When the Declaration of Independence was signed in 1776, some lake sturgeon swimming through the Great Lakes today may have already been alive.

That’s the surprising conclusion of a Michigan Department of Natural Resources and Michigan State University study suggesting scientists have significantly underestimated the lifespan of one of North America’s oldest freshwater fish.

Using decades of capture-and-recapture records from five Great Lakes populations, researchers found that in some populations many lake sturgeon may routinely live well beyond 200 years, with some approaching 300 years.

“Scientists have long recognized that lake sturgeon are among North America’s longest-lived freshwater fish,” said Scott Colborne, assistant professor in Michigan State University’s Department of Fisheries and Wildlife. “But the new study suggests they may live far longer than previously appreciated.

“These fish are a living connection to history,” he said.

For decades, scientists estimated the age of lake sturgeon by counting growth rings in fin spines. But because those rings become increasingly difficult to interpret in older fish, researchers suspected they were underestimating the age of the oldest individuals.

To test that idea, Colborne and his colleagues turned to one of the largest long-term datasets ever assembled for lake sturgeon. By analyzing growth records from tagged fish that had been measured repeatedly over many years, they developed a more accurate picture of how slowly these ancient fish continue growing throughout their lives. The team used mathematical models similar to those previously applied to estimate the remarkable lifespan of Greenland sharks.

The findings have important implications for conservation.

Lake sturgeon mature slowly, reproduce infrequently and can take decades to replace themselves. Better estimates of how long they live help scientists more accurately understand survival, population recovery and the long-term effects of harvest and habitat restoration.

The research also highlights the value of long-term conservation. The discovery was only possible because university researchers, tribal nations and state partners spent decades protecting, tagging and monitoring lake sturgeon across the Great Lakes.

“It really highlights the importance of long-term conservation and monitoring,” Colborne said. “Without people collecting these data over decades, we couldn’t answer questions like this.”

One conversation during the project particularly resonated with Colborne. While discussing the research with a tribal community member, he learned that some Indigenous communities had long believed lake sturgeon could live as long as 400 years.

“That was one of those goosebump moments,” Colborne said. “Here we were using modern analytical approaches, and they were pointing us toward something that Indigenous communities had long understood — that these fish live incredibly long lives.”

Although the study suggests many lake sturgeon live well beyond 200 years, researchers say more work is needed to understand the biology behind such extraordinary longevity. The findings may also prompt scientists to revisit how they estimate the age of other long-lived fish species.

Although the study raises new questions about how scientists estimate the age of long-lived fishes, it also reinforces something Colborne has come to appreciate after years of studying lake sturgeon.

“Because of their life history, sturgeon are very resilient and adaptable animals,” he said. “If we give them the opportunity to survive, they’ll figure it out. There’s a reason these fish have been around for millions of years.”

The study was funded by a State Wildlife Grant awarded through the Michigan Department of Natural Resources.