Longnose gar

The longnose gar (Lepisosteus osseus), also known as needlenose gar, longnose garpike, and billy gar, is a ray-finned fish in the family Lepisosteidae. The genus may have been present in North America for about 100 million years.[4] There are references to gars being a primitive group of bony fish because they have retained some primitive features, such as a spiral valve intestine, but gars are a highly evolved group of fish, and not primitive in the sense they are not fully developed.

Longnose gar
At the New England Aquarium

Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Lepisosteiformes
Family: Lepisosteidae
Genus: Lepisosteus
Species:
L. osseus
Binomial name
Lepisosteus osseus
Synonyms[2][3]
US distribution of longnose gar
Mark Catesby, The Green Gar Fish (Esox osseus), published 1731-1743. An eighteenth-century print with Linnaeus' original name for the longnose gar.
Longnose gar (‘’L. osseus)
Georgia Aquarium

They have an olive brown to green torpedo-shaped body armored with ganoid scales, elongated jaws that form a needle-like snout nearly three times the length of its head, and a row of numerous sharp, cone-shaped teeth on each side of the upper jaw.[5][6] They typically inhabit freshwater lakes, brackish water near coastal areas, swamps, and sluggish backwaters of rivers and streams. They can breathe both air and water which allows them to inhabit aquatic environments that are low in oxygen.

Longnose gar are found along the east coast of North and Central America, and range as far west in the US as Kansas, Texas and southern New Mexico. It is the only species of the family Lepisosteidae that is found in New Mexico. Their populations are stable and in some areas abundant in the interior portions of its range.[5]

Etymology

The longnose gar was first described by Carl Linnaeus (1758), who gave it the name Esox osseus.[7] The name Esox, which is the genus for pike, was later changed to Lepisosteus, the genus for slender gars. Lepisosteus osseus (Linnaeus, 1758), the scientific name for longnose gar, originated by combining lepis, which is Greek for scale, and osteos, the Latin word for bony. The latter references the bone-like, rhomboidal-shaped ganoid scales that protect gars against predation.[7]

Gars have been referred to as primitive fish or living fossils because they have retained some morphological characteristics of their earliest ancestors, such as a spiral valve intestine, and a highly vascularized swim bladder lung that supplements gill respiration for breathing both air and water.[8][9][10] Gars are highly evolved; therefore, referring to them as primitive fish simply means they have existed for a long time, having evolved over millions of years into a more perfected morphological state, not that the animal is primitive in the sense that it is not fully developed.[11]

Distribution

Fossils of the genus dating back 100 million years have been found in Africa, Asia, Europe, North America, and South America. In the US, fossils of the modern species date back to the Pleistocene were they were discovered in the Kingsdown Formation in Meade County, KS and date back to the Irvingtonian (1.8 - 0.3 MA).[12] Longnose gar are found in Central America, Cuba, North America, and the Isla de la Juventud.[13]

Longnose gar are frequently found in fresh water in the eastern half of the United States, but some gar were found in salinities up to 31 ppt.[14] Their microhabitats consist of areas near downed trees, stone outcrops, and vegetation.[15]

Ecology

The most common prey of longnose gar are small fish and occasionally insects and small crustaceans; they mostly feed at night.[16] Their main competitors are other garfishes, and it is somewhat common for large gar to feed on smaller ones.[17] Historically, Native Americans and early colonists harvested longnose gar as a main food source.[18] Over time, longnose gars have gained in popularity as a sportfish rather than as a food source; however, some people consider gar meat a delicacy. Adult longnose gar are considered apex predators in their aquatic habit, and have few predators which include humans, and the American alligator in the southern reaches of their range.[5] They are most vulnerable to predation when they are young, and are preyed upon by other garfishes, larger fishes, birds of prey, snapping turtles, and water snakes.[19]

Life history

Longnose gar have an average lifespan of 15–20 years with a maximum reported age of 39. This long lifespan allows the female to sexually mature around six years old. Males mature sexually as early as two years of age. Longnose gar are sexually dimorphic; the females are larger than the males in body length, weight, and fin length. They generally have a clutch size close to 30,000, depending on the weight to length ratio of the females; larger females bear larger clutch sizes. They spawn in temperatures close to 20°C in late April and early July.[20] Eggs have a toxic, adhesive coating to help them stick to substrates, and they are deposited onto stones in shallow water, rocky shelves, vegetation, or smallmouth bass nests.[21] Their hatch time is seven to 9 days; young gar stay in vegetation during the first summer of life.[16] Longnose gar reach an typical length of 28-48 in (0.71-1.2 m) with a maximum length around 6 ft (1.8 m) and 55 lb (25 kg) in weight.

Management

Currently, no management of this species is being conducted, nor is it federally listed as endangered, although some states have reported it as threatened (South Dakota, Delaware, and Pennsylvania).[22] In the early 1900s, longnose gar were considered as destructive predators. Soon after this characterization, gar population reduction methods were established. Their declining populations are due to overfishing, habitat loss, dams, road construction, pollution, and other human-caused destruction of the aquatic systems. Because of their long lifespans and older sexual maturity age, factors affecting their reproduction is an issue in preserving them.[23] Overfishing is a large issue for this fish, especially when the fish have not reached sexual maturity due to the female not reaching sexual maturity until about six years of age.[23]

References
  1. NatureServe (2015). "Lepisosteus osseus". IUCN Red List of Threatened Species. 2015. Retrieved April 7, 2016.CS1 maint: ref=harv (link)
  2. Froese, R.; Pauly, D. (2017). "Lepisosteidae". Retrieved 18 May 2017.
  3. "Lepisosteidae" (PDF).
  4. McGrath, P.E., E.J. Hilton (2011). Sexual dimorphism in longnose gar Lepisosteus osseus. Journal of Fish Biology 80(2)335-345
  5. "Lepisosteus osseus". Florida Museum. 2017-05-10. Retrieved 2019-08-04.
  6. "longnose gar Lepisosteus osseus". Texas Freshwater Fishes (UT Austin mirror of http. 2012-12-15. Retrieved 2019-08-04.
  7. "Lepisosteus osseus". Florida Museum. 2017-05-10. Retrieved 2019-10-07.
  8. Tyus, Harold M. (2011). Ecology and Conservation of Fishes. CRC Press. p. 46. ISBN 9781439858547.
  9. Goddard, Nathaniel. "Alligator Gar". FLMNH Ichthyology Department. Retrieved April 19, 2014.
  10. Graham, Jeffrey B. (1997). Air-Breathing Fishes: Evolution, Diversity, and Adaptation. Academic Press. pp. 1–10. ISBN 978-0-12-294860-2.
  11. "Alligator Gar (Atractosteus spatula)". 2011. Retrieved October 7, 2019.
  12. "Lepisosteus osseus Linnaeus 1758". PBDB.
  13. Wiley, E.O. (1976). The phylogeny and biogeography of fossil and recent gars (Actinopterygii: Lepisosteidae). Miscellaneous Publication, University of Kansas, Museum of Natural History 64.
  14. Uhler, P.R. & O. Lugger. (1876). List of fishes of Maryland. Report of the Commissioners of Fisheries of Maryland, to the General Assembly
  15. Suttkus, R.D. (1963). Order Lepisostei. In: Fishes of the Western North Atlantic, Memoir 1, Part Three, of the Sears Foundation for Marine Research (H. B. Bigelow, C. M. Cohen, G. W. Mead, D. Merriman, Y. H. Olsen, W. C. Schroeder, L. P. Schultz, and J. Tee-Van, eds.), pp. 61-88. New Haven, CT: Yale University.
  16. Haase, B.L. (1969). An ecological life history of the longnose gar, Lepisosteus osseus (Linnaeus), in Lake Mendota and in several other lakes of southern Wisconsin. Dissertation, the University of Wisconsin - Madison, Madison, Wisconsin.
  17. Bonham, Kelshaw. (1941). Food of gars in Texas. Transactions of the American Fisheries Society 70(1):356-362.
  18. Straube, B. and N. Luccketti. (1996). Jamestown rediscovery 1995 interim report. November 2006. The Association for the Preservation of Virginia Antiquities, 55 p.
  19. "Gar Family (Lepisosteidae)" (PDF). Indiana Division of Fish and Wildlife. pp. 2–5. Retrieved 4 August 2019.
  20. Netsh, Norval F., Arthur Witt Jr. (1962). Contributions to the Life History of the Longnose Gar (Lepisosteus osseus) in Missouri. Transactions of the American Fisheries Society 91(3):251-262.
  21. Beard, J. (1889). On the early development of Lepidosteus osseus. Proceedings of the Royal Society of London 46:108-118.
  22. Johnson, Brian L., Douglas B. Noltie. (1997). Demography, Growth, and Reproductive Allocation in Stream-Spawning Longnose Gar. Transactions of the American Fisheries Society 126:438-466.
  23. Alfaro, Roberto Mendoza, et al. (2008). Gar biology and culture: status and prospects. Aquaculture Research 39:748-763
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