Sea Otter Research and Conservation program


Counting California’s iconic sea otters

For the past 30 years, a team of scientists, volunteers and pilots has gathered to conduct an annual survey to answer one critical question: How many sea otters are there in California?

The census, led by the U.S. Geological Survey, is an opportunity to assess the progress of efforts to recover a population that was hunted to near extinction by fur traders.

Although hunting was banned more than a century ago and sea otters are today a protected species, the population continues to grow at a sluggish rate.

Federal listing in 1977 as a threatened species prompted the annual sea otter census along its entire range in California. Pups and adults are counted by teams on land, and a companion aerial survey helps calibrate the count (and potentially spot animals offshore, beyond sight of land-based census-takers).

A slow road back

Over the years, the population has advanced and declined. But one fact is clear: The southern sea otter population is not growing at a healthy rate. On average, 10% of the population is found dead each year. Annual mortalities include a growing number of sick, injured and stranded pups that are brought to the Monterey Bay Aquarium for care.

The 2012 census shows a slight increase in sea otters above 2010 count. (Poor weather conditions prevented a 2011 survey.) But the population is smaller than it was in 2007, when it reached the highest level recorded since the census began in 1982. Overall numbers remain well below the figure that would move sea otters off the endangered species list.

Scientists are concerned that mortalities include large numbers of breeding-age females, and the high rate of infectious disease across the population. Decades of intensive study show that the causes are complex. The solutions remain elusive.

So what’s a sea otter lover to do?

Actions that matter

In addition to supporting more research, and funding to pay for that research, sea otters need political assistance. The science indicates that there are problems with the health of our coastal waters, where these top predators live. Because sea otters eat many of the seafood items we enjoy, solving the threats they face can benefit our own health.

California taxpayers can support more research through a voluntary income tax check-off that’s already raised significant and much-needed funds. At the Monterey Bay Aquarium we’re playing our part, too. Through our rescue and rehabilitation work, we’re identifying the challenges sea otters face in the wild – through analysis of their diet, their vulnerability to boat strikes and their interaction with fisheries. Our exhibit sea otters serve as surrogates to raise stranded pups for return to the wild. We compare survival rates for surrogate-reared pups with wild-raised pups, and the health of otter populations in relatively pristine waters with those near populated coastal regions.

In Sacramento and Washington D.C., our policy team advocates for legislation to protect sea otter habitat, to allow otters to return to their original range – including waters off southern California – and to ensure there’s funding for research needed to recover the population.

We can do this vital work because of the support of our members, donors and visitors. Thank you for supporting sea otter health, the health of our coastal ecosystems and a future with healthy oceans.

(All photos ©Jim Capwell)

The High Cost of a Mother’s Love

How much energy does it take a mother sea otter to care for her pup? Quite a lot, it turns out. So much, that the effort of being a mom can put her own life at risk.

That’s the conclusion of a long-term research study just published by scientists from the University of California, Santa Cruz; and the Aquarium. It’s based on extensive observations of tagged sea otters in the wild, and others we rescued and raised through our Sea Otter Research and Conservation program.

It’s another vital piece of information about the lives of sea otters–data that’s critical to the recovery of California’s threatened sea otter population.

Learn more about the latest sea otter research.

Learn how you can support our sea otter work.

Help Us Find the Person Who Shot Three Sea Otters

In early September 2013, members of our Sea Otter Research and Conservation team recovered three sea otters that had been shot to death near Asilomar Beach, in Pacific Grove. State and federal authorities are actively investigating the fatal shootings, and now they need your help finding the perpetrator.

We and other sea otter conservation groups are offering a $21,000 reward for information leading to the arrest and conviction of the individual(s) responsible for the crime.

Southern sea otters are slowly recovering after being driven nearly to extinction by fur traders in the 19th century. Today, they’re protected under federal law by the Endangered Species Act and the Marine Mammal Protection Act. Killing a California (or southern) sea otter is a crime punishable by federal and state fines, and possible jail time.

If you have any information about the shootings, contact Special Agent Souphanya of the U.S. Fish and Wildlife Service at 650-876-9078. Anonymous reports can also be made by calling the U.S. Fish and Wildlife Service contact line at 703-358-1949, or the California Department of Fish and Wildlife CalTIP line at 1-888-DFG-CALTIP.

Reward contributions have been provided by the California Department of Fish and Wildlife, Defenders of Wildlife, Friends of the Sea Otter, the Humane Society of the United States, the Humane Society Wildlife Land Trust, the Monterey Bay Aquarium, The U.C. Davis Karen C. Drayer Wildlife Health Center and private individuals.

The California Department of Fish and Wildlife is providing a portion of the reward money from the California Sea Otter Fund, which is financed by voluntary contributions from state taxpayers. The fund helps support sea otter research and conservation, including the investigation of sea otter deaths and the enforcement of laws protecting sea otters. When filling out your California income tax form 540, look for line 410, labeled California Sea Otter Fund, under Contributions.

Learn more about the California Sea Otter Fund.

Good News For Sea Otters!

California’s sea otter population is a bit larger this year – good news for a threatened species that plays such a vital role in the health of coastal ecosystems.

Our sea otter research team joined university colleagues, and state and federal wildlife officials, in a spring otter count that tallied 2,941 animals from San Mateo County to the Santa Barbara/Ventura county line to the south.

The 2013 figure includes a record number of pups, which helped boost the three-year population average from the 2,792 average just a year ago. That is cause for “cautious optimism,” according to Tim Tinker, a sea otter biologist with the U.S. Geological Survey’s Western Ecological Research Center.

“Certainly, sea otters have made an impressive recovery in California since their rediscovery here in the 1930s,” Tinker says. “But as their numbers expand along California’s coast, they are facing ‘growing pains’ in different locales.”

‘Growing pains’

Those “growing pains” include everything from disease and parasites, to limits on available food, to a rise in the number of sea otters falling victim to shark bites.

For 30 years, the Aquarium’s sea otter research team has been a key player in collaborative efforts to understand why sea otters are recovering so slowly.

They’ve come a long way.

Presumed extinct in California after the fur trade years, a remnant population of some 50 animals was rediscovered in the 1930s with the opening of Highway 1 along the remote Big Sur coast. 

In addition to being a magnet for Central Coast visitors, sea otters are considered a keystone species in coastal ecosystems because they prey on invertebrates that, if left unchecked, can decimate kelp and seagrass beds and the vital fish habitat they provide.

Scientists also study sea otters as an indicator of nearshore ecosystem health, since sea otters feed and live near the coast and often are the first predators exposed to pollutants and pathogens that wash into the ocean from land.

Sea otter photo credit: ©Jim Capwell /

Good News for Sea Otter Conservation in Southern California

The Aquarium applauds this week’s decision by a federal judge to dismiss a lawsuit by fishing groups wanting to reinstate the controversial “no-otter” zone in waters off southern California.

The U.S. Fish and Wildlife Service established the “no-otter” zone in 1987 as part of a larger sea otter translocation program, but the program ended in 2012 after it was deemed a failure. In 2013, fishing groups sued the Fish and Wildlife Service for ending the program. A federal judge dismissed the lawsuit on Monday, but the fishing groups have 21 days to amend their lawsuit.

Under the translocation program, the Fish and Wildlife Service hoped to establish a colony of sea otters at San Nicolas Island off Santa Barbara and was required to relocate any sea otters found south of Point Conception. Wildlife officials determined that the “no-otter” zone prohibited sea otters from being able to naturally expand their range into areas and habitats where they had historically been present. Scientists believe such expansion is necessary for recovery of the southern sea otter, a threatened species.

Before they were hunted to the brink of extinction during the fur trade of the 18th and 19th centuries, it is estimated that more than 16,000 southern sea otters inhabited the west coast. Today’s population hovers below 3,000, and extends from just south of Half Moon Bay to south of Point Conception.

Sea otters play a critical role in ocean health, helping keep nearshore ecosystems in balance by eating sea urchins and other invertebrates that graze on giant kelp. If left unchecked, these grazing animals can destroy kelp forests and leave barren zones in their wake. Recent research from Elkhorn Slough has shown that an increased presence of sea otters directly contributes to recovery and expansion of eelgrass beds, which serve as nurseries for numerous species and as important filters of carbon and contaminants in estuary waters.

Learn more about our sea otter conservation efforts