The feeding habits of the sea otter have a top-down effect on the marine ecosystem, meaning that their actions affect organisms lower in the food chain. Sea otters are also indicators of the health of that ecosystem. The sea otter derives much of its nutritional needs from shellfish which, unfortunately, put the otter at odds with the commercial shellfish industry. However sea otters play an important role in maintaining the health of the kelp ecosystem. By limiting the numbers of shellfish that feed on kelp, the sea otter promotes the development of kelp forests which are larger, more productive, and more diverse biologically and structurally.
Kelp beds, in turn, provide habitat for fish and other invertebrate species.
Because these sea otters lived so close to oil tanker traffic, a major goal of the recovery plan was to minimize risk from any potential oil spills. So, a plan was constructed to establish at least one additional breeding colony of otters outside the parent range. But the translocations were stopped when it became clear that sea otters were not remaining at San Nicolas Island at anywhere near the numbers expected. In fact, since 1990, there s always been fewer than 25 sea otters, even though 140 sea otters were moved to the island. This zone was located in the area off the California coast from Point Conception southward to the U.S.-Mexican border.