NOAA Fisheries researches the biology, behavior, and ecology of the California sea lion. We use the results to inform management decisions and recovery efforts for this depleted species.

Stock Assessments

Determining the number of California sea lions in each population—and whether a stock is growing or shrinking over time—helps resource managers assess the success of conservation measures. Our scientists collect information and present these data in annual stock assessment reports.

California sea lions on the move.

California sea lions on the move. Photo: NOAA Alaska Fisheries Science Center/Tony Orr.

Unusual Mortality Events

To understand the health of California sea lion populations, scientists study unusual mortality events. Marine mammal UMEs are important because they can serve as indicators of ocean health, giving insight into larger environmental issues that may also have implications for human health and welfare. Since 2013, more pups and yearlings have been stranded than usual in Southern California. Many are emaciated, dehydrated, and very underweight for their age. This event has been declared a UME.

Learn more about UMEs

Additional Research

NOAA scientists conduct wide-ranging research on the biology, life history, and health of California sea lions including:

  • Diet/foraging ecology.
  • Distribution and migration.
  • Threats such as disease, contaminants, and entanglement.
  • Genetics.

Learn more about what our scientists are working on