game.