An immature stranded sea otter being examined
by CDFW scientists at the beach.
An illustration and photo depicting the specific external characteristics of sea otters.
The CDFW initiated sea otter population studies in 1968 in response to State Senate Concurrent Resolution 74. Mortality studies have been an important component to understanding the species population dynamics. A key objective in these mortality studies has been the diagnosis of causes of mortality and an assessment of the relative contribution of each cause to the total mortality Causes of sea otter mortality in California include disease, shark bite, other trauma, toxicosis, parasite infection, and others. For latest stranding results, see the USGS sea otter stranding page.
When responding to a dead stranded sea otter, biologists may collect the animal for a detailed examination at the MWVCRC, or may perform a beach necropsy. We assess the age, sex, decomposition level, nutritional condition, and many other internal and external characteristics. External characteristics that distinguish sea otters from other marine mammals include dark shaggy fur, paws on the forelimbs, and a tail that extends to or beyond the hind flippers.
Sea otter stranding response occurs through a network of collaborators. Biologists from the US Geological Survey, the Monterey Bay Aquarium, The Marine Mammal Center, the California Academy of Sciences, and other members of the California Marine Mammal Stranding Network all contribute to the collection of stranded sea otters in California. CDFW sea otter biologists also assist these partner agencies during stranding events involving other species including cetaceans, pinnipeds, seabirds, and sea turtles. The Monterey Bay Aquarium sea otter program also is the primary response organization for live stranded sea otters.
To report a stranded sea otter or oiled wildlife:
Live Sea Otters in distress
- Northern Santa Cruz Co. and north: The Marine Mammal Center (415) 289-7325
- Monterey Bay area: Monterey Bay Aquarium Security Office (831) 648-4840
- San Luis Obispo Co and south: The Marine Mammal Center (805) 771-8300
Dead sea otters
- Santa Cruz Co. and north: CDFW, Colleen Young (831) 687-8776
- Monterey Co.: Monterey Bay Aquarium Security Office (831) 648-4840
- San Luis Obispo Co. and south: CDFW, Mike Harris (805) 772-1135
- Statewide: Oiled Wildlife Care Network: 1 (877) 823-6926