Southern sea otters are native to San Francisco Bay, and were plentiful here until they were hunted nearly out of existence more than a century ago. Because the sea otter is a "keystone species," occupying a spot near the top of the food chain, the health of the sea otter population is an important indicator of the overall health of the Bay Area ecosystem. Thanks to protective measures, California's otter population has slowly rebounded, but no otters have returned to the bay. Moreover, a recent dip in the statewide population is cause for concern.
NRDC researchers gathered data from the U.S. Fish and Wildlife Service on the numbers and general health of the southern sea otter population (the southern sea otter is one of three sea otter subspecies; it is found only off the California coast). The data indicate that the otter population has grown steadily, if very slowly, since 1920, after severe overhunting drove its numbers down to around 50. Just in the last few years, however, the population has dipped again and only 2,161 were counted in the Fish and Wildlife Service's spring 2001 survey. Biologists studying the animals attribute the recent decline to environmental contaminants, as well as to a parasite problem.
Over the last few decades, the sea otters have expanded their territory and now range roughly from Half Moon Bay to Santa Barbara, with a small population at San Nicholas in the Channel Islands. While occasional sightings have been reported near the Golden Gate in recent years, sea otters no longer make their home in the San Francisco Bay area.