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Some Fish in the Great Lakes Might Be More Than 400 Years Old, a Study Suggests, Outliving Around 15 Generations of Humans
Lake sturgeon may be among the longest-living vertebrates, second only to Greenland sharks, according to recent research. However, scientists note that follow-up work is necessary to clarify the species’ lifespan
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In the early 17th century, a refined version of the first telescope spotted some moons of the planet Jupiter, which is up to 54 light-minutes away. Horse riding was the fastest mode of land transportation, and smallpox ran rampant. Now, 400 years later, we have spotted a galaxy that is 13.5 billion light-years away. The fastest crewed train in the world has touched a speed of 375 miles per hour. We’ve completely eradicated smallpox.
And some fish in the Great Lakes may have been alive this entire time.
Research published this year in the Journal of Fish Biology suggests lake sturgeon (Acipenser fulvescens) have remarkable life spans. The study concludes that males may live up to 435 years, possibly more, which is nearly three times the age of the previously known oldest lake sturgeon. Still, the authors note the need for further research to confirm the findings.
“All sturgeon species now need to be reassessed for their age because of this paper,” says ichthyologist Prosanta Chakrabarty from Louisiana State University, who was not involved in the research.
Lake sturgeon are cartilaginous fish whose ancestors existed among dinosaurs 200 million years ago. Today, they’re the largest fish in the Great Lakes, typically reaching four to six feet long and weighing 30 to 80 pounds. Their average life span, according to existing research, is 50 to 100 years. A 154-year-old sturgeon caught on the border of Minnesota and Canada in 1953 was previously considered the oldest ever.
But accurately estimating the life spans of wild fish isn’t easy. Each dark ring on a fish’s scales, or on the pectoral fin spines of non-scaly fish such as sturgeons, represents a year of the animal’s life. Counting these rings, or annuli, can estimate the ages of fast-growing and relatively young fish, says study co-author Edward Baker, a fisheries researcher at the Michigan Department of Natural Resources. However, in long-lived and slow-growing sturgeons, the annuli eventually begin to form close together and become indistinguishable—or they don’t form at all.
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For this study, Baker and his colleagues used a different aging technique. They analyzed data on thousands of lake sturgeon that they had collected, working with natural resource agencies and universities, from 1980 to 2024. They monitored sturgeon populations in five waterways around the Upper Great Lakes: Black Lake, the Sturgeon River, the Menominee River, the St. Clair River and Lake Winnebago.
Over those 44 years, they captured sturgeon, identified their sex, measured their length and injected tags just under their skin, then released the fish back into the water. If they ever caught a fish that had already been tagged, they would re-measure and re-release it, creating a record of the change in its size over time.
Baker explains that veterinarians use the same type of transponder tags to identify cats and dogs. They contain a 15-digit number unique to the fish and have a nearly 100 percent retention rate, which allowed scientists to reliably identify the sturgeon they encountered, even as long as 42 years after they had last been captured.
With this record, known as capture-mark-recapture data, Baker and his colleagues calculated the average annual growth rates for each waterway’s lake sturgeon population. To do so, they measured the difference between a sturgeon’s length when it was most recently recaptured and when it was first captured, then divided that number by the years in the interval between.
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Sturgeon growth rates vary, as females typically grow more than males, and food availability influences fish growth. For example, sturgeon in the Black River grew less than 40 percent as much per year as those in the St. Clair River. In their age calculations, the team took into account the growth rate differences between sturgeon sexes and populations and considered that annual growth rates decline in fish as they grow older.
They developed an equation to estimate how old a 5-foot-3-inch-long male sturgeon and 5-foot-11-inch female sturgeon would be—the approximate maximum lengths of lake sturgeon across the populations—to predict the longevity of these fish.
Male sturgeon of that size, they found, would have a median age range of 87 to 215 years, and that range was 90 to 248 years for the females. However, some even larger fish in the data set had predicted median ages that went up to 435 and 292 years for males and females, respectively. “The age estimates for the largest fish we’ve caught from each population don’t necessarily represent the maximum age the fish could possibly reach,” Baker says. Larger and older males and females may be out there, he adds, and both sexes may reach similar maximum ages.
The study indicates that lake sturgeon can live nearly as long as marine-dwelling Greenland sharks, which are the longest-living vertebrates, and twice as long as rougheye rockfish, which are known to reach old ages. Lake sturgeon, per the new findings, may be the longest-living freshwater fish, although Baker notes that other sturgeon species might have similarly long lives.
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Spending time in torpor, which the fish do during winter, may prolong sturgeon longevity, the team suggests. In this state, animals reduce their physiological functions, like metabolism, heart rate, respiration rate and body temperature, to conserve energy, which increases their life span.
Chakrabarty says the method used to date the lake sturgeon has been in practice for a long time, but he calls it “a little more quaint than radiocarbon dating,” which is what scientists used to identify the Greenland shark’s life span a decade ago. The annual growth increments used in this study, meanwhile, are “kind of like measuring your kids’ height over time on a wall and predicting how tall they will be when they stop growing,” he adds.
The authors note in the paper that capture-mark-recapture data, like what was used for this study, predicted that Greenland sharks may be among the oldest fish before radiocarbon dating verified it. “We would like to try radiocarbon dating as a way to verify our age ranges and have reached out to the authors of the work done with the Greenland shark,” says Baker, noting that they are still awaiting a response.
Chakrabarty wonders what the maximum possible age of lake sturgeon could be, especially for old, giant individuals that lived around 80 years before fishing pressure stunted them. He remains cautious about the findings, however, and says he would consider labeling these sturgeon as the oldest vertebrates only after further testing is done.
“This should be just the start of more investigations and verification of age estimates for species like lake sturgeon,” says restoration ecologist Stephanie Ogren, vice president of science and education at the Grand Rapids Public Museum, who was not associated with the study. She says that funding for research into these threatened populations is necessary to manage them.
Did you know? The “lost” Syr Darya sturgeon
Worldwide, sturgeons are known as the most endangered species group on the planet. The Syr Darya sturgeon of Kazakhstan is considered a “lost” species by the nonprofit Re:wild, because it hasn’t been seen in more than 60 years and may be extinct. The Alabama sturgeon is feared to be extinct in the wild.
The research helps predict the growth and survival success of sturgeon, which could improve conservation efforts for this vulnerable species. In the late 19th century, 15 million lake sturgeon inhabited the Great Lakes. But their population has now been reduced to less than 1 percent of that estimate. Baker says that “unregulated harvest is what led to the decline in lake sturgeon populations in the early 1900s.”
Lake sturgeon take one of the longest times among freshwater fishes to attain sexual maturity. Females typically lay eggs after 20 to 25 years of age and may spawn once about every four to nine years, so their populations may decline rapidly and take a long time to recover. The new study indicates that the population turnover of this threatened species is slower than expected, as some sturgeon still lurking in these waters may have survived mass slaughtering and exploitative fishing centuries ago.
This calls for maintaining strict harvest limits for lake sturgeon and making adjustments to conservation plans that reflect their slow recovery, experts say. “We need to protect the species from harvest,” says Baker, or at least “be very restrictive in how much harvest is allowed, to give populations the opportunity to recover.”
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