Alligator Gar: A Living Texas Fossil

By Jason Naivar, Education Program Coordinator

Of all the fish in the continental United States, alligator gars are perhaps the most misunderstood. With a long, tapered snout full of sharp, jagged teeth and a small, flattened skull, this ancient fish hasn’t changed much since the Cretaceous period. Its scientific name in Latin, Atractosteus spatula, roughly translates to “spindle-bone flat-spoon,” an apt description for its skull.

Despite their frightening appearance, I’ve only had positive interactions with these creatures. Over the years, I’ve spent more than 5,000 hours underwater – feeding, cleaning, and maintaining the large aquarium of two adult alligator gars – and have come to deeply admire their unique abilities.

My goal is to help reshape perceptions of these fascinating creatures and emphasize the importance of their place in the natural world.


Super Fish Facts

Alligator gars, one of the most ancient species of inland bony fish, have existed for more than 100 million years. These large predators are at the top of the food chain and possess adaptations that let them live where others perish. They grow up to 10 feet long and can weigh more than 200 pounds, with the state and national record holders weighing 279 pounds and 327 pounds, respectively.

Gars are also remarkably long lived, regularly reaching 30 to 50 years old, with a few living into their 80s and 90s. Measuring an alligator gar is a quick way to estimate its age. A gar that grows 7 feet long would be approximately 40 years old.

Another impressive aspect of the gar is its ability to adapt to a variety of water conditions, a trait known as euryhalinity, which in Latin translates to “wide” and “salt.” This ability allows the fish to adapt to water that is fresh, brackish, or high in salt. As the fish absorbs water, specialized gills and kidneys enable it to collect and release salts to keep its body salinity in balance. The transition between salinities must be gradual, however, as would occur naturally in a coastal estuarine environment. Along the coast, gars range from western Florida to Mexico. Freshwater populations exist inland as far as Arkansas, Missouri, and Oklahoma.

The ideal habitat for the alligator gar is a slow-moving body of water that allows them to swim with little effort and conserve energy, a practice crucial to their feeding strategy. Like most fish, gars absorb oxygen through their gills as they swim. But in slow-moving water with no wind, water oxygen levels may drop too low for most fish. Gars can cope with low oxygen levels because they have a unique swim bladder used to control buoyancy. By gulping air and storing it in the swim bladder, gars can absorb oxygen through the bladder’s lining directly into their bloodstream. Interestingly, this mechanism also causes gars to burp.

To catch their prey, gars lie still in the water like a log. When a smaller fish or animal gets too close, these predators use their powerful muscles, elongated mouth, and sharp cone-shaped teeth to grab it in one deft move. Using their powerful caudal fin in a pulling motion, they snap their jaws to the side with blinding speed. Its bite swath extends from the tip of its snout nearly to each eye. This side to side action increases the bite area and overall success of the attack (see fig. 1). Once its target is immobilized, the gar will work to reposition and swallow it whole.

Once a gar reaches 3 to 4 feet long, its only natural predator is the American alligator. For protection, these fish feature hard ganoid scales that are angled and spaced to provide flexibility. Be careful when handling gars, as their scales are sharp and can cut flesh.


Monster Myths

Because of their unusual appearance, alligator gars have acquired an unflattering reputation over the years. Let’s explore and address a few of the most common misconceptions.


They are aggressive and attack people.

As with most large predators, alligator gars are lethal to their prey. But around humans, they tend to be shy, cautious, and deliberate in their actions. Although there has never been a confirmed report of an unprovoked attack on a human, alligator gars will fight an angler fiercely if caught, sometimes injuring their opponent. Many purported gar attacks later turned out to be American alligator attacks once bite patterns were analyzed.


They eat all of the gamefish.

Because of their large size, many people assume alligator gars need a large amount of fish to survive. Nothing could be further from the truth. Gars are opportunistic feeders that may consume birds, rodents, crabs, reptiles, amphibians, and even carrion. After proper feeding, they could easily survive a month without food. Wondering how they do it?

Simply put, they possess a slow metabolism, use efficient movements, are cold-blooded, float rather than swim, and have a small brain-to-body size ratio. Humans have a large brain-to-body ratio, are warm-blooded, and live on land. We need large amounts of calories each day to fuel our bodies, maintain a steady temperature, and power our muscles to fight gravity. If humans and gars were vehicles and calories were the gasoline, a gar would be a Toyota Prius and a human would be a monster truck.


They are trash fish.

The term “trash fish” usually implies that the animal is inedible, lacks environmental value, and provides little sport for anglers. Not only are gars flavorful, they also play a significant role in maintaining healthy fish populations and provide a challenge for anglers.

Catching them often requires heavier than normal tackle and patience, as they can effortlessly spit out fishing hooks that don’t latch to their mouth correctly. Bowfishing is a new method for catching gar, but it requires skill and specialized equipment. Those skilled enough to capture a gar can enjoy flavorful meat if they prepare the fish properly.


Alligator gar are everywhere in Texas

With all these impressive adaptations, there is still one danger they haven’t evaded: humans. Overfishing, construction of dams, flood control devices, and overall habitat loss are the primary reasons for declining gar populations. Its reputation as a nuisance animal has also contributed to low regional populations. As a result, government agencies in some states have laws protecting the alligator gar.

Additionally, apex predators, like gars, are slow to reproduce, reaching sexual maturity around 10 years of age. Spawning conditions are not always optimal, so this species can go for years without reproducing. Low reproduction rates plus slow maturation can make gar vulnerable to overfishing. When they do spawn, the eggs are poisonous for most animals to eat.

When it comes to alligator gars, the idiom “Don’t judge a book by its cover” is appropriate. Beneath that rough-and-tough exterior is a sensitive survivor who just wishes to be left alone. We can help these gentle giants by learning about them and showing them proper respect. With continued education, we may see more of these beneficial creatures in lakes, creeks, and marshes throughout the region.