The Great Sea Otter Comeback Is Reviving the Pacific’s Kelp Forests

A little over a century ago, the sea otter had been hunted so relentlessly for its luxurious fur that perhaps only around 2,000 of the animals survived across the entire North Pacific. The species seemed destined to vanish. Instead, it has staged one of the most heartening recoveries in marine conservation: today nearly 100,000 northern sea otters ply U.S. waters, with roughly 95,000 of them in Alaska alone.

The otters’ return matters for far more than their own sake. Sea otters are a classic “keystone” species, an animal whose presence shapes an entire ecosystem. Their favorite food is the sea urchin, and where otters are abundant, urchin numbers stay in check. That balance is crucial because, left unchecked, urchins mow down kelp forests, turning lush underwater jungles into barren rock. Researchers partly attribute the loss of more than 90 percent of Northern California’s kelp forests roughly a decade ago to the absence of otters in those waters.

Where sea otters have reestablished themselves, the picture is brighter. Studies have found that otter density is the single strongest predictor of kelp canopy cover across the Pacific Coast, and that otter populations have acted as a powerful buffer against widespread kelp loss. Healthy kelp forests, in turn, shelter fish, invertebrates and countless other species, store carbon and protect shorelines — meaning the otters’ recovery sends benefits rippling through the whole coastal ecosystem.

Conservationists are clear-eyed about the work still ahead. Southern sea otters number only around 3,000, just shy of recovery targets, and reintroductions must be done thoughtfully to balance the needs of wildlife with those of coastal communities and fisheries. But the broad arc is unmistakable: an animal that once teetered on the edge of extinction is now thriving and, in the process, helping to heal the underwater forests it calls home. As one analysis put it, done right, sea otter recovery serves not only the species but also the people who live and work along the coast.