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2015-2018 Guadalupe Fur Seal Unusual Mortality Event in California

Guadalupe fur seal undergoing rehabilitation.  Photo Credit: The Marine Mammal Center, NMFS Permit No. 18786-01.

Increased strandings of Guadalupe fur seals have occurred along the entire coast of California.  Guadalupe fur seals strandings began in January 2015 and were eight times higher than the historical average.  Strandings have continued since 2015 and have remained well above average through 2017.  Strandings are seasonal and generally peak in April through June of each year.

This event has been declared an Unusual Mortality Event (UME) and is occurring in the same areas as the ongoing 2015-2017 California sea lion UME.

Report a stranded fur seal or sea lion

The most important step members of the public can take to assist investigators is to immediately report strandings to the California Marine Mammal Stranding Network. Make the report by calling the West Coast Stranding Hotline at 866-767-6114

Report stranded fur seals or sea lions (or any marine mammal) to the local California stranding network.

Species Identification Tips

Species Color Size
Guadalupe fur seal thick, uniform dark brown to black fur males can reach 7 ft and 400 - 490 lbs; females 5 ft and 100-120 lbs
California sea lion juveniles and females are golden brown to blonde; adult males are dark brown to black males can reach 7.5 ft and 700 - 1000 lbs; females 6ft and 240 lbs



Post-release movements of two Guadalupe fur seals that were rehabilitated at The Marine Mammal Center in 2015.  “Ian” (red track, left) is a juvenile male fur seal and “Furbert” (green track, right) is a male pup fur seal that were released in June 2015 at Chimney Rock in Pt. Reyes National Seashore with satellite transmitters glued to their fur to track their movements and behavior. Furbert’s tag transmitted 71 days, until August 27, 2015 when the battery died. Ian’s tag stopped transmitting on August 11 after 64 days, perhaps because it was lost as a result of molting. The tracks are unfiltered, location estimates may be inaccurate with errors > 1500 m.

Why are Guadalupe fur seals stranding?

Guadalupe fur seal are stranding alive and dead and are mostly weaned pups and juveniles (1-2 years old).  Findings from the majority of stranded animals include malnutrition with secondary bacterial and parasitic infections.

All live stranded Guadalupe fur seals are being rescued by local marine mammal stranding network members and undergoing long-term rehabilitation at The Marine Mammal Center in Sausalito, California or SeaWorld in San Diego, California.

As part of the UME investigation process, an independent team of scientists (Investigative Team) is being assembled to coordinate with the Working Group on Marine Mammal Unusual Mortality Events to review the data collected, sample future Guadalupe fur seals that strand and determine the next steps for the investigation.

Guadalupe fur seal ready to be released. Photo Credit: The Marine Mammal Center, NMFS Permit No. 932-1905


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Updated: January 4, 2018