December 16, 2011

Reef Check Spotlight: Sea Otters Sighted in Southern California (Again!)


By Reef Check California’s Southern California Manager, Colleen Wisniewski

If you had been standing on the shore at Catalina Island or Laguna Beach in the early 1700s, you might have witnessed sea otters swimming in the kelp. However, otters were hunted to near extinction. Today, we expect to see Southern sea otters (Enhydra lutris nereis) from San Mateo County in Central California to just below Point Conception, although their historical range is from Oregon to Baja. The current number of otters is estimated to be approximately 2,700, which is considerably less than their past population. The Southern sea otter has had quite a fascinating history here in Southern California.

Southern sea otters are typically considered keystone species of kelp forests, meaning that they have a specialized and central role in the way an ecosystem functions. In the case of a kelp forest, sea otters can help control populations of herbivorous urchins. Without otters to prey on them, the number of sea urchins in a kelp forest can explode. Large numbers of urchins can consume a lot of kelp, creating urchin barrens, or areas completely denuded of kelp. Here in Southern California, predators such as lobsters and large fish can also help control urchin populations; which is good news since the Southern sea otters have been missing from Southern California for many years.

Unlike most of their marine mammal counterparts, sea otters don’t have blubber to insulate them. Instead, otters rely on very dense fur – estimated at over 1 million hairs per square inch – to help them thermoregulate. Because of this lack of insulation, otters have a very high metabolism and they must consume approximately 25% of their body weight in food a day. Their diet includes crabs, clams, snails, sea cucumbers and other bottom dwelling invertebrates, including urchins. Since their fur is much more dense compared to other animals, they gained a reputation for their luxurious pelts. During the 18th and 19th centuries so many otters were hunted for their pelts that by the early 1900’s, they were nearly extinct. The only Southern sea otters that were found along the coast at that time was a very small population near Big Sur. This was drastically reduced from their population before the hunting began. Remaining otters were protected in 1911 by the International Fur Seal Treaty and then again in 1977, when they were listed as threatened under the Endangered Species Act.

\"\"In 1987, the Fish and Wildlife Service embarked on a Southern sea otter translocation program and its main goal was to improve otter recovery. This was a two pronged approach. The first part was the creation of a “translocation zone,” into which sea otters would be moved. 140 Southern sea otters were moved to San Nicolas Island in an attempt to create a colony outside of their range, thus maintaining a population in case of an ecological disaster along the mainland coast, such as a large oil spill. The second part of this project was the designation of a “no-otter” management zone, which would be maintained as otter-free because of fishermen’s concerns. This area included all California waters south of Point Conception except the area surrounding San Nicolas Island. These otters still faced some challenges, with a number of otter deaths attributed to entrapment in fishing gear, loss of habitat and exposure to disease and contaminants from human activities on land.

There has been some buzz in the news regarding the Southern sea otters during the last few months. First, the Fish and Wildlife Service announced in a press release in August 2011 that they are proposing “to end the 24-year-old southern sea otter translocation program in California following an in-depth evaluation that found the program is not meeting its objectives for restoring the species.” This change in regulations would stop the translocation of otters to San Nicolas Island (the current small population would be left there) and also effectively end the management of the “otter-free” zone south of Point Conception. This would allow for the natural expansion of sea otters in Southern California. This policy modification has the potential to be a controversial issue as it could have an effect on commercial shellfish fisheries, and as such, a series of public hearings was held in October. In other news, during an October 2011 boat tour with a group of bird-watchers, a single sea otter was observed in the kelp forest canopy just outside San Diego Bay. And most recently, in early December 2011, a group of whale watchers off the coast of Laguna Beach spotted a solo male sea otter.

Sea otters have had an intriguing history along the Southern California coast over the last 200-300 years. It will be interesting to see if we notice any shifts in their current ranges within our lifetimes, especially with the new changes in management practices that will be taking place over the next few years. Soon it may not be too far-fetched to see otters from the shore of Catalina Island after all!