The Mississippi River floodplains are home to one of Earth’s most impressive river monsters: the alligator gar. Known to science as Atractosteus spatula, it is the largest of the gar species alive today and among the largest fish in North America.
Dr Solomon David, AKA “The Gar Guy”, has had more experience than most with these freshwater giants. So, when he messages you to say his team recently caught “the largest alligator gar I’ve encountered,” you pay attention – especially during #GarWeek.
In a post shared on X and Bluesky, David shared pictures of the 240-centimeter (7-foot 10-inch) alligator gar in all its glory. At around 136 kilograms (300 pounds), it had the research boat tipping, but together the team were successfully able to capture, tag, and release it back into the wild.
I’d guess the fish was at least 50 years old, but it could have easily been 90.
Dr Solomon David
“This fish was truly gargantuan, and I don’t use that term (or pun) lightly!” said David to IFLScience. “It is the longest gar I’ve encountered in person, and along with that the largest (girth and weight). There are certainly longer alligator gars that have been caught, but this fish was particularly wide, just a massive head and body, like nothing myself or anyone on our team had seen before.”
“The jaw morphology (tooth patterns in particular) and fins also indicated what is likely a very old fish. I’d guess the fish was at least 50 years old, but it could have easily been 90 years. Alligator gars grow slowly after reaching about six feet [1.8 meters] long, and we know the species can live for over 100 years.”
The team were successfully able to capture, tag, and release the enormous alligator gar.
Image courtesy of Dr Solomon David
This kind of tag and release is part of a study into the Mississippi River floodplain restoration that is looking at how the large river connects to its floodplains. Gars make handy indicators for assessing connectivity because they use the floodplains for spawning, feeding, and as nursery areas.
“Alligator gars in particular migrate onto these floodplains as integral parts of their life cycle,” said David. “So, finding large alligator gars at this site is a really good sign of connectivity with the river, and restoration efficacy.”
“We are teamed up with The Nature Conservancy Mississippi on this project, with director Scott Lemmons who led the overall restoration project. Our team is investigating the ecology, life history, and habitat use of alligator gars and other gar species in this critical habitat.”
Why so enormous?
The incredible size of alligator gars comes down to a voracious appetite that’s shared by all seven living gar species. They’ll eat just about anything that fits in their mouths, but they still remain vulnerable to changes in the environment.
They are opportunistic predators, so if they can swallow it, they will eat it.
Dr Solomon David
“They are opportunistic predators, so if they can swallow it, they will eat it,” said David. “This makes them harmless to humans, however, as their mouths aren’t large enough to swallow a person (you’re safe from gars in our waters!).”
“The large rivers, their associated floodplains, lakes, and coastal areas that alligator gars call home have abundant sources of food, allowing them to grow to these massive sizes, but these habitats are becoming more and more modified by humans. Dams and levees along large rivers can prevent alligator gars from reaching their spawning grounds. In some places there is unlimited harvest for alligator gars, which can have impacts on local populations of the species, as these are late-maturing and long-lived fish.”
The alligator gar – a living fossil?
Gars are sort of like the poster child for “living fossils”. A living fossil is considered to be an animal alive today whose characteristics, or phenotype, reflect those of a species known only from the fossil record. It was a term coined by Charles Darwin in 1859, but one that’s been used in varied and unclear contexts ever since.
In 2024, a study co-authored by David became the first to identify a biological mechanism that could explain why some animals remain seemingly frozen in time like this. In some living fossils, evolution really does occur at a drastically slower rate, and it means they can create viable hybrids with other species – even when they haven’t shared a common ancestor since dinosaurs walked the Earth.
A record-breaking hybrid
Hybrids discovered between the alligator gar and longnose gar represent the offspring of genetically isolated groups whose last common ancestor existed 100 million years ago, making it the oldest identified parental split across animals, plants, and fungi. These hybrids are rare, but not unheard of. By a stroke of sweet serendipity, one of study co-author David’s graduate students – Kati Wright of Nicholls State University – actually caught one the same week as the above-mentioned living fossil paper’s publication.
The ancient splits of the alligator gar and longnose gar demonstrate the slow rate of evolution seen among gars – a group of primitive fishes that David says are often wrongfully considered “trash fish”, and yet we stand to learn so much from them. It’s thought they may have super-efficient DNA repair that could explain the low species diversity, and if so, could inform research into human health and cancer.
So, a fascinating fish we can all agree, and if you’ve enjoyed this whopper, then why not meet one of its relatives: the spotted gar.
Source Link: “Behold The GARLIATH!”: Enormous “Living Fossil” Hauled From Mississippi Floodplains Stuns Scientists