Hakai Magazine

Coastal science and societies

A young Harbour Seal (Phoca vitulina) on the beach of Rottumerplaat
On the Dutch island of Rottumerplaat, a young harbor seal rests. Mothers often leave their pups on shore while they forage; it’s a natural behavior that is sometimes mistaken for abandonment. Sick, injured, and/or presumed orphaned seals found on beaches are handled very differently by the countries along the Wadden Sea. Should the animals be rescued, euthanized, monitored by experts, or left alone? And who gets to decide? Photo by Buiten-Beeld/Alamy Stock Photo

Reassessing Seal Rescue

The Netherlands is trying to do something new when it comes to rescuing “stranded” seals: less.

Authored by

by Cathleen O’Grady

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Streya was born in summer on a wide, windswept beach on the Dutch coast of the Wadden Sea. At a week old, the tiny harbor seal pup—about the size of a small corgi—was alone on the beach, no mother in sight. Then she was snatched. By the time the well-meaning beachgoers presented her to a local animal rescue network, there was no possibility of reuniting the pup with her mother.

For two hours, Streya cowered in a large wicker basket in the back of a moving vehicle swaying its way to a seal sanctuary in the remote village of Pieterburen. The animal rescue team had called ahead and now, with Streya’s arrival imminent, Sealcentre Pieterburen is a flurry of activity. “Check that there’s no seal poop in the shoes,” advises seal researcher Andrea Ravignani as he hastily hands me clogs and scrubs. I pull on the borrowed gear and join the throng of vets, nurses, volunteers, and researchers preparing to meet the pup.

From the information relayed by the rescue network volunteers, it sounds to the center staff like there’s nothing actually wrong with Streya. They would have preferred to observe her on the beach to ensure that her mother hadn’t just left to grab a quick meal, a common behavior among harbor seal mothers. While a weaned pup could be checked by the staff and safely released, Streya, still nursing and only a week old, will need to be hand-fed. The center will have to raise her to the point of independence, focused all the while on trying to keep her wild.

The seal nurse opens the wicker basket, quickly grabs the trembling Streya behind her head and lays her on the tiled floor of the cold, brightly lit intake room. Carefully straddling Streya, she holds her in place while the vet makes her way through a blisteringly efficient checkup, taking the pup’s temperature and a blood sample, estimating her age, and checking for signs of illness or injury. Streya claws at the nurse’s hands, and when the needle pierces her skin, she startles and tries to bite.

“Usually they’re not this polite,” says the vet. Streya doesn’t seem polite to me. She seems terrified, and understandably so. Dogs often hate the vet, and they’re well acquainted with humans. For a wild animal, this intervention is nothing short of an alien abduction. As the vet feeds a silicone tube down Streya’s throat for a dose of “salmon porridge,” it’s difficult to watch the pup struggle—doubly so knowing that she might have fared just fine in the wild.

seal pup with injured eye at a seal sanctuary in Pieterburen, Netherlands

Orlando, a young seal pup with an injured eye, has been picked up by a trained volunteer and brought to a seal sanctuary in Pieterburen, Netherlands. Here, veterinarian Anna Salazar Casals (right) and Enrique Rubio García assess the seal’s health as part of the center’s intake procedure. Photo by Kati Auld

“Pup-napping” like this is a common occurrence, says Arnout de Vries, who coordinates the Pieterburen center’s responses to stranded seals. In the Netherlands, it’s legal for any member of the public to take a distressed seal—or a seal they interpret to be distressed—into their care for up to 12 hours, before handing it over to a licensed rehabilitation center. In some people’s understanding of the law, seal rescue is more than permitted: it’s obligatory. Sealcentre Pieterburen, alongside its fellow Dutch rehabilitation centers Ecomare and A Seal, wants to change this, making it illegal for anyone other than trained specialists to remove seals from the beach.

A new agreement on seal rehabilitation standards, due to be finalized in spring 2019, is a moment of reckoning for the Dutch relationship with its seals. That relationship has an emotive history, from the devastation of the local seal populations after centuries of hunting, to protective legislation in 1962, to the headline-grabbing stunt that sparked the country’s seal craze when activist Lenie ’t Hart nursed a lone seal pup back to health in a bathtub.

These days, the Netherlands has seal fever. Most children in the country have at some point visited one of the three major seal rehabilitation centers, whether with their family or on a school trip, says ethicist Franck Meijboom. Decades of awareness campaigns have urged Dutch people to be on the lookout for abandoned seal pups on the beaches. And the seals themselves have bounced back; 500 harbor seals in 1980 boomed to 9,000 in 2016, while gray seals, entirely absent from the Netherlands in 1980, reached more than 5,000 in 2016. The vast majority of those seals live in the Wadden Sea, with smaller populations in other areas.

Map showing worldwide ranges of harbor seals and gray seals

Worldwide ranges of harbor seals and gray seals. Illustration by Mark Garrison

But with the recovery of the seals, a new approach to rehabilitation has begun to gather momentum—one that emphasizes the integrity of a wild population, and is taking a hard look at the unintended effects of human intervention.


In the early days of rehabilitation, every seal’s life counted toward the recovery of the Wadden Sea seals. Now, numbers of harbor seals in the region are staying roughly level, suggesting that the local ecosystem is reaching capacity. On a global scale, the outlook is similarly sunny: gray seals, found throughout the North Atlantic and the Baltic Sea, are listed by the International Union for Conservation of Nature as being of least concern—not even remotely threatened. Aside from one endangered freshwater subspecies in northern Quebec, harbor seals, abundant across the coasts of the northern hemisphere, also have the least concern status. “From a population viability point of view, there is no reason at all to rehabilitate [gray or harbor] seals,” says Danish marine biologist Anders Galatius.

And yet rehabilitation of both harbor seals and gray seals is widespread internationally. Britain and Ireland are home to a cluster of seal rehabilitation organizations. The Vancouver Aquarium in British Columbia takes in injured and orphaned harbor seals, alongside other marine mammals in need of help. And the Marine Mammal Center in California takes in a limited number of harbor seals per year, mostly those born on beaches popular with humans (and their dogs).

The three countries on the Wadden Sea—Denmark, Germany, and the Netherlands—have an agreement stipulating that each country should have a seal conservation plan. But the agreement leaves a great deal open for interpretation, resulting in three different approaches. In Denmark, seal rehabilitation ended in 1995. These days, if a sick harbor seal is found on a beach and judged to have no chance of recovery in the wild, it’s promptly euthanized. “They’re shot,” says Galatius. (Danish conservation guidelines specify the caliber of firearm to be used for different sizes of animals to ensure a quick and safe death.)

Seal being tube fed at Sealcentre Pieterburen in the Netherlands

As part of his intake procedure at Sealcentre Pieterburen in the Netherlands, Orlando is being tube fed a dose of “salmon porridge,” an emulsion of salmon and any necessary medications. Photo by Kati Auld

Seal rehabilitation centers in Germany help orphaned or injured seals, but unlike Dutch wildlife officials, German wardens will shoot a seal if it seems like a poor candidate for rehabilitation. Ending a life swiftly with a bullet is a common method in wildlife management worldwide, preferable to restraining a wild animal for treatment or chemical euthanasia, says Sealcentre Pieterburen’s de Vries. “It’s way quicker and more respectful to the animal.”

In the Netherlands, though, the standard procedure is taking all needy seals to rehabilitation centers, where euthanasia has historically been treated as a last resort. This necessarily entails restraining the animal, and possibly even driving it for hours to the nearest center. You have to wonder who we’re trying to protect when we don’t just euthanize on the spot, says ethicist Meijboom.

In its queasiness about euthanasia, and in sheer numbers of rehabilitated seals, the Dutch are regional outliers. Between 2003 and 2013, approximately 20 percent of the harbor seal pups born in Dutch waters made their way through centers like the one in Pieterburen. By comparison, only around five to 10 percent of pups were rehabilitated in Germany and England between 2003 and 2007. The high rehabilitation rate in the Netherlands, peaking at half of all pups born in 2011, is partly the result of people taking lone seal pups from beaches and leaving them with seal centers, which then have little choice but to rehabilitate them.

For 40 years, the Dutch public was told that if you see a pup alone then it’s orphaned, it needs help and you need to help it, says Ana Rubio García, head vet at Sealcentre Pieterburen. When I ask where that message comes from, she says “here,” and points to a large poster. Adorned with the center’s logo, it depicts a pleading seal entreating the reader to “make a crying seal pup smile” by adopting it through regular donations to the center.

Dutch people are raised with the perception that seals are helpless and desperately in need of human assistance to survive, says Sander van Dijk, Sealcentre Pieterburen’s director of content and education. The emotive poster is now kept in the facility’s staffroom, away from visitors. “Maybe we should turn it around and not look at it anymore, just so we don’t go crazy ourselves,” van Dijk says with a laugh. He has presided over a drastic change in the center’s messaging: these days they urge the public to leave seals alone and call trained volunteers for help if they find a pup.

Sealcentre Pieterburen began its overhaul after a schism in early 2014. The staff had instituted a new policy permitting seals to be released after a shorter period in the center, but Lenie ’t Hart—who had founded the center after her initial foray into seal rehabilitation in her bathtub—disagreed with this approach. The dispute led to a well-publicized power struggle, with ’t Hart and her allies accusing the staff of breaking the law with their new release policy. A staff rebellion and strike culminated in ’t Hart leaving the center.

An illegal rehabilitation network subsequently sprang up among seal lovers, including ’t Hart, who were disgusted by the changing ethos at Sealcentre Pieterburen. When a member of the network was arrested for rehabilitating seals at his home, he cited his mistrust of Sealcentre Pieterburen in defense, saying that he used to take needy seals to the facility, but that he no longer had confidence that its staff would look after the seals properly. When he and another man were prosecuted for the offense, the judge dismissed the charges on the grounds that the men believed that transferring the seals to Pieterburen would have conflicted with their duty to care for the needy animals.

Seals in pool at Sealcentre Pieterburen

When seals arrive at Sealcentre Pieterburen, they are initially quarantined. Later, they may be placed with other pups for company, with limited swimming sessions in a small tank. Older pups, such as the ones shown here, are eventually placed into an outdoor pool where they can move in and out of the water at will. Photo by Kati Auld

In March 2016, state secretary for economic affairs Martijn van Dam granted ’t Hart and her allies a license for seal rehabilitation, allowing the network to operate legally. But in a letter to the Dutch House of Representatives, van Dam pointed to the growing divide in seal rehabilitation philosophies and installed a scientific advisory committee to suggest a way out of the impasse. The committee’s advice sketches out the tension at play in the two rehabilitation philosophies, both echoed in Dutch law: on the one hand is the integrity of a wild population, free from human interference; on the other is the right of every seal to be helped if it is sick or injured.

The committee’s suggestions for new practices, released in February 2018, propose limiting rehabilitation to no more than five percent of all the gray and harbor seal pups born in a year, and not rehabilitating malnourished seals when the populations are thriving. Exceptional disease outbreaks aside, highly diseased animals would be euthanized, leaving rehabilitation efforts to focus on orphaned pups and seals injured by human activities, like fishing.

These proposals are vociferously opposed by ’t Hart. Now in her 70s and still as fiercely committed as ever, she has recently returned from a trip to the Caspian Sea in Iran where she travels regularly “for the seals,” she tells me. When we speak by phone, she is unable to contain her horror at the new proposals, brushing aside the careful arguments with an appeal to the heart. “My philosophy is very simple: when there is an animal in distress, you have to help it.”

But how do you determine if an animal is in distress? And who gets to decide?


Conflict swirls around one problem in particular: solitary pups. Well intentioned members of the public lifting pups like Streya is one part of the problem, but staff at the Pieterburen center are also concerned about overzealous seal rescue networks removing pups from the beach too readily. The scientific advisory committee recommends a waiting period of at least 24 hours to determine whether a lone seal pup is definitely orphaned before taking it to a rehabilitation center, a proposal supported by the major seal centers but ardently opposed by ’t Hart and her allies.

Seal being hand fed at Sealcentre Pieterburen

This seal pup has graduated from fish porridge to solid food, but still needs help learning to swallow fish whole like a wild seal. Once the pup is eating whole fish without assistance and has gained enough weight, it will be released back into the wild. Photo by Kati Auld

The goal of the observation period is to give foraging mothers plenty of time to return to their pups, a policy that may have saved Streya from being unnecessarily orphaned and spared her mother the unimaginable distress of losing her pup. But it may also have diminished Streya’s chances of survival, says Sue Wilson, a seal researcher based in Northern Ireland. Her research describes how a harbor seal mother will leave her pup on shore while she forages at sea, returning to reunite with it later. This observation, alongside other research and global seal rehabilitation practices, informs the committee’s recommendation of a 24-hour observation period.

Wilson, however, considers an ironclad rule of 24 hours to be “a blunt instrument.” A trained, experienced professional shouldn’t always need 24 hours, she argues—and in some cases, quick intervention may make all the difference. The essential deciding factors, she says, should be the location, size, and condition of the pup, since seal moms don’t forage when they have newborns. In fact, “mothers tend not to leave pups on shore until they’re about 10 to 14 days old,” putting them at around 15 kilograms or more. A longer period of observation might be appropriate for an older, fatter pup, but, according to Wilson, “if it’s away from the main colony, in an unusual place, and at or under birth weight, which is around 11 kilograms, it is 99 percent certain to be an orphan.”

When Streya arrived at Pieterburen, she weighed a mere 9.6 kilograms and was estimated to be less than 10 days old. By Wilson’s criteria, she was undoubtedly an underweight orphan, in need of help as quickly as possible. The swelling on her mouth and the busy beach where she was found, says Sealcentre Pieterburen’s de Vries, may also have been reason enough to admit her, had she been observed by an expert. The proposals make room for discretionary intervention in cases like this, where a 24-hour delay is unwise. The new default, though, would be to wait, observe, and not snatch immediately. And for older, weaned seals, there may be another threat demanding human intervention.


On a wet, freezing October morning, I arrive at Dutch seal sanctuary A Seal to find the staff clustered around the freshly delivered corpse of an adult male gray seal. He lies on his back on the wet concrete, the vet’s slender frame tiny against his 250-kilogram bulk as she bends over to examine him. A trickle of blood oozes from the seal’s mouth and mingles with the rainwater in a bloody rivulet. “He smells of oil,” observes the center’s manager, Karola van der Velde. But it’s not clear what killed him, and he’s bundled off to Pieterburen for a necropsy.

A Seal, a relatively young rehabilitation center in the highly populated province of South Holland, opened in 2014 to help the seal populations off the Netherlands’ southwest coast. Now that the summer harbor seal pupping season is over and most of the orphans have been released, the patients here are mostly older, weaned juvenile harbor seals infested with parasitic lungworms. Lying alone or in pairs in their glass-fronted pens, they lazily watch the hubbub of construction as A Seal builds a temporary exhibit in its visitor center. Outside, seals nearing their release dates lounge together around larger swimming pools, oblivious to the rain and cold.

Map of the Wadden Sea and seal sanctuaries in the Netherlands

Illustration by Mark Garrison

Lungworm infestation isn’t something affecting the occasional unlucky harbor seal pup—it’s an infectious rite of passage for almost all seals, beginning when the pups wean and start eating fish, some of which are thought to carry lungworm larvae. The larvae migrate through the organs, reaching the heart and lungs, and eventually reproducing in the airways. Seals then cough up a new generation of larvae, which they swallow and pass on through their feces.

Many pups make it through the disease without too much trouble. Others, though, can have difficulty breathing, with the infestation sometimes leading to complications like pneumonia. Afflicted pups, struggling to dive for food, may be found sick and emaciated on the beach. The scientific advisory committee’s advice would reduce the number of these pups being taken into care, suggesting instead that lightly affected animals should be left alone as long as possible, and that pups with terrible lungworm infections should be euthanized.

Young seals need to develop their immunity to the parasite, and some researchers think that interfering with this unpleasant but ubiquitous process could harm the population as a whole. There’s evidence, for instance, that inbred animals might be more likely to succumb to lungworm infestation. If that’s the case, the animals that make it through the ordeal on their own might be genetically healthier, while those found sick on the beach may be more inbred. By medicating these genetically unhealthy seals to help them survive a lungworm infestation, humans may be returning more inbred seals to the population, slowly weakening the genetics of the population over time.

A lack of data on the fate of rehabilitated seals makes it difficult to assess the impact of human interference. If rehabilitated seals ultimately succumb to lungworm anyway, then putting them through the stress of rehabilitation is ethically questionable. And if they survive because of human intervention, there’s a risk of short circuiting the natural selection against weaker animals. Rehabilitating a seal devastated by lungworm infestation “may work for that individual in the short-term, but might not be the best for the population, and in the long-term, might not be best for that individual either,” says Simon Goodman, an evolutionary biologist who sat on the scientific advisory committee.

The seal rescuers who side with ’t Hart’s approach, including animal rescue organization DierenLot and the Eemsdelta Seal Sanctuary, are infuriated by the proposal to limit rehabilitation for seals with lungworm. Both organizations, along with the Lenie ’t Hart Seal Fund, have withdrawn from the roundtable stakeholder discussions held to turn the scientific advisory committee’s advice into new practice and legislation. In a letter explaining its position on the advice, DierenLot writes that the new guidelines overlook evidence that human-caused pollution drives up incidences of lungworm infestation.

Lungworm rates have indeed increased, but the committee was unconvinced by the argument that this is due to pollution. Committee members acknowledged that pollution in the Wadden Sea could affect seals but reasoned that since there’s no evidence of increasing pollution it couldn’t directly explain the rise in lungworm infection. The growing number of gray seals, which may also host the lungworm parasites, is a potential culprit.

Hungry seals are more likely to succumb to lungworm, and their fellow seals are not their only competitors: human fishing activity in the region could also play a role. Understanding why so many pups strand with lungworm and low birthweight needs investigation, says seal researcher Wilson, but “there are so many questions to ask that haven’t been asked.” Where are the pups stranding, for instance, and are the contaminant levels higher, or fish densities lower, in those areas?

Currently, these questions remain unanswered. To puzzle them out, researchers must track rehabilitated seals and understand the impacts of human activity in the region. But without this information and an understanding of how rehabilitation affects seal populations, and with a population of a healthy size, says ethicist Meijboom, “you should be very hesitant to do anything.”


After her intake, Streya is moved into quarantine, a precaution to ensure that she doesn’t pass any viruses or other infections to her fellow orphans. I visit her in her small pen, where she’s allowed to have a quick swim in a tiny pool under close supervision. The pool is one of many laid out in rows in an airy barn, where the acrid, seaweedy tang of seal poop creeps into my hair and my clothes, lingering for days.

Seal being fed at Sealcentre Pieterburen

Benedicte Eftevand feeds whole fish to seal pups in the outdoor pool at Sealcentre Pieterburen. Happily guzzling whole fish means that these seals are nearing the point of being ready for release. Photo by Kati Auld

In a crowded field of unbearable cuteness, Streya stands out, with a sweet heart-shaped face and impossibly huge eyes. She flops toward me, her face pleading and extraordinarily puppy-like, giving every impression of begging for food. Her technique is flawless: my primate brain is ablaze with the urge to feed, soothe, protect.

“I don’t think any of this rehab is beneficial from a population perspective,” says Wilson, who has rehabilitated small numbers of seals herself. “I don’t think that’s why pups are rehabbed, at least not harbor seal pups in western Europe.” It’s not to do with conserving the population, she says, but rather the welfare of the animals. “You have a little animal which cannot survive, and it’s in distress. There’s an issue of moral proximity: if you’re beside it and you see it, it’s difficult for any compassionate human being to walk away.”

If you don’t see it, though, nature can take its course. The new Dutch guidelines would forbid entering closed conservation areas to look for stranded seals, a practice that has been reported. “We should at least not actively search for all kinds of animals who are at the moment of dying and then say well, we now have to intervene,” says Meijboom.

What the Netherlands needs, he adds, is a new way of thinking about how to look after its seals—an understanding that sometimes, holding back and not intervening immediately could be the best way to help. The enthusiasm for seals is wonderful, he says, so “if you use that positive energy that volunteers have, but if you are a little bit more reluctant, a little bit more careful, and a bit more critical, then maybe you can help those seals at least as much as you think you’re doing now.”

The illusion of Streya’s domestication is short-lived. With her long, flexible neck comfortably drawn in, her face is a picture of goofy, triple-chinned contentment. But she quickly becomes snake-like and predatory when her neck extends, her head whipping around to get at the human hands on her back. The seal nurse holds Streya down in her dry pen and instructs me while I attempt to take her rectal temperature. It’s a doomed endeavor. Her rear flippers repeatedly slip from my grasp and I give up for fear of ineptly jabbing the thermometer into the tender folds of skin near her anus.

The pup is strong and clearly loathes the contact with humans. The guidelines at Pieterburen are designed around minimizing this stress, so human contact with the seals is limited. All medical care and research happens alongside feeding, requiring just a few minutes of physical contact with humans. Initially the interactions occur four times per day and lessen in frequency until the pups can eat independently and no physical contact is needed. “If the animals would benefit from hugging, I’m sure we would have lovely hugging sessions,” says van Dijk. “But the reality is that they don’t.”


“Once you start intervening,” says Meijboom, “you cross a line.” The near-annihilation of seals in the Netherlands was a good reason to cross that line, he says, “but it’s more difficult to say that now we’ll stop.” Building up the infrastructure for rehabilitation has taken decades, and there seems no chance of dismantling it any time soon. “We are so far off natural [in the Netherlands],” says van der Velde, the manager at A Seal. “We fought the water, we made the land—we made everything. So I think it’s in our culture to say, if we can make things, we can heal things.” Dutch seal rehabilitation is probably here to stay.

There are benefits to maintaining the practice even if the seal populations don’t strictly need it, says Lindsaye Akhurst, a vet and the manager of the Vancouver Aquarium’s Marine Mammal Rescue Centre. When we do get animals that are endangered or threatened, we know what to do. We have that volunteer base, the medical knowledge, and the equipment.” Then there’s the boon for research, she adds: the samples taken from animals in rehabilitation are enabling research into how humans are affecting the ocean. Ongoing work uses seals as a sentinel species for understanding problems like antibiotic resistance, and the effects of microplastics and other pollutants.

For Machteld Geut, the chief vet at A Seal, the seal carries the flag for environmental awareness in the Netherlands. “These animals are ambassadors for the population, ambassadors for the wild; but also ambassadors for the world, for the sea.” The appeal of the seals lures visitors to the rehabilitation centers, where the staff have the opportunity to inculcate concern for nature more broadly, she says.

A harbor seal swimming in a pool at Sealcentre Pieterburen

A harbor seal at Sealcentre Pieterburen enjoys time in the outdoor pool. Harbor seal pups brought to the sanctuary as orphans will usually be released after spending two to three months in rehab. Photo by Kati Auld

A Seal opened to save already traumatized and sick animals found on the west coast from the ordeal of traveling three hours or more to Pieterburen, on the other side of the country. While the Pieterburen seal center sits on a tiny village main street with two restaurants, a campsite, and not much else besides, Geut’s office overlooks a buzzing road alongside a series of enormous wind turbines, chugging with 21st-century industrial might. Just 30 kilometers from Rotterdam, home to Europe’s biggest port, human presence in the region is inescapable.

In a region like this, Geut says she wonders what constitutes wildness. When a beach is being cleaned and taken care of, when it’s full of tourists, and people are drinking and holding parties, is that a wild area? “I don’t know,” she says, adding that some of the seals that come into the center have bare bellies, their coats worn off by inching along on concrete.

The integrity of wildness plays an important role in the ethical thinking behind the new science advisory committee’s recommendations. “Nature has a certain autonomy,” says Meijboom. “Nature can be out there and survive better without us than if we intervene. If a population is in balance without human intervention, you could question what good we could bring.”

But ’t Hart, and those who think like her, disagree. The seals in the Netherlands, she wrote to the committee, are faced with so much human interference that considering them wild is inaccurate. But the population seems to be thriving nonetheless—although probably at lower numbers than would be possible in a world without humans, says marine biologist Galatius.


Streya is eventually released in late August on Terschelling, one of the islands dotting the Wadden Sea. I wasn’t there, but I can imagine the joyful occasion—the opening of Streya’s crate on the beach, her first few tentative hops, and eventually her first plunge into the wide, wild sea.

Months later, as a crisp, chilly autumn day descends over the coast, I visit Texel, the largest of the Dutch Wadden islands. Even on these small islands, as rural as the Dutch countryside ever gets, human presence is overpowering. The ferry to the island sails from Den Helder, the town where Streya was found, and the view back toward the harbor is thick with industry, shipping, fishing, wind turbines. On the island, I walk through the grassy dunes, seashells crunching in the gravel that works its way into my boots. The sea is not visible from the dunes, but buildings are.

Behind me is the Ecomare aquarium, home to the oldest seal rehabilitation center in the Netherlands. A crowd is enthralled by a keeper feeding a gaggle of harbor seals that permanently reside in an enclosure the size of a large suburban swimming pool. One enclosure over, two porpoises named Dennis and Michael swim endless laps, the blank aquamarine walls of their pool glowing faintly in the weak autumn sunlight. Beached as calves and brought to Ecomare, they would have died if released back into the wild, the information plaques tell me. Here in their enclosure, they are safe, circling back and forth. Perhaps death would have been a better alternative, I think.

Animal keeper feeding fish to blind seals in the seal shelter Ecomare, Texel, the Netherlands

An animal keeper at Ecomare, a Dutch seal rehabilitation center on the island of Texel, feeds gray seals in the center’s outdoor pool. Photo by Arterra Picture Library/Alamy Stock Photo

There is a paradox in saving animals, Galatius points out: population growth comes at the expense of individual welfare. A single seal in an underpopulated environment will prosper, catching all the fish it wants, with no risk of starvation in sight. A larger population brings with it harsher competition for food and a harder life for the seals. If you want to see a population at carrying capacity, he says, “the lives of individual seals will deteriorate.” A thriving population also means that more seals are around to get sick, starve, die, and be found on beaches by concerned humans.

Streya’s fate is unknown. If, one day, she is found by humans again, and taken to another seal rehabilitation center, the tag clipped to her flipper will tell the staff about her history. Perhaps she will succumb to lungworm, or struggle to find enough food. Perhaps she will thrive. Without close monitoring of released animals, the myriad humans dedicated to saving seals like Streya don’t yet understand the effects that ripple out from their good intentions. But in the paradox they have created is a strange certainty: more dead seals are the inevitable consequence of saving the seals of the Wadden Sea, and of keeping them wild.