Northern Cousins
Photograph by Roy Toft, National Geographic Creative

The northern sea otter, shown here in Kodiak Island, Alaska, is doing better than the southern sea otter, says Harris. This is partly because the northern otters have more room to expand their populations.

All the islands and nooks and crannies along the Alaskan and British Columbian coastlines can house a lot more sea otters than California can, he explains. Southern sea otters off of California can expand only north or south along the coast.