When they were finally protected under the 1911 International Fur Seal Treaty, sea otters were thought to be extinct in California. The California sea otter population has since grown, albeit slowly, to about 2,000 and its range has inched toward the southern coast s shellfish-rich waters. Because sea otters lack the blubber that helps other marine mammals keep warm in the cold ocean water, they have to eat a lot. A single adult male, which weighs about 65 pounds, can go through 20 pounds of abalone, sea urchins, and other shellfish in just one day. Sea otters are such efficient predators that once they move into an area, they can strip it bare of large, accessible shellfish.
Biologists reply that southern California s shellfish levels are artificially high.
They argue that the only reason these coastal waters are so shellfish-rich is that the otters were wiped out there decades ago. Now that the otters are returning, the shellfish populations are merely dropping back to their historical levels. The conflict between California s sea otters and shellfishermen last came to a head during the early 1980s. At that time, the biggest threat to the otters was oil spills. Biologists thought the best bet for a new colony was San Nicolas Island, which lies 60 miles off Los Angeles.