Center for Marine Biodiversity and Conservation

Over the past century, sea level has risen more than 20cm along the California coast, and it is projected that under medium-high emissions, mean sea level will rise by 1.4m over the coming century. The likelihood of losing current beach habitat due to sea-level rise constitutes a major threat for many wildlife species, such as pinnipeds that require terrestrial habitat for breeding, pupping, molting, and resting. This study applies GIS to analyze the impacts of sea-level rise on pinniped haul-out sites along the central and southern California coast. ArcMap was used to overlay inundation data with haul-out sites of three abundant California pinniped species: California sea lions (Zalophus californianus californianus), Pacific harbor seals (Phoca vitulina richardsi), and Northern elephant seals (Mirounga angustirostris). Affected area due to sea-level rise was also quantified for Northern elephant seal haul-out sites. GIS data showed that approximately 99% of haul-out sites among all species were affected throughout central and southern California. Furthermore, over 373,000m² of elephant seal habitat was found to be affected by sea level rise. These impacts may result in loss of pinniped habitat, redistrubtion of haul-out sites, and controversy over land use for humans or for pinnipeds. Given the potential for conflict, policymakers should begin to assess the Marine Mammal Protection Act and Coastal Act to ensure that these legislations will be able to meet management needs. Furthermore, adaption strategies such as structural protection may help alleviate pressure on pinniped habitat and prevent future controversy over land allocation.