Sea Otters at Risk

Sea otters are currently listed as a "threatened species" under the U.S. Endangered Species Act.

The southern sea otter is a threatened species

In 1750, thousands of sea otters lived and foraged along the California coast. Then fur hunters began killing them for their warm, luxurious pelts. By the early 1900s, only about 50 otters along the isolated Big Sur coast had escaped the slaughter. Today's southern sea otters are descendants of those few survivors.

With conservation efforts, the sea otter population has slowly grown to around 2,000, but that number has remained fairly stable for the past few years. Scientists are trying to determine the reasons for the recent lack of growth in the population. These recent growth trends and our lack of understanding about their causes mean an uncertain future for the California sea otter population.

Sea otter being cleaned of oil (� Tony Dawson)

Otters can be cleaned of oil, but the process is very stressful for the animals. After the 1989 Exxon Valdez spill in Alaska, 361 otters were brought to rescue centers and only 197 survived to be released (over 1,000 oiled otter carcasses were collected, and it's estimated that more than 2,000 otters were killed overall).

What threatens sea otters today?

The sea otter population in California remains small and vulnerable, and every otter counts. Parasites, such as intestinal worms, and infectious disease cause about 40 percent of otter deaths. Protozoal diseases are usually fatal to marine mammals, and they appear to be on the rise among wild sea otters, possibly because of higher pollution levels in coastal ocean waters.

The greatest threat to the otter population is an oil spill. Because their numbers are low and they are located in a rather small geographic area, the California otter population could be devastated by oil contamination. Oil ruins the insulating property of an otter's fur, so most oiled otters die of hypothermia. Prevention of oil spills is the best strategy, since rehabilitating oiled otters is quite difficult.

Why are sea otters important?

Otters have been called a keystone species. They contribute to the ecological balance of the ocean by eating sea urchins and other invertebrates that graze heavily on giant kelp. Too many of these grazing animals could destroy the kelp forest, home to many species of marine life.

Sea otters are also good indicators of the health of the ocean. Since otters are near the top of the marine food web, changes in their health can make scientists aware of variations in the ocean environment itself.

Inspiring conservation of the oceans