Daily Archives: October 11, 2016
iPhoneOgraphy – 11 Oct 2016 (Day 285/366)
Alligator gar (Atractosteus spatula) are ray-finned euryhaline fish related to bowfin in the infra class Holostei (ho’-las-te-i). The fossil record traces their existence to the Early Cretaceous over a hundred million years ago. They are the largest species 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 alligator, particularly their broad snout and long sharp teeth. Anecdotal evidence in several scientific reports suggest that an alligator gar can grow up to 10 ft (3.0 m) in length and weigh as much as 300 lb (140 kg); however in 2011 the largest alligator gar ever caught and officially recorded was 8 ft 5 1/4 in (2.572 m) long, weighed 327 lb (148 kg), and was 47 in (120 cm) around the girth.
The body of an alligator gar is torpedo shaped, usually brown or olive fading to a lighter gray or yellow ventral surface. Their scales are not like the scales of other fishes; rather, they have ganoid scales which are hard, enamel-like, diamond-shaped scales, often with serrated edges. Ganoid scales are nearly impenetrable and have served the fish well as protection against predation. Unlike other gar species, the upper jaw of an alligator gar has a dual row of large sharp teeth which are used to impale and hold prey. Alligator gar are stalking, ambush predators, primarily piscivores, but they will also ambush and eat water fowl and small mammals they find floating on the water’s surface.
Populations of alligator gar have been extirpated from much of their historic range as a result of 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 gar were considered “trash fish”, or a “nuisance species” detrimental to sport fisheries; therefore, were targeted for elimination by state and federal authorities in the United States. The 1980s brought a better understanding of the ecological balance necessary to sustain an ecosystem, and eventually an awareness that alligator gar were no less important than any other living organism in the ecosystems they inhabit. Over time, alligator gar were afforded some protection by state and federal resource agencies. They are also protected under the Lacey Act which makes it illegal to transport certain species of 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 gar 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 are the largest species in the gar family, and among the largest freshwater fishes found in North America. Mature alligator gar commonly measure 6 ft (1.8 m) in length, and weigh over 100 lbs. (45 kg). However, anecdotal reports suggest they can grow up to 10 ft (3m) in length, and weigh as much as 350 lbs. (159 kg). 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 (2.572 m) long, weighed 327 lb (148 kg), and its girth was 47 in (120 cm). According to wildlife officials, the fish was estimated to be somewhere between 50 and 70 years old; one report estimated the gar’s age to be at least 95. 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 gar 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.