Female lobsters produce tens of thousands of eggs, but very few survive to adulthood. This complex journey is influenced by many natural processes and environmental factors. Early life stages in the marine environment face numerous obstacles.
The Initial Stages of Lobster Reproduction
Lobster reproduction begins when a female, typically in a soft-shell state after molting, mates with a male. She can store the male’s sperm for an extended period, sometimes up to two years, before fertilizing her eggs. When ready, the female extrudes thousands of eggs, fertilizing them as they pass from her ovaries. These newly fertilized eggs then attach to the fine, glue-like hairs on her swimmerets, located on the underside of her tail. She carries these eggs externally for an extended incubation period, which can last between 9 to 13 months, depending on water temperature. During this time, the female is often referred to as “berried” due to the appearance of the egg mass. She actively cares for the eggs by fanning them with her swimmerets to provide oxygen and keep them clean. A one-pound female lobster might carry around 8,000 eggs, while a larger, nine-pound female can carry over 100,000 eggs.
Environmental and Predatory Challenges
Once hatched, lobster larvae face significant threats from their environment. These microscopic larvae float near the ocean surface for several weeks, making them susceptible to adverse conditions. Fluctuations in water temperature, changes in salinity, and strong ocean currents can disperse larvae away from suitable habitats, hindering their development and survival. Climate change, for instance, affects ocean temperatures, which can impact larval growth rates and swimming abilities. Predation is another major factor in the high mortality rates of lobster eggs and larvae. While still attached to the female, some eggs can be dislodged or consumed. However, the free-swimming larval stages are particularly vulnerable to a wide array of predators. Fish such as cod, haddock, dogfish, and skate prey on young lobsters, as do various seabirds like gulls that target larvae near the surface. Even other crustaceans, including larger lobsters and crabs, contribute to predation.
The Drastic Drop in Survival Rates
The transition from egg to adult lobster involves an exponential reduction in numbers across successive life stages. After hatching, the larvae spend approximately four to six weeks floating in the water column, during which they undergo multiple molts. This pelagic phase is when mortality rates are exceptionally high, with only a small fraction of larvae surviving to settle on the ocean floor. Estimates indicate that from every 50,000 eggs laid, only about two lobsters are expected to reach legal harvesting size. Some studies suggest that fewer than 10% of hatched eggs even reach the juvenile stage.
Human Roles in Lobster Egg Survival
Human activities significantly influence lobster egg and larval survival, encompassing both detrimental impacts and conservation efforts. Negative influences include habitat degradation, which can destroy crucial nursery grounds for juvenile lobsters, and the broader effects of climate change, such as warming ocean temperatures and acidification that stress larval development. Overfishing can also reduce the overall breeding stock, impacting the number of eggs produced in the population. Conversely, conservation practices play a positive role in protecting lobster populations. One such measure is “v-notching,” where a small V-shaped notch is cut into the tail of an egg-bearing female lobster before she is released back into the ocean. This mark identifies her as a reproductive female, making it illegal for her to be harvested, ensuring she can continue to contribute eggs to the population. Minimum and maximum size limits for caught lobsters also protect both young, immature individuals and large, highly reproductive females. Additionally, the establishment of marine protected areas (MPAs) can provide safe havens where lobsters can grow larger and produce more eggs without fishing pressure, contributing to increased reproductive output.