Most anglers will brag about catching a wily old fish, but the one Michigan Department of Natural Resources researchers pulled from Lake Superior during a September 2023 survey is old enough to put most of those stories to shame. The team named the lake trout “Mary Catherine,” and lab analysis later revealed she was 62 years old, making her the oldest lake trout ever recorded in the Great Lakes.
Mary Catherine weighed 4.62 pounds and measured just under 25 inches long, according to an MDNR press release. Those stats might not seem impressive compared with the Michigan state record of 61.5 pounds, caught from the same lake in 1997, but size isn’t what makes her remarkable. She belongs to the “humper” subspecies, known for slow growth and a diet heavy on invertebrates.
Researchers confirmed that Mary Catherine hatched in 1961 by counting growth rings on her otoliths, ear bones that record a fish’s life much like tree rings. That means she was just a tiny fry the same year John F. Kennedy was inaugurated, Motown signed Diana Ross and the Supremes, and 1,400 Cuban exiles landed in the Bay of Pigs. To put that in perspective, this fish was swimming in Lake Superior’s depths long before many of today’s anglers were even born.
Researchers caught her at Klondike Reef, a deep site in Lake Superior, using a specialized net during a routine survey designed to study different lake trout types. While surveys like this usually produce plenty of useful data, finding a fish that old is rare. Mary Catherine offers an unusual and valuable glimpse into the health of the lake.
The fish’s long life also underscores the success of one of the Great Lakes’ biggest conservation turnarounds. Lake trout populations once collapsed under the combined pressure of overfishing and predation by invasive sea lamprey. By the 1950s, the species was nearly gone from much of the region.
Lake trout recovery kicked off in the 1960s, right about the time Mary Catherine was hatching. At the time, sea lampreys were hammering the population. Aggressive restocking programs and lamprey control measures were implemented to help give the fish a fighting chance. Smart management kept the ball rolling and anglers slowly started seeing more trout on their lines. MDNR declared the species officially recovered on Lake Superior in 2024.
Mary Catherine’s survival is living proof of that success. This old fish lived through the years when her species was at its lowest. For biologists, it represents solid data showing that trout in Lake Superior are not only surviving but reaching full lifespans. For anglers, it is evidence that the lake is healthy enough to produce not just trophy fish, but to support fish through their entire lifespan, allowing them to reach a ripe old age.
