Sea otters are a keystone species, meaning their role in their environment has a greater effect than other species. As top predators, sea otters are critical to maintaining the balance of nearshore ecosystems, such as kelp forests, embayments and estuaries. Without sea otters, sea urchins can overpopulate the sea floor and devour the kelp forests that provide cover and food for many other marine animals. By maintaining healthy kelp forests, sea otters also indirectly help to reduce levels of atmospheric carbon dioxide, a prevalent greenhouse gas, as kelp absorbs and sequesters carbon. 

Hunted to near extinction in the 18th and 19th centuries, sea otters finally gained protections with the signing of the International Fur Seal Treaty of 1911. In the 1970s, they received additional safeguarding under the Marine Mammal Protection Act and the Endangered Species Act. Worldwide, sea otters have slowly recovered but still stand far below their historical population numbers. While sea otters are vulnerable to natural environmental changes, their populations are significantly impacted by several human factors as well.

Defenders' Impact
Sea Otter
Joshua Asel
  • In 2006, Defenders of Wildlife worked with California lawmakers on legislation that established the California Sea Otter Fund, a voluntary contribution option on the state tax forms. The fund pays for important scientific research, public education and law enforcement that benefits sea otters. 
  • Defenders helped pass a state law that mandated warning signs on containers of “flushable” kitty litter. This became necessary when researchers discovered that a protozoal parasite from flushed cat feces, Toxoplasma gondii, could pass through wastewater treatment facilities and harm sea otters.
  • We also worked to end to the translocation program, which moved sea otters to San Nicolas Island, and the associated No-Otter Zone.
  • We supported a bill to phase out the use of drift gillnets in California waters to protect sea otters and many other marine species.
  • To protect sea otters that were crossing roads in Moss Landing, CA, Defenders helped make the case for placing crossing signs and establishing slow speed zones, and we worked with local sea otter protection organizations to install wildlife monitoring cameras.
  • Finally, we are working with state and federal agencies and other groups to maintain, increase and broaden the current protections for sea otters so they can expand their population along more of California’s coastal waters. 

You can be a part of the solution for endangered species: support our efforts to protect the wild!

And join us every September for Sea Otter Awareness Week!


Humans are the biggest threat to sea otter populations. Direct conflict with humans, through shootings, fishing gear entanglements and boat strikes, take a toll on sea otters, but oil spills, pollution, disease and loss of kelp pose major threats.

Protection Status
Endangered Species Act
IUCN Red List
 Appendix I
What You Can Do

Watch sea otters from a safe distance and watching out for otters crossing roads. If you live in California, donate to the California Sea Otter Fund when you file your taxes. Help us protect sea otters!

Latin Name
Enhydra lutris
Southern sea otters weigh 45 to 65 pounds; northern sea otters can reach up to 100 pounds.
10 to 20 years

Sea otters live in shallow coastal waters in the northern Pacific. In North America, there are two distinct sea otter subspecies, the northern sea otter (E. l. kenyoni) and the southern sea otter (E. l. nereis). Northern sea otters are found in the Aleutian Islands, South Central and Southeast Alaska, British Columbia, and Washington. Southern sea otters, also called California sea otters, live in waters along the California coastline, ranging from San Mateo County in the north to Santa Barbara County in the south.


Historically, sea otters numbered between 150,000 and 300,000 animals throughout the Pacific Rim. The southern sea otter population, which once numbered about 16,000 animals, is hovering around 3,000 today.


Sea otters spend much of their lives in the water and can dive up to 330 feet when foraging for food, though most dives are much shallower. They often rest in coastal kelp forests, draping the kelp over their bodies to keep from drifting away.

Sea otters are one of the few mammals, other than primates, known to use tools. They use small rocks or other objects to pry shellfish from rocks and to hammer them open.


Mating Season: Throughout the year
Gestation: 6 to 8 months
Litter Size: Generally one pup, but sea otters can give birth to twins


Sea otters eat urchins, abalone, mussels, clams, crabs, snails and about 40 other marine species. Sea otters must eat approximately 25% of their weight in food each day to support their high metabolism.

Raft of Sea Otters Above a Kelp Bed
Lawrence Swayne

The Extraordinary Sea Otter

Tour the special places that play a part in the past, present and future recovery of California's sea otters!

Explore Sea Otters


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Celebrate 21 Years of Sea Otter Awareness Week

Defenders of Wildlife, Sea Otter Savvy, the Elakha Alliance, the Monterey Bay Aquarium and California State Parks will commemorate the 21st annual Sea Otter Awareness

Wildlife and Wild Places

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