The bigmouth buffalo is a fish species indigenous to Minnesota, celebrated for its exceptional lifespan. Researchers aimed to uncover more details about this species, particularly regarding its migration, spawning patterns, and the survival rates of its young into maturity.
A new investigation conducted in one of Minnesota’s most untouched breeding habitats has revealed a surprising 50-year gap between successful breeding occurrences, and this number appears to be increasing.
This finding comes from recent research on the bigmouth buffalo (Ictiobus cyprinellus) conducted by the University of Minnesota Duluth (UMD) and published in Scientific Reports. The study was spearheaded by Alec Lackmann, PhD, a fish scientist and assistant professor of Mathematics and Statistics, along with Mark Clark, PhD, a Biology professor, both affiliated with the Swenson College of Science and Engineering at UMD.
The bigmouth buffalo is a species known for its longevity and native to Minnesota. Researchers sought to learn more about its migration, reproduction, and how frequently its young reach adulthood. Over a three-year period from 2021 to 2023, Lackmann and his team investigated leisure fishing practices (such as bowfishing and angling) and analyzed the migration of bigmouth buffalo around the Rice Lake National Wildlife Refuge close to McGregor, Minnesota.
Key findings from the study include:
- Identification of one of the oldest known vertebrate populations, with a median age of 79 years as of 2024.
- A gap exceeding 60 years since the last significant recruitment event in this population, highlighting the vulnerability of bigmouth buffalo in Minnesota.
- Confirmation that the fish are successfully migrating and reproducing, but there is a high mortality rate among the young, likely due to predation.
- Identification of the management challenges posed by bigmouth buffalo, including inconsistent spawning periods each year and the necessity to protect mature adults as they contribute significantly to reproduction.
Lackmann and Clark have previously researched buffalofishes, and their 2019 study extended the perceived maximum age of bigmouth buffalo from approximately 25 years to over 100 years using enhanced aging methods. Their subsequent research in North Dakota (2021) and Canada (2023) explored environmental conditions affecting their intermittent success in recruitment. In their 2023 paper published in Scientific Reports, they found the second genus of animals (buffalofishes) known to possess lifespans exceeding 100 years.
“No one has really investigated the spawning patterns of bigmouth buffalo until now,” stated Lackmann.
Throughout the Rice Lake study, he and his team analyzed close to 400 adult fish, measuring their length and weight, assessing whether they had spawned, examining physical characteristics, and determining their age. The research demonstrated a correlation between water management practices implemented in 1953 and a diminished likelihood of future generations, revealing that out of the 390 fish studied, only one hatched after 1971. Although bigmouth buffalo were observed reproducing, by late summer, the young fish were notably absent, likely predated by northern pike and other predators.
“More than 95 percent of the current population hatched before the 1960s,” noted Lackmann. Given this substantial gap, it’s remarkable that the buffalofish have persisted across generations. However, as Lackmann points out, this reflects the incredible characteristics of these fish. “This species evolved to have an extended lifespan to survive the lengthy gaps that can naturally arise.”
During the 1970s, bigmouth buffalo populations were reported to be declining across Canada, Minnesota, and North Dakota, leading to their protection in Canada. In the US, population declines are worsened by inefficient recreational bowfishing, insufficient fisheries management, and a general lack of awareness.
Lackmann emphasizes the necessity of applying fundamental fisheries management principles to safeguard bigmouth buffalo and other native species. While he recognizes that initiatives like the “No Junk Fish Bill,” enacted this spring, are being pursued to protect native fish in Minnesota, he insists that much more needs to be done. For instance, unrestricted fishing of bigmouth buffalo is still permitted in Minnesota as of September 2024.
“This system has endured a 50-year recruitment failure for bigmouth buffalo, even though they continue to migrate and spawn yearly. As far as we know, there’s nothing like this in the animal kingdom where a species has gone so long without successfully producing another generation,” said Lackmann. “When combined with the current unchecked exploitation, particularly in the past decade due to the rise of bowfishing, there is serious concern for the long-term survival of this species.”
Various evidence indicates that the long-lived bigmouth buffalo is at risk, necessitating a precautionary stance and the closure of the unlimited and unregulated fishing of this species, as stated by Lackmann and his team.
In addition to Lackmann and Clark from the University of Minnesota Duluth, this study involved collaboration with the Aitkin County Soil and Water Conservation District, the United States Fish and Wildlife Service, and North Dakota State University.
