Sea otters are a keystone species, meaning their role in their environment has a greater effect than other species.

As predators, sea otters are critical to maintaining the balance of the near-shore kelp ecosystems. Without sea otters, sea urchins would devour the kelp forests off the coast that provide cover and food for many other marine animals. As such, sea otters also indirectly help to reduce levels of atmospheric carbon dioxide, a prevalent greenhouse gas, as kelp forests play an important role in capturing carbon in coastal ecosystems.

Sea otters finally gained protections with the signing of the International Fur Seal Treaty of 1911 and became listed under the Marine Mammal Protection and Endangered Species Acts in the 1970s. Worldwide, numbers have slowly recovered but still stand far below original population numbers. While sea otters are vulnerable to natural predators, their populations are significantly impacted by several human factors as well.

Defenders' Impact

In 2006, Defenders of Wildlife worked with California lawmakers to pass legislation that would establish the California Sea Otter Fund for sea otter research through a voluntary tax donation check-off box on state tax forms. These funds are used to pay for important scientific research and public education benefiting sea otters.

Defenders was also responsible in passing a state law putting a sign on “flushable” kitty litter that warns against flushing kitty litter because researchers have found that Toxoplasma gondii from “flushable” kitty litter passed through many wastewater treatment facilities and, even in small amounts, harmed sea otters. We also worked to secure the end to the No-Otter Zone and the translocation program, as well as ban drift gillnets in California waters.

To protect sea otters that were crossing roads, Defenders made the case for crossing signs and slow speed zones and worked with local sea otter protection organizations to install wildlife cameras. Finally, we are working with state and federal agencies and other groups to maintain, increase and broaden the current protections for the sea otter so they can expand their population along more of California’s nearshore coastal waters. 


Humans are the biggest threat to sea otter populations. Direct conflict with humans, such as shootings and entrapment in fishing traps and nets pose a major threat to sea otters, but oil spills, other pollution, and loss of kelp forests are also threatening sea otters. 

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

Be sea otter savvy by viewing sea otters from a safe distance and watching out for otters crossing the road. If you live in California, donate to the California Sea Otter Fund when you file your taxes.

Latin Name
Enhydra lutris
California sea otters 45 - 65 pounds and Northern sea otters can reach up to 100 pounds.
10 - 20 years

Sea otters live in shallow coastal waters off the northern Pacific. In the U.S., there are two distinct sea otter subspecies, the Northern sea otter and the Southern sea otter. Northern sea otters are found in the Aleutian Islands, Southern Alaska, British Columbia, and Washington. Southern sea otters, also known as California sea otters, live in the waters along the California coastline and range from San Mateo County in the north to Santa Barbara County in the south.


Historically, sea otters numbered between several hundred thousand to more than a million. The southern sea otter population today is just over 3,000 in California.


Sea otters spend much of their lives in the water and can dive up to 330 feet when foraging for food. They sometimes rest in coastal kelp forests, often draping the kelp over their bodies to keep from drifting away.
Sea otters are also 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: 6-8 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 eat approximately 25% of their weight in food each day to support their high metabolism.

adopt a sea otter

Your adoption supports our work to educate people about the need to protect sea otters, continue our efforts to protect sea otters from the threat of oil spills, and help local communities and the fishing industry live in harmony with these animals.

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Washington, DC

Supreme Court Halts Effort to Reinstate Failed “No Otter Zone” in California

The U.S. Supreme Court today declined to review a Ninth Circuit decision that upheld the U.S. Fish and Wildlife’s termination of a failed experimental program known as the “No Otter Zone.” The U.S. Fish and Wildlife Service had determined the program would harm the California sea otter by excluding the animals from their historic range along the Southern California coast.