Sign up for


and other email updates

2013 California Sea Lion Unusual Mortality Event in California


Under the Marine Mammal Protection Act of 1972 (as amended), an Unusual Mortality Event (UME) has been declared for California sea lions in California from January 2013 through the present.

Elevated strandings of California sea lion pups have been observed in Southern California in the following counties:

Live California sea lion historical stranding rates for 2008-2012 (admits to rehabilitation facilities from Jan 1-May 31).
Data for 2013 is as of May 19, 2013.

Currently, the UME is confined to young of the year (born summer 2012) California sea lions. Consistent findings in the sea lions are emaciation and dehydration with most animals very underweight for their age. While intake rates have slowed in recent weeks, the California Marine Mammal Stranding Network continues to rescue and rehabilitate animals and has large numbers of animals still in care.

As part of the UME investigation process, an independent team of scientists (investigation team) has been assembled to coordinate with the Working Group on Marine Mammal Unusual Mortality Events (Working Group) to review the data collected and to determine potential next steps. The group has developed the investigative plan; as preliminary results are obtained, the composition of the investigative team may shift.


FAQs on investigation of the ongoing California sea lion UME are available.

More Information

Updated: May 30, 2013