Recovery of Sea Otters in the North Pacific
Sea otters in the North Pacific were hunted to commercial extinction by the year 1900. After sea otters (and fur seals) were protected by international treaty in 1911, their populations started to recover and return to shorelines they formerly inhabited. Sea otters are called keystone predators because they exert a disproportionally large effect on the ecosystem. If sea otters are present on a rocky coast, there will be kelp beds and a variety of other animals using the habitat; if sea otters are not there to keep down the sea urchins, the kelp beds are eaten away and the habitat is greatly simplified and overrun with sea urchins.
In a related development, sea lion populations in the North Pacific have decreased substantially during the last twenty years, probably because of overfishing by people. Orcas, also called killer whales, used to prey on the sea lions of the Bering Sea but now that sea lions are scarce, they have switched to hunting sea otters, and sea otters are once again missing from large parts of their range.
We spoke with Professor James Estes about sea otters as keystone predators, their overall recovery and recent setbacks in the Aleutian Islands.