California released 37 orphaned sea otters into a bay scientists had already written off as dead — a desperate experiment that few believed could work. For fifteen years, the marine ecosystem showed no obvious signs of recovery, and experts quietly assumed the otters had vanished.

In 2001, biologists in California took 37 orphaned sea otter pups that had been found sick or stranded along the coast and released them into Elkhorn Slough, an estuary about 20 miles north of Monterey Bay. At the time, the site was in poor condition: more than half of its marshland had eroded since the 1950s, algae blooms were choking the eelgrass, and burrowing shore crabs were destabilizing the…

California put 37 orphaned sea otters into a supposedly dead bay, hoping they might somehow survive. For fifteen years, the experiment seemed to vanish without a trace.

In 2002, the Monterey Bay Aquarium released an orphaned sea otter pup into Elkhorn Slough, a degraded California estuary north of Monterey Bay. The pup had been raised by a non-releasable female otter named Toola, who had adopted it inside the aquarium’s exhibit tank. Over the next 14 years, 36 more orphaned pups followed the same path. Stranded on California beaches, rescued within days of birth,…