A lake trout caught in assessment nets earlier this month by the Wisconsin Department of Natural Resources was likely hatched when Richard Nixon was president.
DNR officials estimate the age of the fish to be at least 46 years old. The fish was tagged and released.
The same lake trout was first caught and tagged in assessment nets in 1981, when it was thought to be 10 to 12 years old. Between 1981 and this month, the same fish was also caught six other times. Each time, it was caught in the Gull Island Refuge, a 130-square-mile fish refuge in the Apostle Islands.
“Lake trout are slow-growing and have a longevity that will rival that of the ancient sturgeon,” said Terry Margenau, DNR Lake Superior fisheries supervisor at Bayfield. “This fish is a prime example of that longevity and the important role fish refuges play in sustaining populations of these native fish.”
No fishing is allowed in the Gull Island and Devils Island fish refuges in the Apostle Islands.
The lake trout was 27.3 inches long when it was first caught and released in 1981. When it was caught on Nov. 2, it was 35.5 inches long.
“This lake trout grew about 8 inches over 36 years, or less than a quarter-inch per year,” said Brad Ray, DNR senior fisheries biologist at Bayfield.
The Gull Island Refuge was established in 1976, and the Devils Island Refuge in 1981. Creating the refuges was the primary factor in the recovery of Wisconsin’s lake trout population following their depletion from the sea-lamprey invasion and overharvest, Ray said.
Lake trout spawn on shoal areas within the Gull Island Refuge, Margenau said. Some of them eventually leave the refuge, while others tend to remain there.