USGS Western Ecological Research Center

Home Who We Are Where We Are What We Do Products Search Outreach Jobs Contacts

The California Sea Otter Stranding Network is part of the USGS effort to monitor southern sea otters (Enhydra lutris nereis) and provide data to the U.S. Fish and Wildlife Service.


The number of sea otter strandings in 2014 (386) was the highest on record, 18 above the 368 sea otters that stranded in 2012.  There were 340 strandings in 2013 (see spreadsheet tables 1-3).

A stranded sea otter is one that washes ashore dead or alive. Most live sea otters that strand either die or are euthanized shortly thereafter. Some get treatment and survive through rehabilitation (but would have died without treatment). The vast majority, however, are dead when they strand.

Again this year the high number of strandings observed can be partly attributed to more sea otters being bitten by white sharks, a cause of death that has been increasing over the last decade. An increase in shark bitten otters accounts for, in part, the record stranding totals in September  and October (44% and 48% of all strandings were shark bitten, respectively), as well as the elevated stranding numbers in March and August (spreadsheet Table 3). A high proportion of stranded animals were again found with shark bite wounds along the shores of Estero Bay and Pismo Beach in 2014, as well as the northern region of Monterey Bay (spreadsheet Table 1).

Stranding locations and field age composition of the stranded animals in 2014 were very similar to that seen in 2013.   Considerably more males than females stranded in 2014 (spreadsheet Table 2).

Efforts are made to recover and examine each reported sea otter carcass, and a subset of fresh carcasses are sent to the CDFW OSPR Marine Wildlife Veterinary Care and Research Center, where veterinarians conduct necropsies to determine the primary causes of death and identify factors that may have contributed to the death of each animal. Final determinations on cause of death are made after laboratory results are received, and the final records are provided by the CDFW OSPR Marine Wildlife Veterinary Care and Research Center.

NOTE: Stranding numbers only account for sea otters that people find, including any dead animal, or stranded live animal that would have died without intervention. Past research indicates that possibly less than 50% of sea otters that die in the wild end up on the beach, so the data presented here at best provide only an index of trends in population mortality.

Updated 2014.07.23

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo logo U.S. Department of the Interior | U.S. Geological Survey
Page Contact Information:

References to non-U.S. Department of Interior (DOI) products do not constitute an endorsement by the DOI.

* DOI and USGS link policies apply.