California Sea Grant College Program

The California spiny lobster is an ecologically and economically important species in southern California coastal waters. In San Diego County, commercial lobster landings average approximately 500,000 pounds per year with a subsequent value of ca. $5 million, and recreational fishing for lobsters is a valued part of life in San Diego for many people. Lobsters are a major predator of benthic invertebrates along the southern California coastline, and they act as a keystone species by preying upon competitively dominant mussels on rocky shorelines and sea urchins that consume kelp, thereby promoting the existence of diverse shoreline communities. Despite the fact that P. interruptus has supported a fishery in California for over 100 years and may presently be overfished, we have relatively little fishery-independent information on lobster population dynamics and behavior that could be used to implement conservation efforts. Our goal in this research was to fill some of these gaps in our knowledge by determining linkages between spiny lobster habitat and lobster population structure and movement. Specifically, we tested (1) how characteristics of lobster shelter and of benthic landscapes influence lobster shelter selection and their nocturnal foraging behavior; and (2) how risk of predation influences lobster shelter use behavior. By addressing these objectives we evaluated the utility of various habitats as essential fish habitat for lobsters, and we addressed two priorities set out in the California Marine Life Protection Act (MLPA): (1) to assess the home range of exploited mobile invertebrate species, and (2) to provide baseline information on the abundance, size frequency, population structure and location of nearshore invertebrates.