Supplementary article not published in the printed edition of The Scientist.
Sea otters once cavorted all along the rim of the Northern Pacific, from Japan across the Arctic and down to Baja California, and their total population was estimated as high as 300,000. Today, only small populations of sea otters remain along the Pacific shorelines from central California to Alaska, and along the coasts of Russia.
A member of the weasel family (Mustelidae), the sea otter (Enhydra lutris) averages about 3.5 feet in length (its tail extends as long as a foot) and weighs about 70-80 pounds. There are actually three subspecies of sea otter. In addition to the California sea otter (Enhydra lutris nereis), also known as the Southern sea otter, there are two other subspecies: Russian (Enhydra lutris lutris) and Alaskan (Enhydra lutris kenyoni).
Sea otters spend most...