“Unusual Mortality Event” for California Sea Lions

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NOAA Fisheries reports:


California Sea Lion
(Zalophus californianus)
Photo: NMFS National
Marine Mammal Laboratory

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.

Beginning in January 2013, elevated strandings of California sea lion pups have been observed in Southern California (Santa Barbara, Ventura, Los Angeles, Orange, and San Diego Counties). The area with the highest reported stranding rates is currently Los Angeles County, followed by Orange County, and strandings are increasing in San Diego County.

The increase of sea lion strandings continues and has intensified over the last few weeks. Live sea lion strandings are nearly three times higher than the historical average.

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. The California Marine Mammal Stranding Network continues to rescue and rehabilitate animals.

As part of the UME investigation process, an independent team of scientists (investigation team) is being 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 will focus on the immediate response and develop the investigative plan.


FAQs on the California Sea Lion UME in California

NOAA Fisheries has declared an Unusual Mortality Event due to significant numbers of California sea lion strandings (in five counties) beginning in January 2013.

Q: What is an Unusual Mortality Event?

A: An Unusual Mortality Event (UME) is defined under the Marine Mammal Protection Act as a stranding event that is unexpected, involves a significant die-off of any marine mammal population, and demands immediate response. There are seven criteria used to determine whether a mortality event is “unusual.” If the Working Group on Marine Mammal Unusual Mortality Events (Working Group), a group of marine mammal health experts, determines that an event meets one or more of the criteria, then an official Unusual Mortality Event is declared.

Q: What is the risk to humans?

A: Sea lions are wild animals and may bite people if approached closely. Because marine mammals and people can share diseases, the California Department of Public Health is urging the general public to stay away from marine mammals (either live or dead marine mammals) that are stranded on the beach. It is not clear at this time if there is any infectious disease risk to human health through contact with these animals.

Q: What criteria have been met?

A: The Working Group concluded that at least one of the seven criteria established for designation of a UME has been met. These mortalities are unusual because there is a marked increase in the magnitude or a marked change in the nature of morbidity, mortality or strandings when compared with prior records.

Q: How widespread is this Unusual Mortality Event?

A: Currently increased strandings of California sea lions have occurred in the following counties: Santa Barbara, Ventura, Los Angeles, Orange, and San Diego. However, the event may expand to northern counties over the following months.

Categories: California Sea Lion Deaths, Marine Mammal Rescue, nature

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