When you think “long-lived,” you generally
think tortoises, redwood trees, and David Attenborough. You don’t usually think fish. Fish are simple creatures that tend to meet
their end in some other animal’s mouth, or floating at the
top of your home aquarium, you know, if you are bad at fish-keeping. So a hundred-year-old fish is pretty special, and a whole genus full of fish centenarians
borders on astonishing. [♪ INTRO] These are the buffalofishes: freshwater fish
in the genus Ictiobus. These fish are native to the Great Lakes and
the Mississippi River, with some species found as far south as Mexico. Buffalofish are not native to Arizona, but
they do live there. Because people put them there more than 100
years ago. In 1911, Theodore Roosevelt dedicated Roosevelt
Dam in his own honor, because that’s the kind
of guy he was. And in 1918, the Bureau of Reclamation stocked the newly created reservoir with buffalofish. At some point, the buffalofish made their
way from Roosevelt Lake to Apache Lake, another reservoir created
by… another dam. And they seem to be doing swimmingly there, even though they’re living in a desert that
they don’t belong in, in a lake that also doesn’t belong there. But what makes this story weird is despite
their fish-out-of-water existence, they’re not
only thriving in Apache Lake, they’re also thriving for decades. See, buffalofish are among the world’s oldest
living animals… at least these ones are. And by “oldest living,” I don’t mean
there’s one or two old buffalofish telling all the other buffalofish
to stay off the lawn, I mean centenarians are the norm. When you move them to an artificial lake in
Arizona, at least. But based on this population, researchers
think hitting the century mark is easily possible for at
least three of the five species of buffalofish. And it’s not that the other two don’t
live that long. It’s that research is still pending. And this isn’t exactly a common thing in
animals. There’s only one other animal genus we know
of with three or more species that have a maximum age of
over 100. The other one is a marine fish, the rockfishes. What’s more, buffalofish also don’t seem to suffer from the effects of age. They don not seem to physically decline the
way humans do. The bigmouth buffalofish kind of gets better
with age, which seems grossly unfair really. In fact, a 2021 study found that older bigmouth
buffalofish tend to have improved immune function and lower stress levels compared to their
younger counterparts. This newfound knowledge about how fish can sometimes surpass the lifespan of humans, when we have the whole of medical science
at our disposal, comes to us courtesy of citizen science. The data was collected by citizen scientist-anglers fishing in Apache Lake, and we love to see
it. It turns out Apache Lake is a better place to do this research than the fish’s native
range. That’s because buffalofish are at risk of
extinction in their native range thanks to overfishing. And it’s hard to study longevity when fish
get caught and eaten before they have a chance to reach the end
of their natural lifespan. Apache Lake is remote and hard to reach, so the buffalofish have been able to live
there mostly undisturbed. For this study, published in Nature Scientific
Reports in 2023, anglers caught, photographed, and released
most of the fish, and donated a few others to scientists. For the 23 fish that were donated, the researchers
could establish an age by looking at the otolith, a structure
in the inner ear that forms rings as it grows like trees do. Almost all of the specimens scientists dissected were older than 80 years. And the researchers think some of them are
the exact same individuals that were stocked in Lake
Roosevelt in 1918. The photographs were also helpful in establishing
an age range for Apache Lake’s buffalofish, since fish older
than 40 have “age spots,” and fish older than 80 have more spots that
are more well-defined. This is, of course, less precise than looking
at the otolith, but the fish gets to swim another day. What’s also super odd is that all of the
fish captured were old — 40 years or older. There don’t seem to be a ton of younger
individuals. Spawning has not been documented in Apache
Lake, even though the scientists checked the individuals
they dissected and, like, everything seemed to be in working order. So the researchers aren’t sure if the fish are breeding or not, and if not, why. Though it’s worth pointing back at the earlier
“neither the fish nor the lake are supposed to be there” thing
to suggest that maybe the conditions really aren’t
right for bringing little buffalofish into the world. The study’s authors feel that their results
are a representative sample of the individuals in the lake, and
not just something that happened by chance – the fish really do
live to be that old. Not only did this study uncover some unknown
information about buffalo fish, but it also cost very
little to conduct, thanks to volunteer anglers. So this has not only taught us something remarkable
about longevity in freshwater fish, but also about the power
of citizen science. So if you’re good with a rod, maybe it’s time to plan a vacation in Arizona. [♪ OUTRO]
