A sea otter at the Monterey Bay Aquarium in Monterey, Calif., on Tuesday, May 30, 2023. The aquarium’s otter program is responsible for reestablishing much of Northern California's critically endangered Southern Sea Otter population.
Inside the Monterey Bay Aquarium, a crowd has gathered around the otter exhibit, watching the animals do somersaults in the water and paddle on their backs while clutching toys.
“Aren’t they fun?” one woman asks her companion. “Bonk,” a pint-sized spectator says, as one otter bumps heads with another. “Bonk, bonk.”
But upstairs, past locked doors and an office marked SORAC — Sea Otter Research and Conservation — a different kind of otter action is happening. Aquarium staffers use nets to wrangle three otters from a tank into plastic kennels, so they can remove mussel shells and other food debris from their enclosure. These are not the crowd-pleasing otters of downstairs. These are wild animals, brought in as pups after stranding or becoming sick. They were raised at the aquarium with minimal human contact and fiercely dodge to avoid the nets.
“We actually want them to associate this (process) as a negative interaction with humans,” says Sandrine Hazan, the aquarium’s stranding and rehabilitation manager for sea otters. She helps haul up one otter, noting, “We got the problem child first, that’s good. She just likes to climb onto the nets and make it that much more difficult to get her.”
The aquarium hopes to soon release this group of otters back into the wild, where they will join an estimated 3,000 southern sea otters living off the coast of California. The fact that there are that many is a testament to the species’ stunning recovery.
Eighteenth-century fur traders seeking their lush pelts cut the population down so completely that by the early 1900s, the otters were presumed extinct. It wasn’t until 1914, when a few dozen were spotted off Big Sur, that people realized, despite all odds, the otters were hanging on.
Conservationists working with the government have since protected and grown the otter population, perhaps none more effectively than the folks at the Monterey Bay Aquarium. Since the 1980s, the aquarium has reared otter pups found stranded or sick in the wild, initially using methods best described as learning by doing.
“Young pups are so dependent on their mother’s care that when they strand, and you are there caring for them as their mother would, they bond with you that strongly,” says Teri Nicholson, senior research biologist at the aquarium. “They consider you as their mother, and they’ll follow you anywhere.”
Nicholson and others used this maternal connection to guide young animals around their natural environment. They took pups on free-diving swims through kelp forests, collecting urchins and crabs and handing them over to the hungry youngsters. They practiced staying buoyant on the surface together, opening clams while floating on the waves, and modeled how to pound shells against rocks to crack them open (otters like to use tools).
The researchers raised the pups in inflatable kiddie pools and on waterbeds. For a time, a staffer had one living at home in their bathtub. “The caretakers became quite familiar,” notes the aquarium’s historical literature, dryly, “with the piercing scream a young otter makes.”
Though well-intentioned, direct human-to-otter contact came at a cost.
“Often a strong bond would endure in the wild after release – especially as our coastlines became more crowded – resulting in persistent interactions with humans,” says Nicholson. “So the minute we had an opportunity to try other methods, we pivoted.”
Those new methods are on display today, as a staffer dons a poncho and darkened face shield, kind of like a welder’s mask. Looking like a B-movie psychopath, she goes into an ICU room and starts fluffing an orphaned pup’s fur with her fingers, mimicking the grooming behavior a mom would do at this age.
“The idea with the disguise is it creates this amorphous shape that masks the human form,” says Hazan. “We don’t want them to form a bond, because then you have to deal with separation anxiety, and it can be difficult for them.”
It turns out that having wild otters grow familiar with people is not a great thing.
“What we don’t want is when they’re released back into the wild, they’re approaching humans, jumping on kayaks,” Hazan says. “If that were to happen, they would potentially have to be recaptured and (be) unable to be released back into the wild.”
Despite how fun it sounds, you actually don’t want an otter on your kayak. Aquarium staffers wear heavy Kevlar gloves when handling otters. Even so, Hazan’s hands have bite marks.
Otters, she says, “are very charismatic and adorable, but they’re also dangerous. If they want something, they’re going to use their teeth or their paws to try to get it. And the way they play or roughhouse, they can inflict injury even without being aggressive.”
So rescued otters in the program are effectively blinded to the sight, sounds and smells of humans, which raises the question – who’s actually doing the hard work of raising the pups?
Other otters, naturally.
In the 1990s, aquarium staff working in the field noticed adult female otters caring for youngsters even when they weren’t biologically related. In 2001, they got a chance to observe this behavior in a controlled setting, when they simultaneously had an otter mom lose a pup to stillbirth and received an orphaned pup from a local beach.
“Both animals were in distress – the female at the aquarium was vocalizing for her dead pup, and the orphaned pup we’d picked up was vocalizing for its mother,” says Nicholson. “So we introduced them and within minutes, the two resembled a natural mother-pup pair.”
That quickly became the new way of doing things. Now, when a pup is discovered helpless in the wild, the aquarium often pairs it up with one of the captive otters from the public exhibit. The two go into a private tank together, where the surrogate otter mom teaches the pup skills it needs to survive outside. After the pup is released into local waters, the mom goes back on exhibit until the next time duty calls.
Some of the surrogates have raised more than a dozen wild pups. But do they actually enjoy it?
“Each female is different, and each introduction between mom and pup is different. Just like we all feel different on different days,” says Nicholson. “Sometimes the bond can happen immediately, and on other occasions, it can take more time. We’ve had mother-pup pairs who have switched pups.”
Otter fathers are not involved, because — as in the wild — they’re not really needed at this point.
“Not unlike many mammal populations, the female is the primary caregiver, and the male contributes his sperm,” Nicholson says. “The males are holding territories, mating with other females, while females are just rearing their young.”
Seventy-five percent of the pups reared in the surrogacy program have gone on to establish themselves in the wild and contribute to the population’s growth (compared to just 31 percent without surrogates). The results are on shining display in the Elkhorn Slough, a 7-mile-long body of water just north of Monterey. The aquarium used to release otters here, because it’s sheltered and has no sharks, but the slough has reached capacity now.
On a recent afternoon, southern sea otters spanned all sides of the water, doing somersaults to remove parasites and clean their fur, sticking paws up to warm in the sun, wrapping themselves in eelgrass to take little naps. You could see some otter mothers – distinguishable due to nose scars incurred during mating – demonstrate behaviors to pups, including grooming and cracking clam shells.
It’s thought surrogate otters and their progeny have contributed to more than 50 percent of the population growth in Elkhorn. And the slough has benefited from the otters’ presence – they’ve kept other species from overpopulating and doing damage and boosted the growth of native seagrass beds, which in turn, act as carbon sinks.
“As that population built up in Elkhorn Slough, we saw a lot of improvements in ecosystem health in just that area,” says Cara Field, medical director at the Marine Mammal Center in Marin.
“There’s a lot of interest in helping to restore our entire (Pacific) coastline to a more healthy ecosystem. And otters might have a really significant role to play in that. That’s what we are theorizing, anyway, those of us who are interested in otter reintroduction.”
Back at the aquarium in their permanent homes, surrogate moms never get to see the benefits they’ve made to the Monterey Bay landscape. But they have their little pleasures. Take Rosa, a surrogate mom who has reared an incredible 15 pups.
“She was a phenomenal surrogate, very consistent from pup to pup in how maternal she was,” says Hazan.
At 23 years of age, Rosa is now retired. And what is retirement like for an otter?
“I mean, luxury,” Hazan says. “You get whatever you want, all the crab you want. You don’t have to deal with any annoying pups – you don’t have to take care of anybody. You can be grumpy and irritable and decide you don’t want to eat something one day, and then like that something the next day. Everything will be catered to you, so it’s pretty amazing.”
