The Dark Side of California Sea Otters


Sea otter mother with nursing pup.  Credit “Mike” Michael L. Baird.

For many years, I thought California sea otters were cute and cuddly. Who can resist watching them playing in the ocean, often with a baby otter alongside? Cute sea otter imagery is everywhere, from event logos to plush toys to bumper stickers, because we love them so much.

Sea otters also help keep the ocean healthy, in part because they are a keystone species in many locations. A keystone species plays a critical role in an ecosystem, out of proportion to their population. Without sea otters, underwater kelp forests can be gobbled down by sea urchins.

In September, the U.S. Fish and Wildlife Service announced the latest California sea otter population survey: “Slowly Swimming Towards Recovery.”

But this happy news reminded me of several sea otter stories which contrast with their cute and cuddly reputation.

Sea otters can be mean and nasty.


Did you know that you could catch serious diseases from sea otters? If you handle an otter or breathe the air close to a dead otter, you could catch bartonella (cat scratch disease), toxoplasmosis, brucellosis and coccidioidomycosis (valley fever). If you discover a sick or dead sea otter, stay away and contact the professionals at the Marine Mammal Center (415-289-7325), the Monterey Bay Aquarium (831-648-4840) or the California Department of Fish and Wildlife (831-212-7010).


People who handle live sea otters for a living must protect themselves from scratches and bites powerful enough to break bones. That’s not surprising, since sea otters are fierce carnivores, evolutionary cousins of badgers, ferrets, and wolverines. To most people these are not cute and cuddly creatures – except for superhero wolverines. Sea otter behavior is so bad that some people consider them sea wolverines.

Kidnap and ransom

Male sea otters will kidnap sea otter pups and hold them underwater until the female gives up her food. This happens often enough to get its own term: “hostage behavior.”

Bad mom

Sea otter moms will abandon pups to die of starvation if the mom isn’t healthy enough to raise the pup.

“You can see these females getting skinnier and skinnier,” as they raise their pups, said Nicole Thometz, of the University of California, Santa Cruz. So you really can’t blame the moms.

Sex and violence

Sea otter males pursue the females relentlessly during mating season. Even after they are caught, female sea otters vigorously resist mating. So vigorously, that the males hold the female’s head underwater to subdue her. Sometimes females drown during mating.

Because the male bites the female on the head to subdue her, females suffer serious wounds during mating – often biting the nose off of her face. In one survey, 4% of female sea otter deaths came from these wounds. And males will continue attempting to mate with dead females.

Sex and …

Scientists have observed some male sea otters pursuing, subduing, and attempting to mate with other species, such as harbor seal pups. Once again, these acts are sometimes so violent that the harbor seal pup dies – but the male sea otter keeps attacking the pup for up to seven days.

One sea otter attempted to mate with a dead bird and a dead dog. The otter was even suspected of killing the dog!


Sea urchins, clams and abalone never made it onto my list of cute and cuddly. But some people make a good living harvesting and selling these delicacies for our dinner plates. Wild abalone meat sells for $70 per pound, and sea urchin eggs used in sushi (uni) sell for $125 per pound.

That’s the problem. Sea otters really like shellfish – they will eat 10 to 25 pounds per day. The people that harvest shellfish see another dark side to sea otters – unfair competition, protected by the Endangered Species Act. One Alaska state senator proposed a $100 bounty on sea otters to protect shellfish harvesting. Luckily that proposal never went anywhere.

Mean and nasty

You could argue that we should not impose human values on sea otters. But we already call them cute and cuddly.

Don’t get me wrong – we need to protect sea otters.

But I hope you don’t mind if I call them mean and nasty, as well.

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One Response to The Dark Side of California Sea Otters

  1. Mike Baird 14 December, 2014 at 7:39 pm #

    Well written and full of new and intriguing facts.

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