(WXYZ) — Often called the living dinosaur of the Great Lakes, lake sturgeon are known to live more than 100 years. However, a new study found that they may live much longer.
The Michigan Department of Natural Resources, Michigan State University, Michigan Technological University and the Wisconsin Department of Natural Resources published a new study that found some lake sturgeon may live more than twice the previously-known lifespan.
The DNR published an article called "Long live the sturgeon," published by DNR Marquette Fisheries Research Station Manager Dr. Edward Baker, and DNR communications specialist Edward Baker, where they discuss the study's findings.
According to the DNR, fish age can be estimated by several structures, including fin spines or otoliths (an ear bone). Those, like trees, show annual growth rings. The oldest lake trout discovered in the Great lakes was estimated to be 62 years old by counting the growth rings in its otolith.
However, the lake sturgeon grow slowly and live for a long time, so using growth rings can be difficult because the rings can be numerous, thin and close together. Fish also continue to grow throughout their lives.
Researchers looked at five populations of Great Lakes lake sturgeon — Black Lake, Michigan (Cheboygan and Presque Isle counties); Sturgeon River, Michigan (Baraga County); Menominee River, Michigan/Wisconsin; St. Clair River (St. Clair County) and Lake Winnebago, Wisconsin.
They would capture the fish, measure them, determine the sex, mark the fish with a tag and release them. In future years, they would survey again, capture and tag sturgeon, but also re-capture sturgdon and measure their growth.
"With this information, we could look at how much fish grew between the time we first captured them and the subsequent recaptures. This was done over a period of 44 years, giving us ample opportunity to recapture sturgeon we’d measured before, some many years later," the authors said.
They then used the data to estimate lake sturgeon longevity by asking “If a lake sturgeon grows X centimeters per year, then how many years does it take for a lake sturgeon to get to a particular size?”
Using those equations, they estimated expected longevity for an approximately 63-inch male and 71-inch female sturgeon across the five populations.
According to the DNR, estimated longevity ranged from 90 to 279 years for males and from 99 to 427 years for females.
"That’s up to 277 years older than the oldest lake sturgeon previously recorded! It’s also nearly as long a lifespan as the longest-lived vertebrate on Earth, the Greenland shark, whose longevity has been estimated at 272 to 512 years," the article reads.
"When I began studying lake sturgeon in the late 1980s, I never thought I'd live to see their success and persistence after being listed as threatened,” said Nancy Auer, emeritus research professor of biological sciences at Michigan Technological University. “Let alone actually handle fish much older than I was — or am now, 30 years later — and that will be here after I am gone.”
