Some of the lake sturgeon swimming around in the Great Lakes today may have been alive when Samuel de Champlain first reached Lake Huron more than four centuries ago.
New research suggests these ancient-looking, armoured fish may live far longer than scientists previously thought — in some cases, more than 400 years.
But despite their extraordinary longevity, lake sturgeon — which can weigh up to 180 kilograms and grow up to two metres long — have barely survived us. In Ontario, lake sturgeon are listed as a species at risk, and endangered in the Great Lakes specifically.
Overfishing and destruction of their spawning habitat wiped out an estimated 99 per cent of the lake sturgeon’s historic population. More than a century later, populations in parts of the Great Lakes still rely on human beings raising and releasing young fish to help them recover.
The new study uses more than four decades of data from lake sturgeon caught and recaptured across the Great Lakes, suggesting recovery could be a much longer project than scientists anticipated.
A new way to count sturgeon birthdays
“We’re pretty comfortable saying that there are potentially 400-year-old lake sturgeon swimming around,” said Ed Baker, a fisheries scientist with the Michigan Department of Natural Resources who led the study.
Traditional estimates suggest lake sturgeon can live for as long as 150 years. But figuring out how many birthdays a sturgeon has had isn’t as easy as counting candles on a cake.
University of Windsor biologist Trevor Pitcher introduces us to a young lake sturgeon and explains what makes these ancient fish so remarkable — and so difficult to age.
Scientists have typically estimated a sturgeon’s age by counting annual growth rings in a cross-section of its fin ray. But the older a sturgeon gets, the more slowly it grows — and the harder those rings become to distinguish.
Instead of counting growth rings, Baker and his colleagues used 44 years of capture data to calculate how much individual sturgeon grew between one capture and the next — then modelled how long it would take them to reach adult size.
In one remarkable case, a male sturgeon measured 117 centimetres when researchers caught the fish in 1990. When the same fish was caught again 34 years later, it had grown just seven centimetres, or about 0.21 centimetres per year.
When researchers used those real-world growth rates to calculate how long it would take a fish to reach full size, some of the resulting ages stretched into centuries.
“It’s a completely unexpected result,” Baker said. “But it’s one that’s supported by the data, for sure.”
The very long game of saving sturgeon
For Trevor Pitcher, a University of Windsor biologist who has spent years trying to rebuild lake sturgeon populations, the finding raises a much bigger question: What does it mean to conserve an animal whose lifespan may be measured in centuries?
“I think it changes everything,” he said. “Assuming they do live, let’s say 200 to 400 years, we need to reframe the way we do conservation.”
Canada’s existing conservation plan is a century long, Pitcher said, with the expectation the work will outlast the individuals who started it. If the new longevity estimates hold up, the assumptions behind that plan may have to change, he said.
“We would have to readjust some of our plans about restoration, and some of the habitat work would certainly be different.”
Pitcher said sturgeon eat large numbers of invasive quagga mussels and gobies, helping hold those populations down. Because historic overfishing and habitat destruction by humans reduced sturgeon to roughly one per cent of their former population, he said, “we kind of shot ourselves twice in the foot.”
“When you take out a key species like sturgeon, it changes everything in the food web.”
Pitcher’s work is already extending beyond his own lab. His team is helping train people in Georgian Bay and Walpole Island First Nation to raise lake sturgeon themselves — spreading the expertise needed to rebuild populations around the Great Lakes.
A spiritual connection that runs deep
For Perry McLeod-Shabogesic, an elder and knowledge keeper from Nipissing First Nation, about 40 kilometres west of North Bay, Ont., the importance of lake sturgeon extends far beyond their role in the ecosystem.
“Because of their longevity, they were considered like a grandfather fish.”
A fish that can live for centuries experiences and witnesses things across generations, he said, and it’s the reason sturgeon are regarded as elders in Anishinaabe tradition.
“They’re seen as elders — fish elders, if you will,” he said.
Their appearance adds to that sense of age. Lake sturgeon belong to a lineage of fish that stretches back more than 150 million years — long before humans appeared.
It was only relatively recently that their numbers collapsed, as habitat destruction and commercial fishing nearly wiped them out across the Great Lakes.
Lake Nipissing once teemed with sturgeon. McLeod-Shabogesic remembers older fishermen describing spring spawning runs, when the fish crowded the Sturgeon and French rivers so thickly that their backs broke the surface.
“You could walk across the river, they were so thick,” he said.
‘Duh’
For McLeod-Shabogesic, the unusual traits also place the fish in another category; he describes sturgeon as beings that live “in between” — neither like other fish nor anything else in the lake.
In Anishinaabe teachings, he said, things do not always fall on one side or the other; between male and female is two-spirit, between hot and cold, there is warm. Sturgeon, he said, occupy a similar space.
That idea appears in an old Nipissing story McLeod-Shabogesic learned from his father. A family staying on the Manitou Islands caught and ate a mysterious black fish. By the next morning, they had transformed into serpent-like beings and disappeared beneath the ice.
The story, he said, speaks to the sturgeon’s place in between worlds, and to its power and medicine.
“They weren’t a fish completely and they weren’t a snake completely. And then their age — they were different from the other fish.”
So when McLeod-Shabogesic heard scientists now believe lake sturgeon may live for centuries, he wasn’t surprised. “Duh,” he said, laughing.
“It validates things to a certain degree,” he said. “These are things that we already knew that our teachers and my ancestors — my grandparents and those fishermen that have fished this lake for a long time — they all knew these things already.”
