A biological hotspot resides off California’s southern coast at La Jolla, characterized by dense kelp forests, surfgrass beds, hard- and soft-bottom deep water habitats, and both sandy beaches and rocky shores. To protect this ecologically diverse area, the California Fish and Game Commission adopted the South La Jolla State Marine Reserve (SMR) as a marine protected area (MPA) in January 2012.
The implementation of the statewide MPA network introduced a new approach to marine resource management. Previously, marine life was dependent upon single species conservation measures or de facto refuges for protection; now, MPAs act in concert with single-species protections to bolster and improve ocean health on an ecosystem level.
One of the species likely to benefit from the protections afforded by MPAs is abalone. Only recreational free divers can take red abalone north of San Francisco Bay, while fishing for and taking abalone south of San Francisco Bay is prohibited. MPAs can provide additional protections across the entire food web that abalone depend upon, thus enhancing the protections afforded by the prohibition on abalone fishing south of San Francisco Bay.
In the past, central and southern California supported popular recreational and lucrative commercial fisheries for red, pink, black, white, and green abalones. However, human-induced and natural stressors negatively affected abalone stocks there, causing the fisheries to collapse and close in those regions by 1997.
Charged with evaluating the progress of abalone population recovery, the California Department of Fish and Wildlife’s Invertebrate Management Project conducts research throughout the state, including sites within South La Jolla SMR. One method of evaluation uses baby abalone recruitment traps (BARTs), which consist of wire cage boxes filled with cinder blocks that act as pseudo-“habitat” to attract abalone. These BARTs allow scientists to determine how well abalone populations are recovering in a given area, such as inside and outside of MPAs, by gathering data from the traps to produce estimates of recruitment and population abundance.
Baby abalone recruitment monitoring within South La Jolla SMR began in 2011. So far, juvenile red and pinto abalone have been found in the BARTs, though not in significant numbers. Scientists hope that through continued monitoring of the BARTs, they will be able to track the progress of abalone recovery, particularly for the endangered white abalone. To date, no juvenile white abalone have been found in the BARTs, but the occasional adults have been seen in the surrounding area.
Besides abalone, scientists keep track of other species that occur in the BARTs, such as crabs, nudibranchs, chestnut cowrie snails, sea urchins, sea cucumbers, rock scallops, sea stars, and octopus. The species diversity and abundance information from this work will help to inform adaptive management decisions and guide the evaluations of South La Jolla SMR, which is critical for determining the overall success of the MPA.
California is home to seven species of abalone, and all of them can be found within South La Jolla SMR. As the largest SMR in San Diego County, and home to rocky areas suitable for abalone habitat, South La Jolla SMR could help reestablish the once abundant abalone populations of the Southern California coastline.
Learn more about MPAs by diving into the Exploring California’s Marine Protected Areas series!
post by Amanda Van Diggelen, CDFW Environmental Scientist