At 62 years old, a fish nicknamed “Mary Catherine” was swimming through Lake Superior during some big events. The lake trout (Salvelinus namaycush) was born when President John F. Kennedy was in office, when the “gales of November came early” sinking the SS Edmund Fitzgerald, and lived through 15 Summer Olympics. Mary Catherine is believed to be the oldest-known specimen of her species ever caught in the Great Lakes.
The name “Mary Catherine” is an homage to her birth year. Mary was the most popular name for baby girls in 1961.
Determining the age of a fish is similar to how we determine the age of a tree. Scientists use a structure inside the ear called the otolith, or ear stone. The ear stone grows throughout the years of a fish’s life, so scientists can count the rings to identify its age.
“Otoliths are used to assess the age of many other species of fish,” the Michigan DNR wrote in a social media post. “They tend to be used for long-lived fishes such as lake trout, lake whitefish and cisco, whereas for shorter lived fishes, fin spines and scales are used to count annual rings for species such as walleye, yellow perch, steelhead, and salmon.”
According to the Michigan DNR, finding such an old fish indicates that the lake trout in Lake Superior are doing well.
