At 62 years old, a fish nicknamed “Mary Catherine” was swimming through Lake Superior during some big events. Mary Catherine is believed to be the oldest-known specimen of her species ever caught in the Great Lakes. Mary Catherine is a humper lake trout, a subspecies of trout that is usually found in offshore lake mounts in Lake Superior. Mary Catherine living such a long life in those conditions is a good sign for lake trout living in the largest of the Great Lakes and their ability to adapt. Lake trout in Lake Superior are believed to live about 25 to 30 years.