Nearly half-century-old fish caught and released during fish surveys on Lake Superior
BAYFIELD, Wis. — State fish biologists conducting spawning surveys on Lake Superior hauled in a lake trout earlier this month that hatched when Richard Nixon was president.
The fish was originally caught and released during the Wisconsin DNR‘s spawning assessments for lake trout in 1981. It was caught and released again Nov. 2 in the same fish refuge, the Gull Island Shoal of Lake Superior.
“We often think of a fish’s life span being relatively short, maybe 10 years,” says Terry Margenau, DNR fisheries supervisor. “But lake trout are slow growing and have a longevity that will rival that of the ancient sturgeon.”
To help assess the condition of lake trout on Lake Superior, the DNR has been conducting spawning lake trout assessments since 1951. Part of the assessment includes tagging the fish caught and releasing them so biologists can monitor their growth and movement in future years.
The fish caught Nov. 2 had first been tagged in 1981 when it was 27.3 inches during a DNR spawning assessment on Gull Island Shoal of Lake Superior. The same fish was handled again in 2017 during the same spawning assessment and measured 35.5 inches, Ray says.
“This lake trout grew about 8 inches over 36 years, or less than a quarter inch per year,” he says. “So very slow growing. Its age is also interesting.
“Considering this fish was likely 10 to 12 years old when it was tagged in 1981, this fall it would have been at least 46 years old.”
The same fish would be caught by DNR seven more times during surveys, Ray says.
In all of those instances, the fish was captured in the Gull Island Refuge.
“The spawning site fidelity of this fish, and many others we have sampled, emphasizes the importance of the refuges and the protection it affords the spawning stock of lake trout,” he said.
Anglers who catch a tagged lake trout and intend to release the fish are asked by the DNR to write down the tag number and contact the Bayfield DNR office to get the capture history.