The luxurious waterproof coat that insulates sea otters from the chilly waters they inhabit almost led to their extinction. A target of the commercial fur trade, the species was almost wiped out, its population reduced from an estimated 300,000 in the early 1700s to some 2,000 by 1911. That year an international ban on commercial hunting was enacted. That ban and management and conservation measures taken in the wake of the 1972 Marine Mammal Protection Act have helped populations recover to perhaps 128,000 worldwide by the early 21st century. Still, sea otters are highly vulnerable to both natural phenomena such as killer whale predation and to anthropogenic factors such as oil spills.
