On a blue-sky afternoon, kayakers paddle past dozens of sea lions lolling in the sun and make a beeline toward the sea otters lounging on beds of eel grass at Elkhorn Slough on California’s central coast. The playful predators not only generate millions of dollars in tourism revenue, but their voracious appetite for destructive species has revived this sprawling estuary while making the region’s carbon-sequestering kelp forests more resistant to climate change.

The U.S. government determined in 2022 that reintroducing sea otters to their historic range on the West Coast would be a boon to biodiversity and climate resilience, laying out a road map to restoration that would cost up to $43 million.

But as the Trump administration moves to slash funding for wildlife programs, a nonprofit co-founded by a Silicon Valley entrepreneur is stepping in to raise nearly that amount to finance and coordinate what would be a complicated, years-long effort to connect isolated populations of sea otters. So far it’s raised more than $1.4 million of its $40-million target.

“We are coming in at a time when we’ve seen these dramatic cuts from the federal government and conservationists are facing major funding gaps,” says Paul Thomson, chief programs officer at the Wildlife Conservation Network, the San Francisco nonprofit that launched the Sea Otter Fund earlier this year. In August, a veteran U.S. Fish and Wildlife Service official, Jen Miller, left the government to run the fund.

Sea otters prey on invasive green crabs, which fostered the return of eel grass at Elkhorn Slough.

(Rachel Bujalski/Bloomberg)

The initiative could be a harbinger of a future where private donors assume a more prominent role in financing and advancing wildlife restoration as climate impacts multiply.

While philanthropies have helped fund sea otter work, the Fish and Wildlife Service, which listed the Southern sea otter in California as threatened in 1977, assumes the cost of the species’ recovery as well as funding state and private research. “Sea otter recovery and supporting healthy coastlines go hand in hand, including finding ways to support the needs of our local fisheries,” a Wildlife Service spokesperson said in a statement, noting the agency has funded ongoing research.

Future support is uncertain, though, as the Trump administration proposes eliminating programs that underwrite sea otter science, including grants for state endangered species programs.

Understanding otter networks

Sea otters once inhabited the Pacific Rim from Japan to Mexico. By the turn of the 20th century, hunters had wiped out 99% of the population to satisfy demand for the animal’s pelt, known as “soft gold” for its luxurious warmth.

Since then, scientists successfully reintroduced otters to Alaska, British Columbia and Washington State, but that leaves a nearly thousand-mile stretch of coast from central California through Oregon without the animals.

“Adding sea otters completely changes the configuration of the food web and that has profound consequences for the structure of the nearshore ecosystem,” says Tim Tinker, an independent sea otter scientist who does research for the University of California at Santa Cruz.

He’s developing computer models to simulate the myriad factors that will determine where and which animals should be reintroduced, as well as risks and survival rates. Future versions of the model could also project the potential impact on fisheries.

The Sea Otter Fund is financing Tinker’s work, recruiting him to model restoration scenarios, the kind of research he previously has conducted with government funding. It’s the latest animal fund from the Wildlife Conservation Network, co-founded in 2002 by former software entrepreneur Charles Knowles. Ongoing campaigns fund the recovery of African elephants, lions, pangolins and other animals.

Michelle Staedler studies sea otters at Elkhorn Slough.

(Rachel Bujalski/Bloomberg)

The fund also underwrites marine biologist Michelle Staedler’s position on an Elkhorn Slough research team run out of UC Santa Cruz. “We’re really trying to understand the sea otters’ social networks,” she says.

Charting otters’ social graph is key to future restoration efforts. Past reintroductions have involved capturing random sea otters in the wild and relocating up to hundreds at a time, which resulted in high mortality of resettled animals. Of the 140 otters relocated off Southern California’s San Nicolas Island between 1987 and 1990 in a federally funded project, only about 15 animals initially survived. More than a quarter of the transported otters swam more than 150 miles back home.

Scientists say any future reintroductions will be highly targeted, selecting sea otters that are part of social groups whose bonds make them more likely to stay put and thrive. To lay that groundwork, Staedler spends a day on Elkhorn Slough twice a week, motoring through the estuary on an electric skiff to record the genders, locations, relationships, interactions, diets and caloric intake of tagged otters.

“Elkhorn Slough serves as a petri dish and the research work there will be critical for doing restoration,” says Knowles. State funding for that project has expired, however, and the Sea Otter Fund is considering replacing the loss.

Staedler keeps records of the sea otters on Elkhorn Slough.

(Rachel Bujalski/Bloomberg)

“This wave has been building”

Elkhorn Slough is California’s second-largest estuary, and the 7-mile-long outlet to Monterey Bay also serves as a real-time laboratory for how sea otters can rehabilitate degraded coastal ecosystems and benefit local economies.

In the early 1990s, invasive green crabs that made their way there destroyed eel grass meadows that serve as habitats for fish, shellfish, sea turtles and birds. Then a few sea otters began to venture in just as the Monterey Bay Aquarium began to release rehabilitated orphaned otters there. They feasted on the green crabs, consuming an estimated 120,000 of them a year, according to a 2024 paper.

As crab numbers plummeted, the eel grass returned and spawned an aquatic Serengeti. Today, there’s more than 120 sea otters at the estuary, which has fostered local ecotourism businesses that rent kayaks to visitors and take them on otter-spotting excursions, generating $5 million in revenues annually and creating more than 300 jobs, according to a 2023 study.

Kayakers approach a sea otter in Elkhorn Slough.

(Rachel Bujalski/Bloomberg)

Sea otters also have kept kelp-eating purple urchins in check on the central California coast when one of its other predators, the sunflower sea star, died off during a marine heat wave a decade ago. On California’s otter-less North Coast, the loss of sunflower sea stars wiped out more than 90% of the region’s kelp forests, triggering the collapse of fisheries.

But the competition that relocated otters’ prodigious appetites could pose to Northern California and Oregon commercial shellfish fishers worries Lori Steele, executive director of the West Coast Seafood Processors Assn. “It’s very difficult to really fully understand and account for the potential damage to a shellfish population that a very small number of sea otters could do,” she says.

The Wildlife Service found that impacts on fishing communities pose the biggest risk of sea otter introduction. If relocation moves forward, the agency will conduct an extensive review and consultations with state and federal agencies and tribal groups.

Until then, Jen Miller, the senior manager of the Sea Otter Fund, aims to keep the money for the work flowing. “It feels like this wave has been building and building and with just the right resources could crest to surf sea otter restoration to success,” she says.

Woody writes for Bloomberg.