The California spiny lobster is an important species in California both economically and ecologically. In order to support sustainable fishing of this species, managers need more information about reproduction, including female lobster size at maturity and fecundity, as well as a better grasp of the genetic diversity of the population and how many small, “sub-legal” lobsters die during handling in the commercial fishery.
It is also believed that a significant portion of the California lobster stock is spawned in Mexican waters, which means that in order to make sustainable management decisions, an improved understanding of transnational variation in lobster demographics and potential population structures is needed.
Through a sampling program conducted in collaboration with commercial lobster fishers throughout Southern California and northern Baja California, Mexico, this project proposes to improve understanding of California spiny lobster population dynamics and fishery interactions at a regional scale. The researchers collected 6,500 lobsters over two years and counted and measured the eggs from 130 female lobsters.. The resulting estimates increase the probability of maturity at smaller lobster carapace lengths and increase size-specific fecundity values. Additionally, the data shows that lobsters are more fecund in northern areas (Orange County and the Channel Islands) than in southern areas (San Diego and Baja California Mexico). This is true even when adjusting for the fact that lobsters are larger on average in northern regions.
Hovel’s team conducted genetic analysis of tissue samples from 600 lobsters to quantify the genetic diversity of spiny lobsters. While there was little evidence of genetic differentiation between individuals from San Diego and Santa Barbara, individuals from Bahia Tortugas, in Mexico, did show significant differences from the California populations.
Finally, the project team collected approximately 550 tissue samples from other organisms in the kelp forest for analysis. These samples from the kelp forest ecosystem helped establish a food web structure, which affirmed earlier results: lobster dietary niche breadth is very consistent across regions in Southern California and between juvenile and adult lobsters. In San Deigo, lobster diets are dominated by sea urchins, but abundant species of gastropods appear to dominate lobster diet in other regions, and general the diets are varied.