By Mari Hansen A raft of otters was entangled in a strand of kelp like someone had knotted a rope and left, and fog was still hanging low over Moss Landing the morning I saw them. They were not being photographed. A man drinking coffee from the gas station gave the scene a single, unimpressed glance. More than any scientific report, that casual shrug reveals how bizarre this recovery has become. By the 1800s, sea otters had been hunted to extinction, and they are now only a minor feature along some parts of California’s coast. It’s worth stopping for just that.
The numbers are tiny and unyielding. There are still about 3,000 southern sea otters that fluctuate for years above and below the federal target of 3,090 without ever settling. A new census is anticipated soon, so it’s possible that the population is declining once more, but their ecological footprint is much greater than their headcount would indicate. Researchers from Duke’s Nicholas School discovered that returning otters have slowed erosion of the salt marshes in Elkhorn Slough, a muddy estuary that had been silently collapsing for decades, by stifling the crabs that were eating through the root systems. In other words, the reason the marsh is holding together is because a predator has returned.
| Category | Details |
|---|---|
| Species | Southern sea otter (Enhydra lutris nereis) |
| Current Population | Roughly 3,000 individuals (last full census: 2019) |
| Historic Range | Baja California to Alaska; today only about 13% occupied |
| Legal Status | Threatened under the U.S. Endangered Species Act since 1977 |
| Primary Habitat | Kelp forests, estuaries, and nearshore waters of central California |
| Diet | Sea urchins, crabs, mussels, clams — up to 25% of body weight daily |
| Key Threat | Shark bites, kelp loss, pollution, human disturbance |
| Lead Recovery Agency | U.S. Fish and Wildlife Service |
| Major Research Hub | Monterey Bay Aquarium surrogate-mother program |
| Ecosystem Role | Keystone predator; kelp forests store carbon, support fisheries |
People continue to be surprised by this recurring pattern. Urchins are consumed by otters. Kelp is consumed by urchins. Without otters, urchins transform kelp forests into “urchin barrens”—stony seascapes devoid of nearly everything—as described grimly by divers. The forest expands when the otter is allowed to return. According to Strong Coast, a conservation organization on the coast of British Columbia, lingcod populations have tripled and kelp has grown twentyfold in areas where otters have recolonized. Ecosystems seldom move in such clean multiples, so those numbers should be viewed with some skepticism, but the direction of travel is real.
The tension beneath all of this is less neat. Otters are relentless, hungry, and uninterested in quotas, so shellfish harvesters have legitimate worries. It seems reasonable that the West Coast Seafood Processors Association has requested that regulators proceed cautiously. Pretending that the trade-offs don’t exist is not a virtue. It is difficult to disagree with the long view, though. In addition to buffering storms and storing carbon, healthy kelp forests also support fisheries that commercial boats depend on. It’s the kind of math that only makes sense if you’re prepared to wait ten years to find the solution.
Everything is becoming more complicated due to climate change. White sharks have been driven further north by warmer waters, and their bites—which are typically investigative and infrequently consumed—remain a major cause of otter mortality. A marine heat wave known as “the Blob” killed off sunflower sea stars, causing purple urchins to burst, flattening the kelp and changing the otters’ diet. Their diets now include invasive green crabs and mussels. Watching this, biologists appear more interested than alarmed. The otters are making things up as they go. It’s still unclear if that’s resilience or a gradual loss of options.
There was something unsettling about the lack of ceremony when I watched a rescue team in Morro Bay earlier this year reunite an orphaned pup named Caterpillar with a female otter that it might or might not have belonged to—the Marine Mammal Center can’t always be certain. Not a single camera. There was no press release. It was just a boat, a small wet animal passed over a gunwale, and a Bluetooth speaker playing a recorded cry. The majority of California is not paying attention as the coast rebuilds itself, one ravenous, fur-covered mammal at a time. Perhaps that’s the idea.