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| © Photograph by Joel Sartore, National Geographic Photo Ark This bigmouth buffalo (Ictiobus cyprinellus) was photographed at Gavins Point National Fish Hatchery and Aquarium, in South Dakota. Carbon dating has validated that the species is the longest-lived freshwater fish known. |
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 aging 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 these fish, 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. (Related: "Meet the animal that lives for 11,000 years.")
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-1900s 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.
Aging 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. (See "Rare whales can live to nearly 200, eye tissue reveals.")
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. (See the overlooked world of freshwater animals.)
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.
