DETROIT LAKES -- While he was in the process of completing his doctoral dissertation on the tundra pond ecology in High Arctic, Alaska, Alec Lackmann began a side project a little closer to his home in Detroit Lakes.
But what the North Dakota State University graduate student and his colleagues discovered in an Otter Tail County lake would shock researchers and make headlines from the Minneapolis Star Tribune to National Geographic .
As part of his research into previously overlooked species of fish, Lackmann came across a variety of freshwater fish native to Minnesota that is commonly known as the bigmouth buffalo.
"I became interested in researching this species out of curiosity," Lackmann said. "I am generally interested in ichthyology (i.e. the study of different fish species). I am naturally interested in bigmouth buffalo because they are such a mysterious species, with so little study regarding their general biology."
When they age tested some fish that had been taken from the waters of west-central Minnesota, Lackmann and his colleagues determined that five of them were more than 100 years old — including one 112-year-old female that came from Crystal Lake, near Pelican Rapids.
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To determine the age of the fish, Lackmann and his fellow researchers took samples from their otoliths — ringed growths behind their brains, each with a different shape, that help the fish with hearing and balance.
"Otoliths are the only structures found in fish that never stop growing," Lackmann said. Similar to the way tree rings grow, a new ring layer forms on the otolith each year, which means they can be counted to determine the age of the fish.
"The most accurate way to age otolith-bearing fish species is to thin-section the otoliths," Lackmann said. Some fish species, like many sharks, do not have otoliths, he added.
What he and his fellow researchers found was that over 80% of the fish from the Pelican River Watershed had been around for 80 years or more. But as initially skeptical as the members of Lackmann's research team were regarding their findings, the reaction from the general public was even more so, as the species was previously considered to live a maximum of 26 years.
In collaboration with the University of Hawaii and Woods Hole Oceanographic Institution, they decided to test the validity of their findings with the well established science of bomb radiocarbon dating. The results confirmed their findings.
"The ages determined from the thin-sectioned otoliths were validated," Lackmann said.
The fish taken from Otter Tail County was verified to be 112 years old — which made it the oldest age-validated freshwater fish ever discovered.
So they took their findings and put together a research paper that was published in the nature research journal, "Communications Biology," in May of this year. That research paper caught the attention of news media.
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Prior to Lackmann's study, the most thorough report that had been done was a paper published in 1963.
"A lot has changed in fisheries since that time," Lackmann said. "I also did not understand why this species is neglected as a 'rough fish,' and erroneously called 'carp' (or alternatively, 'buffalo carp') in so much of the U.S."
"They are not carp," he said bluntly. "They may superficially resemble each other, but they have many differences."
Bighead and silver carp, which both come from Asia, and the common carp, which is native to both Europe and Asia, are all classified as invasive species in this region; the bigmouth buffalo, on the other hand, are native to North America, have ties to Native American culture, have been a valued food-fish for centuries, and have been a protected species in Canada since the 1980s, Lackmann said.
In addition, he said, these buffalo fish compete directly against some of the worst invasive species found in Minnesota lakes and rivers, and their populations have been documented as declining in the northern extent of their native range — specifically, in Canada, North Dakota and Minnesota — since in the 1970s.
Lackmann is hoping that all this attention will raise awareness of the value of the Bigmouth Buffalo to the region, both ecologically and economically. Anyone who would like to find out more about this fish, or provide funds for further research, is welcome to contact either Lackmann ( alec.lackmann@ndsu.edu ) or any of the co-authors on the research paper referenced above.
