In the Göta river, upstream from the massive stone ramparts of the Bohus Fortress and the estuary in Gothenburg, strong currents churn the murky waters.
There’s a palpable sense of history along this stretch of Sweden’s west coast: the medieval castle, strategically located on the former border between Denmark and Norway, was besieged 14 times, yet never taken by force.
Today, an equally well-planned but far more benevolent campaign is poised to make its own history.
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Inside a large metal cage, which has been partially suspended in the Göta’s dark, swirling waters for two days, a school of 25 torpedo-shaped fish perform lazy circles, deftly avoiding one another with flicks of their pectoral fins.
Linnéa Jägrud, a freshwater scientist working for the Swedish Anglers Association (Sportfiskarna), reaches over from a pontoon and slowly lifts a hatch on one side of the cage.
As a shaft of sunlight pierces the underwater gloom, the first fish cautiously noses its way out of the enclosure and slowly disappears downstream. For the first time in more than a century, an Atlantic sturgeon is swimming freely in Sweden’s largest river.
“It was an amazing moment,” says Linnéa. “I was nervous, relieved and elated all at the same time – I actually had goosebumps. One of my ancestors worked as a soldier in the Bohus Fortress in the 1600s.
“When he stood on the walls and looked down on the Göta flowing below, there would have been Atlantic sturgeon swimming in the water. Knowing that I’d played a role in bringing this majestic fish back to the same river – which was the culmination of collective efforts over many, many years – was very special.
“I’m looking forward to the day we can look at the Göta and say, ‘There are Atlantic sturgeon spawning here once again.’”
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Living fossils
The Atlantic sturgeon, one of 26 sturgeon species found across the world today, is an extraordinary fish with an ancient lineage stretching back at least 70 million years – a time when the mighty Tyrannosaurus rex ruled the Earth.
The sturgeon family itself is even older, dating back about 200 million years – at which point the Earth’s land mass comprised two supercontinents instead of the seven continents we know today. With such a long evolutionary history and a body design that has remained virtually unchanged, it’s little wonder sturgeon are often called ‘living fossils’.
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Sturgeon have retained many primitive features that have been lost or modified in most contemporary fish species. Instead of true scales, for example, the body of the Atlantic sturgeon is covered with five rows of bony plates called ‘scutes’, which resemble the armour seen on certain dinosaur fossils.
They also possess long, whisker-like feelers near their mouths, which they drag along the river or ocean floor to detect prey before vacuuming it up. Just like salmon, they migrate between freshwater and saltwater, returning to the rivers where they were born to reproduce.
They can live for more than 90 years, grow more than four metres long, and weigh more than 350kg – about the same as an adult female polar bear. And their slow rate of maturity is also remarkable: males typically start breeding between the ages of 8 and 12, while some females don’t spawn until their 20th year.
“The Atlantic sturgeon – and sturgeon in general – are weird, crazy, unique fish,” says biologist Dan Calderon, who conceived of the idea of reintroducing Atlantic sturgeon to the Göta River back in 2014.
“The fact that these prehistoric marvels have been around for such a long time is a real wonder, and testament to how successful they are. They were once considered so impressive they were granted royal status in many countries and known as the ‘king of fish’.”
“Atlantic sturgeon are definitely very cool,” agrees Linnéa. “Every aspect of their behaviour and appearance is fascinating. A 120-year-old female can still produce eggs, which is pretty mind-blowing.
“They are even known to leap out of the water, which is unusual for large, bottom-feeding fish. Nobody knows why for sure – some people think it loosens parasites, others because it just feels good. The latest theory is that the leap-and-splash is a way of loosening eggs before spawning. These fish may have been around for millions of years, but we still have a lot to learn about them.”
Resilient and adaptable, sturgeon have survived countless challenges throughout the course of their existence. Yet today, human activity has pushed them to the brink of extinction.
Sturgeons under threat
Over the past 50 years, populations have collapsed worldwide due to overfishing, poaching, habitat destruction, pollution and the construction of dams that block their time-honoured migration routes.
Climate change further threatens their survival by altering the water temperatures and quality essential for spawning, while slow reproductive rates hinder population recovery. As a result, every sturgeon species on Earth is now listed as Endangered by the International Union for Conservation of Nature (IUCN).
The main range of the Atlantic sturgeon lies along the eastern coast of North America, stretching from southern Canada to Florida – though numbers here have declined dramatically. A separate population, believed to have crossed the Atlantic around 10,000 years ago, once inhabited northern Europe, including the Baltic Sea region.
However, a combination of pressures drove the species to functional extinction in Europe during the latter half of the 20th century.
“When I started working to restore the Atlantic sturgeon population in the Göta River around three years ago, there were 27 sturgeon species distributed across the world,” explains Linnéa.
“Since then, one has become extinct in the wild. This makes me incredibly sad. It also makes me even more determined to support the comeback of sturgeon here.”
A centuries-old discovery
Atlantic sturgeon swam in the Göta River for at least 6,000 years before overfishing, hydro-power stations and poor water quality saw them disappear in the early 1900s. But before the authorities could green-light their return, they needed convincing that these fish had also spawned there.
“I heard my first story about Atlantic sturgeon in the Göta when I was 12,” says Dan. “I was on the river with my brother and we met an old fisherman who told me that he had caught sturgeon as a boy.
“Since then I have heard more of these stories, but there has never been any photographic evidence that these fish bred in the river. Just rumours.”
Having committed himself to a reintroduction initiative, Dan began planning how it might work. But he still lacked the necessary proof. Then, in 2016, he received a phone call from Kenneth Lundin, an associate professor and marine biologist working at the Gothenburg Museum of Natural History.
“He told me they had just discovered three small specimens of sturgeon in a basement at the museum, which had been caught in the Göta River in the mid-1800s,” says Calderon.
“As they were juveniles – and juvenile sturgeon are unable to survive in saltwater – this proved that the fish hatched in the river. It was the breakthrough we were looking for.”
Back from the brink
In total, 100 10-month-old sturgeon – each around 60cm long and 700g in weight – were released into the Göta in 2024.
With support from the European Wildlife Comeback Fund of Rewilding Europe, the reintroduction was carried out in collaboration with the University of Gothenburg, the Swedish University of Agricultural Sciences and the Gothenburg Museum of Natural History, as well as sturgeon experts from the German Leibniz-Institute for Freshwater Ecology and Inland Fisheries in Berlin.
In 2025, the ongoing reintroduction programme saw another 140 sturgeon of a similar age released into the Göta, together with around 2,000 fry. Working in partnership, Linnéa and Dan have now built a facility next to the river where sturgeon can be stored over the winter. These will be released next year. All are sourced from a well-established breeding facility on Germany’s Baltic Sea coast.
“Moving forwards, it’s important we release fish every year, because a lot of them – especially the smaller ones – will be eaten by predators,” says Linnéa.
“My hope is that we can eventually release between 5,000 and 10,000 young sturgeon a year, and a number of larger fish as well.
“We’re striking a balance by releasing larger and smaller fish at the same time. The smaller fish are more vulnerable, but those that do survive will probably have a stronger instinct to return and spawn here. Given the time it takes for Atlantic sturgeon to reach breeding age, it might be 14 or 15 years before we reach that point.”
Prior to their release into the Göta, the larger sturgeon are fitted with acoustic transmitters, allowing the reintroduction team to monitor their movement and behaviour.
“We saw the first fish leave the river in the autumn last year and ‘kiss the ocean’,” says Linnéa.
“Sturgeon develop a tolerance for salinity as they age and grow – and the sea was still too salty – so it swam back. After one year, 28 per cent of them were still in the river, which shows there is enough food. But they will all swim out to sea eventually.”
Compared to the situation a century ago, the water quality in the Göta has improved and the river system is now relatively biodiverse, with a range of habitats.
“Sturgeon play an important role in maintaining the health and balance of aquatic ecosystems, so their return will have a positive impact,” says Linnéa.
“But beyond that, by tracking their movement, we can identify which parts of the river are in good condition and which still need restoration. These fish can serve as the Göta’s ecological ambassadors.”
Linnéa hopes that the reintroduction of Atlantic sturgeon in the Göta will not only act as a stepping stone for the recovery of the river itself, but also for sturgeon species across Europe. Today, captive breeding and release programmes are working to restore sturgeon populations in countries such as France, Germany, Estonia and Italy.
“There’s a long way to go before we can say that European sturgeon species have recovered, but we’re on the right track,” she says.
“Records show that in 1432, a fisherman caught a big sturgeon in the Göta River and gave it to the King. The King asked what he wanted in return, and suggested a roll of woollen cloth. The fisherman thought for a while, and said ‘No’.
“Instead, he asked for the right to fish that spot for the rest of his life, and for that right to stay in his family forever. My take on this fishy tale is that we should think about the world we want our children to grow up in.
“Sturgeon – alongside all other wildlife species – are part of a future where nature and people thrive together, so let’s do all we can to bring them back.”
Top image: Linnéa Jägrud is “nervous, relieved and elated” as she releases an Atlantic sturgeon into the Göta River. Credit: Jon A Juárez
About the photographer
With a degree in biology and an interest in conservation, Jon A Juárez is a member of the German Society for Nature Photography. See more of his work at jonjuarez.photo.
