Sea otters were hunted to near-extinction by the 1920s, leaving surviving populations small and vulnerable. They are now primarily threatened by oil spills, conflict with the fishing industry and diseases that are intensified by pollution. More than 40 percent of California sea otter deaths are caused by parasitic, fungal, or bacterial infections, and studies have linked these deaths to higher levels of toxins, including pesticides, in their marine habitat. Oil spills compromise sea otters' ability to insulate, causing them to die of hypothermia.
Why they're in trouble: