Davis, California - The U.S. Geological Survey says central California sea otters risk higher exposure to disease-causing parasites due to the food they eat and where they feed.

Researchers said sea otters that eat small marine snails are at a higher risk of exposure to Toxoplasma gondii, a potentially deadly protozoal pathogen, than animals that feed exclusively on other prey. Sea otters living along the coast near San Simeon and Cambria are more at risk than sea otters outside that area.

"Recovery of the sea otter in California has been especially sluggish at the center portion of its range, where sea otter densities are highest and where most of the reproduction occurs," said Tim Tinker, co-leader of the study led by the USGS and the University of California-Davis. "Where food resources are limited, individual sea otters tend to become diet specialists, and the specific skills used to secure food are passed on from mother to pup."

The study's co-lead author, UC-Davis epidemiologist Christine Johnson, added: "Our findings indicate that prey choice in sea otters has very real implications for their health. Depleted resources and high rates of infectious disease may be acting in concert to limit the recovery of this threatened species."

The findings appear in the Proceedings of the National Academy of Sciences.