Sea otter pups are adorable. But they aren’t wanted everywhere.

MONTEREY BAY, CALIF. - The two-and-a-half-week-old sea otter cried for help. Stranded in a tide pool after heavy winds and strong surf near the edge of the bay, it was ashore and alone.

When Sandrine Hazan arrived, she scruffed the 4-pound 10-ounce fuzzball by the nape of its neck. A stranding and rehabilitation manager at the Monterey Bay Aquarium, she knew this was the last chance to find this pup’s missing mom.

Hazan climbed high on the windblown beach and held the female pup up, allowing its meek calls to project over the clamoring waves. Maybe, she hoped, the mother otter would hear its baby and reveal itself - if it were still out there.

“We do always put the effort in to look for mom,” she said. Finding mom is “really what’s in the best interest for the pup.”

The young otter wailed and wailed but to no avail. Its mother never returned.

That’s when Hazan did the next best thing - and took in the pup, in the hopes of rehabilitating it while preserving its wildness.

In an age of mass extinction, people are going to enormous lengths to put species back into place. They are flying baby wolves over mountains, shipping sharks across oceans and airlifting flightless birds between islands — all in an effort to repopulate portions of the planet humans have stripped of native animal inhabitants.

The U.S. government is now floating the idea of repopulating a wide swath of the Northern California and Oregon coastline with otters after they were hunted out of existence there more than a century ago. Reintroducing otters would not only boost the population of a beloved marine mammal. It may also restore entire ocean ecosystems, ones that are essential in the fight against climate change.

The extinction crisis, with a million species at risk of vanishing, means people have to get good at finding new habitats for animals. But rewilding efforts are expensive, time-consuming and difficult, requiring intimate knowledge of a creature’s needs. The programs often come with plenty of opponents and no guarantee of success.

The challenge of living among reintroduced otters was on display after a surfboard-stealing otter became a viral sensation this summer. Though the furry thief was beloved online, scientists see an animal dangerously habituated to humans.

Hazan knew the orphaned otter, eventually dubbed Otter 936, belonged in the bay. But it would be a long journey back into the wilderness - for this pup, and for its entire species.

A new home

Sea otters are born survivors. Nearly wiped out by fur hunters in the 18th and 19th centuries, California’s population would have been gone for good had a raft of a few dozen not eluded the slaughter off the rocky coast of Big Sur.

When it took in its first pup in 1981, the aquarium was still under construction. The youngster split time between an inflatable kiddie pool and an employee’s home bathtub. That pup ultimately died.

Since then, the aquarium has honed its approach, making sure otters remain untamed.

For about a month, Hazan and her team bottle-fed Otter 936. Stepping in for its lost mother, she rubbed down its fur with towels, unmatting its thick coat.

But before entering the otter’s enclosure, Hazan donned a tinted face shield, a black poncho and a pair of Kevlar gloves - an amorphous outfit meant to obscure the human form and ensure the youngster did not associate people with food. Unofficially, staff call it the Darth Vader suit.

On a recent morning, Hazan, dressed like Vader, placed pieces of meat on a floating pup’s belly. The otter lifted its head, awkwardly maneuvering its stubby arms to bring the morsel to its mouth.

Hazan and other staffers mostly stayed out of sight, watching the otter via video monitors one room over. On a laminated sheet of paper was a checklist of developmental goals: manipulating toys with its paws, fetching objects from the bottom of the tank, picking up solid food from a shell.

Hazan has worked at the aquarium for 15 years. She got into this business, she admitted, because she “wanted to play with animals.” The more she rehabilitated otters, the less she noticed how adorable they are.

“If you’re dealing with critical-care animals, that’s what you’re looking at,” she said. “You’re looking at an animal that needs your help. You’re not looking at a fuzzy, charismatic, adorable animal. Your mind-set changes.”

An otter comeback

Over the past four decades, Monterey Bay Aquarium has rescued, raised and released hundreds of pups back into the Pacific. The otters have already transformed ecosystems.

Nowhere is that more obvious than in Elkhorn Slough. Since being restocked in the 1990s with otters, eelgrass in the tidal estuary about 20 miles up the coast from the aquarium has flourished because of a remarkable ecological cascade.

Otters feast on crabs, keeping their numbers in check. That, in turn, allows snails, which the crabs like to consume, to prosper. And the snails eat algae that would otherwise block sunlight from reaching the seagrass.

The unexpected result: The introduction of otters in Elkhorn Slough helped boost eelgrass by 60 percent, according to a 2013 study, turning it into a vibrant nursery of juvenile fish and a crucial pit stop for migratory birds.

“A top predator like the sea otter can shape an ecosystem,” said Monique Fountain, a project director at the Elkhorn Slough National Estuarine Research Reserve.

To teach rescued pups what it takes to make it in the wild, Hazan pairs each baby with one of the aquarium’s adult female otters.

Otter 936′s surrogate, Selka, demonstrated how to dive, fetching food at the bottom of the tank and lining up the morsels on a platform. Unlike the wild-captured pups, the aquarium’s resident otters get names.

The ambition now is to recruit otters to help restore the ecological health of a much wider swath of the West Coast. Over the past decade, kelp forests off Northern California and Oregon have collapsed. After a mysterious disease wiped out the predatory sunflower sea star, rapacious urchins have flourished, felling the massive underwater forests.

Reintroducing otters would bring back a natural predator that could keep the urchins in check. Kelp not only provides hundreds of sea species with shelter; it also holds the potential to lock climate-warming carbon deep in the ocean, out of the atmosphere.

‘You have to challenge them’

Stepping around weathered beach rocks, Hazan was out at low tide early one June morning to hunt for urchins. Squatting at the edge of a tide pool, she plucked handfuls of the glistening purple invertebrates out of the rock.

Some otters, she explained while plopping urchins into a metal bucket, will just bite right into the tough, barbed bodies. “Others will try to use a tool.”

Back at the aquarium, she stocked an empty tank with the bounty from the beach, which in addition to the urchins included some 300 mussels and a thick strand of feathered kelp several times her length.

But she didn’t want to offer a free lunch. Wading into the tank, she tucked the mussels and other food morsels between piles of rocks in the enclosure so the prey could cling on - just like it does in the wild.

Hazan said she takes “a tough-love approach.” She has to. The open ocean is far less forgiving than the aquarium.

“We are always trying to think of how we can prepare them to be successfully released,” she said. “And if you’re handling them with kid gloves, both physically and mentally, that’s not the best outcome.”

“You have to challenge them.”

Employees used to hop right in the water with otters, teaching them to dive and even sleeping alongside them. But an aquarium-led study later revealed surrogate-reared pups hit development goals more quickly and survived better in the wild than young otters that got close to humans, compelling caretakers to keep their distance.

Put back into their tank, 936 and its two young tankmates, 925 and 930, raced for their food. The average otter consumes a quarter of its body weight each day. Usually the neediest of the bunch, Otter 936 showed its mettle, grabbing a crab, resting it on its stomach and twirling around while tearing it apart.

Now 38 pounds, it dove for a shell to smash open the crustacean - exactly the sort of otter-y behavior Hazan wanted to see. After more than a year in her care, 936 was ready to be released.

- - -

‘Humans have intervened enough’

The southern sea otter population today is on the mend, with roughly 3,000 living south of San Francisco nearly to Santa Barbara. But they have yet to establish themselves beyond that stretch of coast.

Right now, Central California is near capacity, said Jess Fujii, head of the aquarium’s sea otter program. “So in order for those numbers to increase, they would really need to expand their range.”

Connecting the southern sea otter with a population to the north in Washington state could help boost its chances against climate change, as rising temperatures push sharks that bite otters into new waters and ocean acidification imperils otters’ prey.

In addition to restoring seagrass beds and kelp forests, otters would draw enthusiasts to towns up the coast. The many otter stuffed animals and T-shirts for sale at shops along Monterey’s Cannery Row are a testament to the tourism draw. The U.S. Fish and Wildlife Service estimated a 13-year reintroduction program would cost between $26 million and $43 million, according to a feasibility assessment last year.

But for reintroduction to work, humans along the coast have to be on board.

The otter-loving public needs to appreciate them from afar. The renegade otter harassing surfers near Santa Cruz this summer might be emboldened because someone fed it. Government and aquarium officials are trying to capture the otter before it steals again - or, worse, bites someone.

So far, the pilfering otter has eluded authorities. “They are well adapted to the water, and we are not,” Hazan said, noting the rescue team she is on is contending with rough oceans and dense fog.

“She’s smart,” Hazan added. “She’s a sea otter.”

Crab and urchin fishers also see potential conflict with the otters, saying they would add competition at a time when climate change is putting pressure on catches. The industry has petitioned Fish and Wildlife to remove sea otters from the Endangered Species Act list, saying their numbers have grown large enough to no longer warrant protection.

Dave Rudie, a lifelong urchin diver in California, thinks he and others in his line of work can do a perfectly good job of controlling the recent urchin surge. “Humans have intervened enough,” he said. “Let’s not move them around and mess up other ecosystems with unknown consequences.”

Any reintroduction if approved would start small, said Lilian Carswell, a sea otter expert at Fish and Wildlife. “They’re only going to be in very localized areas, if we even go forward.”

The Monterey Bay Aquarium aims to play a role in improving on past reintroductions, such as one in the 1970s in which otters were transported from Alaska to Oregon. Otters from the aquarium’s surrogacy may fare better, since the youngsters have no established territory.

- - -

Tough love

During 936′s final veterinary exam before its return to the wild, Hazan briskly rubbed down the sedated animal with towels, like she did when it was a pup. She ran a fine-toothed comb down its body to get out the dead hair.

Veterinarian Mike Murray, meanwhile, gripped the otter’s back flippers and clipped tags through the webbing between the digits in each.

Out in the wild, 936 would never have a name. But it would always be identifiable by the tags’ unique color combination. Besides a small wart in its mouth, the otter had a clean bill of health.

A few days later, 936, sedative fully worn off, nuzzled its nose against its crate, sniffing its surrounding as it was transported to the sea.

Otters, for now, can be released only back into their existing range south of San Francisco. At the edge of a bed of kelp in Monterey Bay, Hazan and two other staffers heaved the crates to the edge of the boat. Unlatching the doors, they tipped the three otters overboard, into the water.

Right away, Otters 925 and 930 treaded toward the kelp. But 936 dove under the boat and attempted to climb back aboard.

Hazan had one last tough-love lesson. She spritzed a cloud of pungent spray off the stern to prevent 936 from returning to the vessel, to the life it knew.

But Hazan couldn’t fully let go yet. After losing sight of 936, she twisted an antenna atop a long blue pole on the boat in search of the signal emitting from a transmitter surgically embedded in the otter’s belly. Her staff planned to follow the three animals for two weeks to make sure they took to the wild.

“It’s not here,” Hazan said as she circled the boat along the coast. The wind picked up, and it was harder to see anything floating between the waves.

Then, through the radio static, she heard it:

Ping, ping, ping, ping. . .

“Ah, finally,” Hazan exhaled. Soon the boat came upon the otter, exploring the kelp. It was home.