Enhydra lutris nereis (Mammals)

Species Description

The Southern or California Sea Otter, Enhydra lutris nereis, is the smallest species of marine mammal in North America. Despite its relatively small size, the Southern Sea Otter is considered a “keystone” species in its ecosystem: the Pacfic Ocean’s kelp forest ecosystem. They do this by feeding on sea urchins. When the numbers of Sea Otters decline, increased sea urchin feeding leads to detachment of kelp, which in turn depletes the food supply for other marine animals.

Unlike other marine mammals that rely on a thick layer of blubber to stay warm in the cold waters of the Pacific, Sea Otters rely on their incredibly thick fur—with more hairs per inch than any other mammal in the world—to survive in the marine environment.

But this unique adaptation to life in the Pacific almost proved to be the species downfall. Fur traders prized Sea Otter pelts, and in the 1700s nearly clubbed and trapped the Sea Otter into extinction. There were between 150,000 and 300,000 Sea Otters living between Alaska and Baja California before this great hunt, but by 1900 it was thought that the species was extinct.

Fortunately a small remnant population was found off the Big Sur coast in the 1930s. The current population of these animals, roughly 3,000 in a recent survey, is drawn entirely from this tiny stock that was missed by the fur traders. The Southern Sea Otter was protected as a threatened species under the Endangered Species Act in 1977.

Sea Otters once were found along the entire Pacific coast of North America, including throughout San Francisco Bay. Today the species’ range is limited to coastal waters between the Santa Barbara Channel and Half Moon Bay. However, occasionally a rogue male will swim north passing through the GGNP’s waters and even enter San Francisco Bay. Nearly every year a Sea Otter is spotted from Inspiration Point or the Crissy Field Wildlife Protection Area, but the opportunities are quite rare.

Conservation Action Item

Reduce disease:
Landfill - never flush - kitty litter and/or ask others to do so

Although the hunt for sea otters has ended, many threats still impede sea otter recovery. Oil spills are a major concern, because once a Sea Otter’s fur is soiled it cannot retain heat and the animal will die. But most Sea Otter mortality today is caused by disease. One of the most disconcerting diseases has been the parasite Toxoplasma gondii. This microorganism isn’t naturally found in the ocean environment, but it is killing Sea Otters. Marine biologists have determined that the microorganism is getting into the ocean through cat feces — the T. gondii life cycle can only reach a stage hearty enough to survive the marine environment in cats, and when the organism is shed in cat feces it can wash away into the marine environment. This is why all cat litter sold in California must have a label warning people not to flush it down the toilet.

Help encourage Sea Otter recovery by always landfilling—never flushing—kitty litter. If you don’t have a cat, ask a cat owner you know to do the same.

For more information about this Conservation Action Item:

UC Davis Sea Otter Research

Big Year Competitors have reported 0 sightings and taken 0 actions to help this species recover so far this year.

Trips

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