Longnose Gar

Longnose Gar, Lepisosteus osseus

The Longnose Gar, Lepisosteus osseus, whose common Spanish name is catán aguja, is a species in the Gar or Lepisosteidae Family, known collectively as pejelagartos in Mexico. This fish is also known as the Needlenose Gar. The gars are scientifically interesting as they are very primitive and date to the Cretaceous Period, 145 to 66 million years ago. There are currently seven living gars placed in two genera. Globally, there are four species in the genus Lepisosteus, of which one is found in Mexican waters; it is found in the freshwater systems of the Atlantic and is the fish described here.

The Longnose Gars have elongated and torpedo-shaped bodies. They are olive-brown dorsally and transition to white ventrally. They vary in color based on the water quality with fish from clear water being much deeper green than those from murky water which are drab brown. They have spots on their anal, dorsal, and caudal fins, as well as on their upper back. Juveniles have a black stripe on their sides. They have a long narrow snout that is nearly twice the length of the head. They are equipped with a single row of long sharp villiform teeth. Their anal fin and their single dorsal fin are set well back on the body and have 8 to 10 rays and 6 to 9 rays, respectively. Their pectoral fins are low on the body and their pelvic fins are in the middle of the belly. There have scutes on the leading edges of their unpaired fins and on both edges of their caudal fin. They have 14 to 31 gill rakers. They are covered with thick overlapping scales with black margins, which provide them with a suit of armor and allow adults to be free from predation.

The Longnose Gars are found at depths up to 30 feet primarily in large weedy lakes and reservoirs, backwaters and quiet pools of medium to large rivers, stagnant ponds, sloughs, canals, brackish waters of coastal inlets, and occasionally in coastal marine waters; they are often found near vegetation or close to submerged or overhanging objects by day. They are slow growing and can reach 2.0 meters (6 feet 8 inches) in length and 22.8 kg (50 pounds) in weight. Young tend to occupy shallows, whereas larger individuals are found in deeper water. They prefer water temperatures between 12oC (54oF) and 20oC (68oF). They are sexually dimorphic with females being larger than males in length and weight and living about two times longer. They are nighttime ambush predators that lie in wait and consume small fish (sunfish, catfish, crayfish), insects, and small crustaceans. They are also known to practice cannibalism. Their only known predator is the American Alligator, Alligator mississippiensis. As such they are an important apex predator in many ecosystems. Fish will migrate from brackish water to fresh water for spawning. Each female can lay up to 30,000 eggs annually. The eggs and larvae are demersal and adhesive; they attach themselves to shallow water substrates including stones and plant life. They have a toxic coating to help avoid predation. They have the ability to survive in higher salinity waters than most fish and in low oxygen waters as they can gulp air due to their modified swim bladder. They have a lifespan of up to 36 years.

In Mexican waters the Longnose Gars have a limited distribution being found in coastal brackish waters and within the freshwater systems that drain into the Gulf of Mexico from Tuxpan northward to the United States border in the State of Veracruz.

The Longnose Gar is straightforward to identify due to the length of its snout which is more than twice the length of the head and its diamond-shaped interlocking scales, thus it cannot easily be confused with any other species. The Alligator Gar, Atractosteus spatula, is somewhat similar but has a double row of teeth on its upper jaw.

The Longnose Gars are sought after on a limited basis by recreational anglers, including bow fishermen, but are generally regarded as nuisance fish. From a conservation perspective, they are currently considered of Least Concern with populations estimated to be in excess of 100,000 individuals. Although widespread, there is a long-term concern for the survival of the species due to overfishing and human-caused habitat destruction. They were an important source of food for Native Americans and early colonists. They can also be found in large public aquariums as they are hardy and easy to maintain.

Longnose Gar, Lepisosteus osseus. Fish caught out of the Santee River, South Carolina, August 2010. Total length 97 cm (38 inches). Catch, photo, and identification courtesy of Josh Leisen (lifelistfishing.com), Gaylord, MI.