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)


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About me

The Monterey Bay Aquarium, perched on the edge of a world-famous coastline, is your window to the wonders of the ocean. It’s located on historic Cannery Row in Monterey and is open daily except Christmas Day.

For more information about our animals and exhibits, and to view our live web cams, please visit

Hours of operation vary by season. Daily schedules and tickets are available on our website or by calling
(831) 648-4800.