Researchers say that a lake trout recently captured in Lake Superior is believed to be the oldest-known specimen of its species ever caught in the Great Lakes, estimated to be 62 years old.
The fish was collected at Klondike Reef in autumn 2023 by researchers with the Michigan Department of Natural Resources, along with multiple universities and the U.S. Fish and Wildlife Service.
According to the DNR, one of the fish specimens collected may not have tipped any physical records scales, weighing in under 5 pounds and measuring just over 2 feet in length, but it certainly qualifies as the oldest fish ever documented among the five Great Lakes.
Michigan Department of Natural Resources 
The fish is believed to have hatched in 1961, long before a man walked on the moon, long before the first known test-tube baby, and even before President John F. Kennedy was assassinated. DNR officials said, with some whimsical logic, that if the fish were to have gone through human schooling, it would have graduated the same year as former president Barack Obama and Princess Diana of Wales.
A typical lake trout in Lake Superior is thought to be roughly 25 to 30 years old. Prior to this new discovery, the oldest trout reported in the lake was estimated to have reached 42 years of age.
Researchers determined the age of the fish by counting the number of “rings” visible on the fish’s otolith, or “ear stone,” which grows through the years of a fish’s life.
Michigan Department of Natural Resources 
The Michigan DNR said that staffers have taken to calling the fish “Mary Catherine,” as Mary was among the most common names given to baby girls the year the trout was born.
Officials say that they take samples of fish to track population health, and the discovery of Mary Catherine indicates that lake trout are doing well in Lake Superior.
