Alec Lackmann has been fascinated by bigmouth buffalo (Ictiobus cyprinellus) since the sixth grade, when he learned about how ecosystems work. The idea of an entire community of different species interacting with each other intrigued him, and he’s never been able to understand why most of us get so excited about some members of the community and not about others.
In case you’ve never heard of a bigmouth buffalo, it’s an ancient fish that evolved 50 million years ago, a sucker that lives in shallow lakes and slow-moving parts of rivers. Endemic to the Mississippi River and Hudson Bay drainages, it’s a filter-feeder that most fisheries managers lump together with other suckers like white sucker and redhorse, under the derogatory name “rough fish.”
It wasn’t until Lackmann finished his dissertation at North Dakota State University (on tundra pond ecology) that he began to refine the traditional method of the aging of fish. Scientists use otoliths, part of the inner ear of fishes, to determine the age of the fish. The otolith is a rock-like structure that allows fish to hear and sense vibrations in the water and provides a sense of balance. Three pairs of otoliths in each fish grow by adding layers of material almost like a tree.
Lackmann says most “rough fish” have been ignored by wildlife managers and researchers. “I could only find one study previous to 2019 that looked at otoliths in bigmouth buffalo,” he says. “The authors had looked at two of the six otoliths in each fish, the pair known as the lapillus.” The lapillus otolith is relatively easy to dissect, but Lackmann taught himself to dissect the other two types, including the asteriscus, “which is really valuable for determining age in this species.” It was pure curiosity that pushed him. “There was nothing in the literature,” he says. “I was just following my curiosity and interest.”
He was able to cross-check the results of his method through bomb radio-carbon dating. As a grad student he had a chance to use a mass spectrometer at the Woods Hole Oceanographic Institution in Massachusetts to perform a bomb radiocarbon dating test. The atomic bomb tests of the 1950s and 1960s produced a spike of carbon-14 in the atmosphere, enabling researchers to attach a very specific date to an animal that lived during that time. It’s used to verify estimates based on otoliths. Bomb radiocarbon dating confirmed that Lackmann’s age counts were accurate.
He realized—to the astonishment of other researchers—that many of these fish were very, very old. He found one bigmouth buffalo that was 112 years old, more than four times older than previously thought for maximum age.
Other species in the same subfamily, Lackmann and his colleagues found, can live more than 40 years. “Quillback don’t even have very large bodies, so they don’t get more than three-to-four pounds at maturity, yet we’re finding individuals more than 40 years old,” he says. He found another species in a different group of fishes, the bowfin, can live more than 30 years, approximately three times older than generally thought in the wild.
Not only that, these graybeards have interesting life histories.
“These fish are playing the long game,” says Lackmann. “Take for example the bigmouth buffalo: their eggs are vulnerable to predators and their young are like baitfish, but if they can make it to about five or six years old, it’s as if they’re immortal; nothing can eat them because they’re so big.” They need this long period of adulthood because they experience long gaps in reproductive success, a tendency which is related to environmental conditions. In some of the areas Lackmann’s team studied, as much as 90-percent of the fish were more than 80 years old. “Their long lives allow them to bridge unfavorable conditions in the environment,” he says. “Eventually there’ll come a year when it’s a great time to reproduce, and they’ll have a boom that can sustain the population for another 100 years.” Unfortunately, this lifestyle makes the fish extremely vulnerable to overfishing and population collapse. Among other human-caused challenges, when people built dams in the 1930s, these fish (among many others) lost the ability to swim upriver to spawn. In fact, bigmouth buffalo are declining across the northern extent of their range, including in Minnesota, North Dakota, Pennsylvania, and Canada. This decline is likely happening in other areas, but they have been so neglected that they have not even been assessed across much of their range.
These fish were living quietly for years—millions of years—helping keep the water clean and contributing to the natural balance of aquatic ecosystems in North America. They arose roughly at the same time as whales were leaving land for the ocean.
In the last fifteen years or so, they have met with a new challenge: bowfishing.
Bowfishers know the difference—visually—between buffalofish and invasive carp. Carp are yellowish, and up close, you can see that carp scales are separated by dark junctions, while the buffalofish has a smooth, uniform brownish sheen. But because fisheries managers lump native “rough fish” with invasive carp, you can see why bowhunters enthusiastically target natives as well as carp.
Bowfishing has grown in popularity, with tournaments all over the state and an active group promoting the sport. Some observers have raised concerns about the fate of the fish, as some are not eaten and few can be released.
In 2010 the Minnesota legislature legalized nighttime bowfishing, which made it much easier for hunters. At night the water is calmer, powerful lights can shine into the water, and the fish are stunned by the lights.
But, as happens so often in life, accurate understanding and management need to catch up with recreation. In a 2020 study, researchers found that only nine of the U.S. states had bowfishing education programs and none had articulated management goals or plans specific to the sport. They point out that, contrary to terrestrial and avian species, female fish tend to be larger than males, and “the result is selective depletion of large, older, mature females and evolutionarily disruptive truncation of life histories.” Add to this the impracticality of catch-and-release with bowfishing, and the authors suggest it is time for more study and regulation.
As every species does, these fish play an important role in their ecosystems. Some of them serve as hosts for the larvae of parasitic freshwater mussels. The larvae attach themselves to certain species of fish; not all can serve as hosts. Some “rough fish” are known to perform this function, but research is just beginning on this question.
As filter feeders, they are also thought to improve water quality by consuming and processing contaminants. Filter feeders are important players in food webs, controlling primary production and contributing to ecosystem stability.
These fishes’ evolution and behavior provide protections that have allowed them to survive millions of years and at least one great extinction. For example, the bowfin (dogfish, Amia calva) can survive in oxygen-depleted waters by gulping air at the surface. Bowfin males aggressively protect their spawn for a month or so, until they are about four inches long. When the young are old enough to form a school and leave the nest, their male parent slowly circles them to keep them together. They are also capable of fasting for very long periods of time.
In a newly-published study of fish from the Qu’Appel River system in western Canada, Lackmann and his colleagues documented bigmouth buffalo more than 125 years old.
Researchers observe “year classes” in fish populations: years when successful spawning and survival of young occur. By determining the ages of the current population, Lackmann and his colleagues documented that successful reproductive years occurred only 13 times since that 127-year-old fish hatched. The most recent, 1997, was a year in which the water was high in spring, and the level diminished gradually, allowing “progeny the time to hatch, develop into mobile fry, and then swim out of nursery habitat into juvenile habitat,” the study found.
Lackmann concludes that bigmouth buffalo can only add to their population within a “narrow range of water-level fluctuations that may rarely occur,” and that if we humans want to keep living alongside these ancient fish, we need to pay attention to their unusual lifestyle and adjust our own behaviors to accommodate them.
There’s news about Minnesota’s approach to native “rough” fish.
In September, the Minnesota Division of the Izaak Walton League and other conservation groups petitioned the Minnesota DNR to write new rules to protect native “rough” fish. After discussion with DNR officials, the groups withdrew their petition and signed an agreement to work together with the agency to try to meet their goals. Minnesota Izaak Walton League spokesperson Tyler Winter said the cooperative approach is better because more than rulemaking will be needed. “We can advance strategies for communication, data collection, regulations and legislative reforms. It will take action in all these areas (and more) to manage native fish as a public trust,” Winter said. DNR Director of Fish and Wildlife Dave Olfelt said he’s excited to work together on improved protection for these populations. “We will dive into current regulatory structure and understand what levers we (already) have to pull, and then talk about how we propose to put those remedies in place.” The agreement is to work together for a year.
All photos courtesy Alec Lackmann.