112-year-old fish has broken a longevity record

According to radiocarbon dating, when the bigmouth buffalo in question was born, World War I had not yet broken out.Monday, 5 August 2019

Scientists just added a large, sucker-mouthed fish to the growing list of centenarian animals that will likely outlive you and me.

A new study using bomb radiocarbon dating describes a bigmouth buffalo that lived to a whopping 112 years, crushing the previous known maximum age for the species—26—by more than fourfold.

That makes the bigmouth buffalo, which is native to North America and capable of reaching nearly 80 pounds, the oldest age-validated freshwater bony fish—a group that comprises roughly 12,000 species.

“A fish that lives over 100 years? That’s a big deal,” said Solomon David, assistant professor at Nicholls State University in Louisiana, who was not involved in the study.

In recent years, thanks to more advanced dating techniques, scientists have discovered many species of fish live longer than originally thought—the Greenland shark, for instance, can live past 270 years. Despite the age of fish being a basic aspect of their biology, we often know very little about a fish’s expected lifespan.

Carbon dating

Before the study authors even aged a single fish, they had a hunch that this particular species, which live mostly in the northern U.S. and southern Canada, lived longer than thought.

The team removed thin slices of otolith—small calcified structures that help fish balance while they swim—from 386 wild-caught bigmouth buffalo, most of which were harvested by bowfishers. The researchers then used a microscope to count the growth rings on each slice of otolith. Their first counts yielded estimates of fish that live more than 80 and 90 years old. 

When study leader Alec Lackmann first saw those numbers, he says his reaction was: “There’s no way!”

To validate these extraordinary age estimates, Lackmann, a graduate student at North Dakota State University, and colleagues turned to bomb radiocarbon dating, a well-established method that compares the amount of the isotope carbon-14 in animal tissue to concentrations of carbon-14 released in the mid-20th century during atomic bomb testing. The method has been used to age everything from human remains to sharks.

They then cross-checked their otolith results with bomb radiocarbon dating and found a match—validating the estimates of a lifespan between 80 and 90 years, according to the study, recently published in the journal Communications Biology.

In total, five bigmouth buffalo surpassed 100 years of age, but a 22-pound female caught near Pelican Rapids, Minnesota, became the 112-year-old record-setter. “She was actually on the smaller end of the mature individuals,” Lackmann notes.

Ageing population

The first 16 fish Lackmann aged were all over 80 years old, highlighting another surprising finding: Many of the fish were born prior to 1939, suggesting a reproductive failure spanning decades. The likely cause of this failure is dam construction, which impedes—or outright blocks—upstream movement to spawning grounds. 

Indeed, bigmouth buffalo are often called “trash fish,” because they’re not usually eaten and are erroneously lumped in with invasive U.S. species like common carp. But Lackmann argues “we should move away from that term, because it maligns far too many native species.”

David agrees, saying that it “automatically detracts value from the organism itself,” which, in the case of the bigmouth buffalo, has an important role in maintaining the health of its native rivers—displacing invasive carp. 

Though historically unpopular as a sport fish, the bigmouth buffalo is increasingly a target of bowfishers, which shoot fish with bow-and-arrow, often at night with spotlights.

Almost all U.S. states where bigmouth buffalo are found have no limits on sport or commercial harvests. The fish is not considered threatened in the U. S. but is of special conservation concern in Canada. Lackmann and David hope the discovery of the bigmouth buffalo’s amazing longevity will help boost its profile.

“I hope that knowing this cool fact about them will have people look at this species more closely,” David says.

Read More