2013-2016 California Sea Lion Unusual Mortality Event in California (CLOSED)
2013-2016 California Sea Lion Unusual Mortality Event in California (CLOSED)
Sea lion pups in rehabilitation. Credit: Pacific Marine Mammal Center
The Unusual Mortality Event involving juvenile California sea lions that began in January 2013 is over. The event was investigated by NOAA Fisheries and partners and was defined as occurring from January 1, 2013 to September 30, 2016 along the California coast. The majority of strandings occurred in Central and Southern California.
8,112 juvenile California sea lions stranded during the event, including 7,587 that stranded alive (~93%). The majority of strandings between 2013 and 2016 were early weaned California sea lion pups (6 to 9 months of age) and yearlings (1-2 years old) in poor body condition including severe emaciation. Based on necropsy, histopathology, diagnostic and environmental findings, the UME was attributed to malnutrition in juvenile sea lions due to ecological factors causing prey shifts. These prey shifts were most likely driven by unusual oceanographic conditions at the time due to the “Warm Water Blob” and El Niño.
California Sea Lion Data
Number of juvenile sea lions that stranded by year. The horizontal line is the mean number of Sea lions stranding from 2006-2012 (pre-UME) and the dotted lines are plus/minus one standard deviation. The years in which the UME occurred are in color.