California Sea Otter Population Declining

Life’s never easy for California’s sea otters. Even in the best of times, they scrape by on just enough food in water that’s just warm enough with fur that’s just thick enough to allow them to survive without a layer of blubber (insulating fat).

Now scientists say their numbers are falling for new reasons that aren’t fully understood:

“This year was an alarming number of white shark attacks that we identified,” says Dr. Michael Murray, a Monterey Bay Aquarium veterinarian. “I think the jury’s still out on, ‘a’ what it means and ‘b’ why it happens.”

It’s puzzling because the sharks don’t eat the otters, but one bite is enough to kill the furry creatures. It’s one reason for a worrying decline in the number of California sea otters.

The latest count of this threatened species shows their population dropped to just 2,711, a decline of 3.6 percent. The number of sea otter pups, which represent the future of the species, is down 11 percent.

But sharks are only part of the problem. Otters are also dying of heart failure:

Heart disease could be linked to the otter’s voracious appetite that makes it vulnerable to toxic runoff from land, says Tim Tinker of the U.S. Geological Survey, who tracks the otters’ food supply.

“Disease causing parasites are going to end up in the ocean there. And sea otters are at the top of the food chain,” Tinker said.

Pollution is only the most recent threat to sea otters posed by humans. They were hunted to near-extinction by the early 20th century before an international ban on hunting, conservation efforts, and reintroduction programs allowed sea otters to rebound.

Learn more about sea otters at NWF’s Ranger Rick.