The Spawning Habits of Spiny Lobsters in San Francisco Bay, California

Spiny lobsters are found on the southern coastlines of Central and North America, from Florida to California and as far south as Bermuda. Though they are easily identified as lobsters, they lack the large pincers that so often define these animals. Rather than relying on their claws, spiny lobsters protect themselves from predators with their antennae and shell spines, particularly during the mating season, when they are most vulnerable.

  1. Choosing a Location

    • Spiny lobsters in the San Francisco Bay area retreat into deeper parts of the ocean for the winter. However, during the mating season in the spring months (generally between March and June), they move toward the warmer, shallower bay area. There, they mate in sheltered crevices and reef material to protect themselves. The lobsters must also see the area as being a safe place to bring up their young, so it must be away from large fish, eels and sharks.

    Frequency

    • Spiny lobsters in the tropics may mate several times in a year. However, in San Francisco, the water temperature is not warm enough for them to do this. Therefore, they only have one mating season. However, male lobsters may mate with several different females over the course of the season. The males who do this are the alpha males in a colony. The resident beta males may not mate at all, as the alpha is very territorial.

    Mating

    • Females reach sexual maturity from the ages of five to nine years old, while males reach maturity from three to six years of age. However, their level of maturity is determined by their size. Females mate just after their molt occurs, and they rely on their alpha male to protect them until their exoskeletons harden. To fertilize the female's eggs, a male lobster deposits a ball of sperm called a tarspot on her chest. She then releases her eggs while scratching at the tarspot to fertilize the eggs.

    Spawning

    • The females carry their eggs with them for 10 weeks, protecting the eggs under their tails. The eggs start off coral-colored, but harden and take on a maroon hue as they grow closer to hatching. Females may lay as many as 680,000 eggs, as most of the larvae will not grow into adulthood. To spawn, the females turn up their tails after the eggs reach maturity, releasing them to the undersides of vegetation. In the San Francisco Bay area, spawning takes place from May to August, depending on when the females mated.