Tracking the lifespan of a fish can be a slippery business.
A new study made a great discovery about the bigmouth buffalo, a freshwater bony fish that’s native to North America, and upended common knowledge about its longevity.
Previously, the oldest known bigmouth buffalo was only 26. But researchers recently dated a fish of the same species to 112 years old — more than four times what was originally thought to be the maximum age. This makes the bigmouth buffalo the oldest freshwater bony fish, a group of nearly 12,000 species, known thus far.
The bigmouth buffalo can reach 80 pounds, and has recently become a popular sport fish in the northern U.S. and southern Canada. Now they are the target of bowfishers, which shoot fish with bow-and-arrow, often at night with spotlights.
Fishing of the species is largely unregulated in the U.S. — 19 of the 22 states where the fish resides can harvest it in unlimited amounts — so researchers wanted to document its characteristics before their numbers dwindle.
In order to test the age, researchers removed thin slices of otolith — small calcified structures that help fish balance while they swim — from 386 bigmouth buffalo harvested by bowfishers. Researchers studied the growth rings on each slice.
The first test found fish that were estimated to be 80 to 90 years old, a surprise to researchers considering the original age estimate was anywhere from 10 to 26 years.
To validate their findings, researchers used bomb radiocarbon dating, which compares the amount of carbon-14 in the test subject to concentrations of carbon-14 released in the mid-1900s during atomic bomb testing, and found similar results. In fact, five bigmouth buffalo were estimated to be over 100, with one 22 pound fish breaking the record at 112 years old.
“She was actually on the smaller end of the mature individuals,” Alec Lackmann, the leader of the study said about the oldest fish.
Lackmann hopes knowing how long these fish can live will bring more awareness of the hardy species.