The bigmouth buffalo (Ictiobus cyprinellus) may be the world’s longest-lived freshwater fish, but in the pristine spawning grounds of Minnesota’s Rice Lake, there has not been a new generation for over 50 years, a study in Scientific Reports reveals.
Alec Lackmann from the University of Minnesota and colleagues analysed bigmouth buffalo fish in and around Minnesota’s Rice Lake National Wildlife Refuge between 2021 and 2023.
Despite adult fish returning to their spawning ground every May, mating, and laying eggs that hatch, by late summer, all the young fish are gone. The only bigmouth buffalo that remain are old ones; 99.7% of the fish sampled and aged – 389 out of 390 fish – were more than 50 years old.
The finding is all the more perplexing when you consider just how hardy these fish are. Lackmann has previously shown, not just that they can live for over 100 years, but that they remain remarkably fit in their old age. Their cells show little sign of age-related damage, and their immune systems appear robust.
This is of no help, however, to the hatchlings. Lackmann believes the reason that new generations are failing to survive is because they are being gobbled up by predators, such as the northern pike, which also spawns in the lake.
“There is 50-year recruitment failure,” says Lackmann. "When you couple that with the current, unlimited and unregulated nature of their exploitation that's been increasing, especially in the past 10 years with the rise of bowfishing, there is extreme concern for the long-term sustainability of this species."
Main image: bigmouth buffalo fish/Alec Lackmann, University of Minnesota
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