Alligator gar

Atractosteus spatula

Alligator gars, ''Atractosteus spatula'', are ray-finned euryhaline fishes related to bowfin in the superorder Holostei . The fossil record traces the existence of alligator gars back to the Early Cretaceous over a hundred million years ago. They are the largest in the gar family, and among the largest freshwater fishes in North America. Gars are often referred to as "primitive fishes", or "living fossils" because they have retained some morphological characters of their earliest ancestors, such as a spiral valve intestine which is also common to the digestive system of sharks, and they can breathe both air and water. Their common name was derived from their resemblance to American alligators, particularly their broad snout and long sharp teeth. Anecdotal scientific reports suggest that alligator gars can grow to 10 ft and weigh 300 lb , however in 2011 the largest alligator gar ever caught and officially recorded was 8 ft 5 1⁄4 in long, weighed 327 lb , and was 47 in around the girth. Their bodies are torpedo shaped, usually brown or olive fading to a lighter gray or yellow ventral surface. They do not have scales like other fishes, rather they are armored for protection against predation with hard, enamel-like, jagged diamond-shaped ganoid scales that are nearly impenetrable. Unlike other gar species, mature alligator gars have a dual row of large sharp teeth in the upper jaw which they use for impaling and holding prey. They are stalking, ambush predators that are primarily piscivores, but will also ambush and eat water fowl and small mammals that may be floating on the surface.

Alligator gars have been extirpated from much of their historic range through habitat destruction, indiscriminate culling, and unrestricted harvests. Populations are now located primarily in the southern portions of the United States extending into Mexico. They are considered euryhaline because they can adapt to varying salinities ranging from freshwater lakes and swamps to brackish marshes, estuaries, and bays along the Gulf of Mexico.

For nearly a half-century, alligator gars were considered "trash fish", or a "nuisance species" that were detrimental to sport fisheries, and therefore targeted for elimination by state and federal authorities in the United States, but the last ten years has seen a greater emphasis placed on the importance of alligator gars to the ecosystems they inhabit. As a result, they were afforded protection by restricted licensing. They are also protected under the Lacey Act which makes it illegal to transport fish in interstate commerce when in violation of state law or regulation. Several state and federal resource agencies are monitoring populations in the wild, and have initiated outreach programs to educate the public. Alligator gars are being cultured in ponds, pools, raceways and tanks by federal hatcheries for mitigation stocking, by universities for research purposes, and in Mexico for consumption.
Alligator Gar - Atractosteus spatula Alligator Gar - Atractosteus spatula seen at Singapore River Safari Alligator gar,Atractosteus spatula,Garfish,Geotagged,Singapore,Summer

Appearance

Alligator gars are the largest species of gar, and among the largest freshwater fishes found in North America. Mature alligator gars commonly measure 6 ft in length, and weigh over 100 lbs. . However, anecdotal reports suggest they can grow up to 10 ft in length, and weigh as much as 350 lbs. . The largest alligator gar officially recorded was inadvertently caught in the net of fisherman Kenny Williams of Vicksburg, Mississippi while he was fishing the oxbow lakes of the Mississippi River on February 14, 2011. Williams was pulling up his net on Lake Chotard expecting to find buffalo fish, but instead discovered a large alligator gar tangled in his net. The gar was 8 ft 5 1⁄4 in long, weighed 327 lb , and its girth was 47 in . According to wildlife officials, the fish was estimated to be somewhere between 50 and 70 years old. Williams donated it to the Mississippi Museum of Natural Science in Jackson where it will remain on display.


All gars have torpedo-shaped bodies, but some distinguishing characteristics of adult alligator gars include their large size, heavy bodies, broad heads, short broad snouts, large sharp teeth and double row of teeth on their upper jaw. They are usually brown or olive fading to a lighter gray or yellow ventral surface. The dorsal and anal fins are positioned toward the back of their bodies, and their caudal fin is abbreviate-heterocercal, or non-symmetrical.

Alligator gars have gills, but unlike other fishes they also have a highly vascularized swim bladder lung that supplements gill respiration. The bladder not only provides buoyancy but also enables them to breathe in air which is why they are able to inhabit bodies of water in which most other fishes would die of suffocation. The bladder is connected to their mouth through a small pneumatic duct that allows them to breathe or gulp air when they break the surface, an action that is seen quite frequently on lakes in the southern United States during the hot summer months. The scales of alligator gars are not like the scales of other fishes; their bodies are protected by overlapping, enamel-like ganoid scales that are diamond-shaped with jagged edges and composed of a hard inner layer of bone and an outer layer of ganoin that is nearly impenetrable.
Alligator Gar Alligator aquarium. Alligator,Alligator gar,Atractosteus spatula

Behavior

Alligator gars are relatively passive, seemingly sluggish solitary fishes, but voracious ambush predators. They are opportunistic night predators and are primarily piscivores, but they will also ambush and eat water fowl and small mammals that may be floating on the surface. Their method of ambush is to float a few feet below the surface, and wait for unsuspecting prey to swim within reach. They lunge forward, and with a sweeping motion grab their prey, impaling it on their double rows of sharp teeth.

Diet studies have shown alligator gars to be opportunistic piscivores, and even scavengers depending on the availability of their preferred food source. They occasionally ingest sport fishes, but the majority of stomach content studies suggest they feed predominately on forage fishes such as gizzard shad as well as invertebrates, and water fowl. Diet studies have also revealed fishing tackle and boat engine parts in their stomachs.

Food

Alligator gars are relatively passive, seemingly sluggish solitary fishes, but voracious ambush predators. They are opportunistic night predators and are primarily piscivores, but they will also ambush and eat water fowl and small mammals that may be floating on the surface. Their method of ambush is to float a few feet below the surface, and wait for unsuspecting prey to swim within reach. They lunge forward, and with a sweeping motion grab their prey, impaling it on their double rows of sharp teeth.

Diet studies have shown alligator gars to be opportunistic piscivores, and even scavengers depending on the availability of their preferred food source. They occasionally ingest sport fishes, but the majority of stomach content studies suggest they feed predominately on forage fishes such as gizzard shad as well as invertebrates, and water fowl. Diet studies have also revealed fishing tackle and boat engine parts in their stomachs.

Evolution

Lacépède first described the alligator gar in 1803. The original name was ''Lepisosteus spatula'', but was later changed by E.O. Wiley in 1976 to ''Atractosteus spatula'' in order to recognize two distinct extant taxon of gars. Synonyms of ''Atractosteus spatula'' include ''Lesisosteus'' [sic] ''ferox'' , and ''Lepisosteus spatula'' . Fossils from the order Lepisosteiformes have been collected in Europe from the Cretaceous to Oligocene periods, in Africa and India from the Cretaceous, and in North America from the Cretaceous to recent times. Lepisosteidae is the only extant family of gar which has seven species all located in North and Central America. The fossil record traces the existence of alligator gars back to the Early Cretaceous over a hundred million years ago. Despite being a highly evolved species, alligator gars are often referred to as "primitive fishes", or "living fossils" because they have retained a few morphological characteristics of their earliest ancestors with seemingly little to no apparent changes, such as a spiral valve intestine which is also common to the digestive system of sharks, an abbreviate-heterocercal tail, and a swim bladder lung for breathing in both air and water.Native Americans in the south, and Caribbean peoples used the alligator gar's ganoid scales for arrow heads, breastplates, and as shielding to cover plows. Early settlers tanned the skins to make a strong, durable leather to cover their wooden plows, make purses, and various other items. Gar oil was also used by the people of Arkansas as a repellent for buffalo-gnats.

For nearly half a century, alligator gars were considered "trash fish", or a "nuisance species" by state and federal authorities who targeted them for elimination to protect game fish populations, and to prevent alleged attacks on humans, a claim that remains unsubstantiated with the exception of occasional injuries sustained from captured alligator gars thrashing around on the decks of boats. Fishermen participated in the slaughter of thousands of alligator gars believing they were providing a great service. In 1995, KUHT channel 8, a member PBS television station located on the campus of the University of Houston in Texas, distributed and broadcast the first video documentary ever produced on alligator gar. The documentary, "Alligator Gar:Predator or Prey?", debuted nationally in prime time during the July Sweeps, and according to the Nielsen rating report provided to KUHT, was the number one rated program of the evening. The documentary focused on the physiology and life cycle of alligator gars, addressed the destruction of habitat, the unregulated culling and over harvesting of alligator gars from various lakes in Texas and Louisiana, and expressed concerns for the future of the species at a time when it was still considered a "trash fish". A decade passed before any significant action was taken to protect and preserve the remaining populations of alligator gar in the United States. The Missouri Department of Conservation has since partnered with Tennessee, Arkansas, Kentucky, Illinois, Alabama, Mississippi, Texas, Oklahoma, and Louisiana in restoration and management activities.

Cultural

Declining populations of alligator gars throughout their historic range has resulted in the need to monitor wild populations and regulate commercial harvests. Alligator gars have a high yield of white meat fillets and a small percentage of waste relative to body weight. The meat is sold to wholesale distributors, and also sold retail by a few supermarkets with prices starting at around $3.00/lb. Fried gar balls, grilled fillets, and fillets boiled in water with crab boil seasoning are popular dishes in the south. There is also a small cottage industry that makes jewelry out of ganoid scales, and tans gar hides to produce leather for making lamp shades, purses, and a host of novelty items.

''Atractosteus'' gars, including alligator gars, tropical gars, and Cuban gars are considered good candidates for aquaculture particularly in developing regions where their rapid growth, disease resistance, easy adaptation to artificial feeds as juveniles, and ability to tolerate low water quality are essential. Their ability to breathe in both air and water eliminates the need for costly aeration systems and other technology commonly used in aquaculture. In the Southern United States, as well as in parts of Mexico and Cuba, broodstocks have already been established, and are being maintained in their respective regions where they already are a popular food fish.

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Taxonomy
KingdomAnimalia
DivisionChordata
ClassActinopterygii
OrderLepisosteiformes
FamilyLepisosteidae
GenusAtractosteus
SpeciesA. spatula
Photographed in
Singapore