The Effect of Sea Otter Re-establishment in Southern California on the Remnant Populations and Recovery of Black Abalone, An Endangered Species

The black abalone is a long-lived intertidal marine snail listed as endangered under the federal Endangered Species Act. The southern sea otter is a voracious marine mammal that adores abalone, is also federally protected and, with the termination of the “otter-free” management zone, is now allowed to expand its range naturally into Southern California. Broadly, this project seeks to evaluate the potential impact of the otter’s free-ranging status on black abalone populations at the four northern Channel Islands (Anacapa, Santa Cruz, Santa Rosa and San Miguel). These offshore islands are within the otter’s new foraging territory and are believed to be home to more than half of all abalone in Southern California. In the project’s first year, biologists will begin conducting field surveys to map the locations and sizes of black abalone, as well as the numbers of animals residing within deep, rocky crevices beyond arms reach of otters. The quality of black abalone habitat will also be evaluated and mapped. In the project’s final stages, researchers will assess the proportion and location of abalone populations vulnerable to otter predation. Results will be rendered into GIS-compatible formats essential to developing mitigation and management strategies for two recovering, protected species.