Fish hatched during WWI in Iowa and sent to Arizona by railcar are still alive—and they may have a lot to teach us about longevity
by Science Writer Kim Woolcock
Only ~35 animal species are known to have lifespans longer than 100 years, and most of them are unrelated. Only the genus Sebastes, ocean rockfishes, contains more than three long-lived species. Now a citizen–science collaboration has identified three species of buffalofishes, all in the genus Ictiobus, thatlive to be over 100 years old. The open-access paper “Centenarian Lifespans of Three Freshwater Fish Species in Arizona Reveal the Exceptional Longevity of the Buffalofishes (Ictiobus)” by Lackmann et al. was published in Scientific Reports on October 20, 2023.
Buffalofishes are native to North America, with three species (bigmouth buffalo I. cyprinellus, smallmouth buffalo I. bubalus, and black buffalo I. niger) endemic to areas near the Mississippi or Hudson Bay. The fleshylip buffalo I. labiosus is native to Mexico, and the usumacinta buffalo I. meridionalis is native to Mexico and Guatemala. Buffalofish are large (up to 36 kg/80 lbs) and in the late 19th and early 20th centuries they were prized for eating. In the early part of the 20th century, the Bureau of Fisheries began a buffalofish hatchery program, and after completion of the Roosevelt Dam in 1911, the Bureau sent 420 fingerling, yearling, and adult buffalofish hatched at Fairport Biological Station in Iowa by rail to stock Roosevelt Lake (Arizona), where they were commercially fished for 30 years.
In the following decade, several more dams were constructed in the area, and buffalofish made their way into Apache Lake (Arizona), where they remained largely undisturbed until recently. Buffalofish had always been considered very difficult to catch with rod and line, and Apache Lake is in a steep area with primitive roads and is tricky to access.
Then, recreational anglers figured out how to catch buffalofish in Apache Lake. They use a small, micro-barbed hook, with bait (often fake corn) wrapped with pack bait, usually oats and breadcrumbs with bits of cladocerans, chironomids, and food oil. Cast about 10–100 m/33—330 ft from shore, the pack bait creates a food plume that attracts buffalofish; rod alarms signal the anglers when a fish bites.
When anglers started catching buffalofish, they became curious about the black and orange spots on their sides. While researching the spots, they found a 2019 study by Lackmann et al. revealing that bigmouth buffalo can live to be 112 years old, much older than the previous estimate of 26 years. The new age estimate was based on study of the fishes’ otoliths, or ear stones. Otoliths gain a new layer of bone each year; if they are thin-sectioned, an experienced person can count their rings, just as one would count the rings of a tree, to determine the fish’s age. The anglers invited Lackmann and his lab out to Apache Lake to catch and study fish, and thus began a fruitful citizen–science collaboration.
Lackmann’s team made two trips to Apache Lake, and the anglers donated the 23 fish caught and kept during those expeditions. The fish were weighed and photographed, and their otoliths were examined to determine their age. Anglers also began documenting all buffalofish catches, photographing and weighing the fish before releasing them, and logging 199 fish from 2018 to 2023.
The collaborative team compiled a database of 222 fish captures. All but one fish had the black and/or orange spots that had precipitated the collaboration, and using image analysis the researchers found that they could identify individual fish and thus make note of recaptures (31 individuals were recaptured between two and six times), noting changes in a fish’s size over time.
Age analysis of the 23 donated fish showed that except for one fish, aged 11, all other fish were between 85 to 108 years old, indicating an extremely long-lived population. Most of the fish in Apache Lake are estimated to be more than a century old, and many were likely hatched at the Iowa hatchery during WWI. Although the captured fish appeared mature and capable of spawning, the fact that only one young fish was caught raises the concern that buffalofish are not spawning often; further investigation is needed.
Studying buffalofish genetics and physiology might teach us about longevity. So far, scientists have identified key physiological differences, including negligible senescence and physiological improvements at 100 years, in buffalofishes. Other species are being studied, too. Ocean rockfishes, which can live to be over 200 years old, are being examined for longevity-related genes. A 2021 study of rockfish found evidence of positive selection on DNA repair genes and life span variation associated with differences in insulin regulation genes. Conserving and studying the long-lived buffalofish population in Apache Lake may yield important clues to how animal lineages can evolve to have very long lifespans, and the physiological and genetic mechanisms that allow them to do so.