Northern snakehead (Zoology)
Contents
Northern snakehead
Northern snakehead (Channa argus). Source: U.S.Geological Survey
The northern snakehead (Channa argus) is a freshwater fish (China) native to China, North Korea, South Korea and Russia, which has been introduced to portions of the USA, where it is considered an alien species with significant adverse habitat destruction capacity. This fish has the extraordinary capability of being able to travel over land for over one fourth of a mile, and it can remain out of water for periods of up to four days. The species is quite aggressive and consumes a wide variety of prey animals. Other newly minted common names derive from its invasion of the USA and include fishzilla and fish from Hell.
This fish has the ability to breathe air directly by use of a special superbranchial organ; this capability enhances its capacity to colonize and invade new territory by moving from river to nearby pond, for example. Recently the State of Maryland has offerred a bounty of $200 per fish caught, to anglers who capture this species, in a move to try to extirpate this invasive species.
Morphology
The northern snakehead. Source: U.S.Geological Survey The northern snakefish is rather elongated in body shape, exhibiting a single dorsal fin running the about two thirds the body length (e.g. from about the rear of the gill area to almost the tailfin). C. argus manifests a single long anal fin similar to the bowfin (Amia calva). Total coloration is brownish accompanied by dark blotches. This species has a flattened head with eyes positioned in a dorso-lateral position on the anterior portion of the head. Tubular anterior nostrils are evident; moreover, dorsal and anal fins present as elongated, and all fins are supported by rays only; the dorsal fin has 49 or 50 rays. Maximum adult length of this fish is typically 85 to 100 centimeters, and body mass may be as great as eight kilograms.
This fish has the capability to extract oxygen from air, invoking a special organ known as a suprabranchial structure. Such a respiratory feature allows the species to travel considerable distances on land, enhancing its invasive capabilities. However, this species also has a bifurcated ventral aorta, leading to an ability to perform respiration underwater as well.
The northern snakehead has a large mouth extending well to the rear of the eye; it also manifests shaggy teeth occurring in bands, large lower jaw canines as well as palatines.
Distribution
Alien distribution of northern snakehead in the USA. USGS 2012 The native range of this fish taxon is east Asia including portions of Russia, China and both Koreas; however, it has come to the attention of the Western World chiefly due to its invasive activities, mainly along eastern seaboard freshwater systems. According to the U.S. Geological Survey, the introduction of this fish likely arose in the USA since it “is popular in the Asian food market and most introductions were likely released for this purpose. This was the case in a founding USA individuals of the Crofton pond population in Maryland.” This fish is considered an established alien species in the states of Virginia, Maryland, Pennsylvania, New York and Arkansas. Channa argus is not deemed established in California, Florida, Illinois, Massachusetts, Delaware, and North Carolina, in which states only a few individual fish have been collected.
USA invasion details
Over the past decade or so, the number of reported snakehead citings around the U.S. has increased. The earliest observation of C. argus in the wild within the USA derived from Silverwood Lake, California in the year 1997. The first east coast USA sighting occurred in 2000 in the St. Johns River below Lake Harney, Florida. In June 2002, an established population of this species was discovered in a pond in Crofton, Maryland. This population was eradicated by state biologists using rotenone, a non-specific piscicide. A single fish was collected in Lake Michigan, Burnham Harbor in downtown Chicago, Illinois in 2004. The species has been reported from two sites in Massachusetts, in 2001 and in 2004. In July 2005, C. argus was reported in Meadow Lake in Queens, New York. In late May and early June 2008, three northern snakeheads were collected from in-stream in Wawayanda, New York.
State Officials believe C.argus may have reached the lower Schuylkill River and Delaware River in Pennsylvania; however, they see no practical means to eradicate them. In March 2009, the population in Little Piney Creek drainage was eradicated with the application rotenone to more 700 linear kilometers of creeks, ditches, and backwaters. The invasive C.argus population in Catlin Creek, New York was also treated with rotenone.
in 2004, several northern snakeheads were captured in the Potomac River in Virgina and Maryland. The Potomac River population now is deemed to range throughout the lower Potomac from Great Falls to the mouth, including some tidal portions with moderate salinity (up to 7.6 parts per thousand.) Another northern snakehead was collected in Dogue River in Fairfax County, Virginia. A single specimen was collected from Massey Creek and in 2005 a breeding female was found in Little Hunting Creek, a tributary of the Potomac within Virginia. Many other C. argus speciemens were collected in 2006 and 2007 in the Potomac basin centering around Dogue and Little Hunting creeks in Virginia and from the Anacostia River in Maryland. In April 2008, a single C. argus was seen in a ditch near Monroe, Arkansas, led to the conclusion that a C. argus population was established.
Habitat
Channa argus tolerates an exceptional range of latitude and water temperature environments, which capabilities help to explain the ability to adapt and propagate in non-native waters; in fact, this species can tolerate water temperatures from freezing to 30 degrees Celsius. This fish is a considered a freshwater species, although it is found in salinities of up to ten parts per thousand. Its repiratory system of direct oxygen intake from the air allows it to be classified additionally as a terrestrial organism. C. argus prefers aquatic habitat of slow or stagnant waters, and is typically found above muddy or heavily vegetated benthic environments.
Behavior
C. argus can travel over land as well as through freshwater; in fact, this carnivore has been recorded as traveling over one fourth mile out of water, using a forward wriggling motion propelled by lower fins. This fish is exceptionally aggressive, and consumes a wide variety of prey fauna. Juveniles prey upon zooplankton, insect larvae, small crustaceans and fry of other fish species. Adults feed chiefly on other fish taxa, with the balance of their intake comprised of crustaceans, frogs, small reptiles, and even small birds and mammals.
Taxonomy
The northern snakehead was first described by Danish physician and zoologist Theodor Edvard Cantor in the year 1842. Cantor was particularly active in discovering previously undescribed taxa of reptiles and amphibians. Two subspecies are recognized: Channa argus argus from China and the Koreas and Channa argus warpachowskii found in eastern Russia.
References
Potomac River, Washington DC, invaded habitat of C. argus. @ C.Michael Hogan
- W.R.Courtenay Jr and J.D.Williams. 2004. Snakeheads (Pisces: Channidae) -- A biological synopsis and risk assessment. U.S. Department of the Interior, U.S. Geological Survey Circular 1251, 143 p.
- M.Flarherty. 2008. New York State Department of Environmental of Conservation.
- P.F.Fuller, A.J. Benson and M.E. Neilson. 2012. Channa argus. USGS Nonindigenous Aquatic Species Database, Gainesville, Florida
- J.B.Graham. 1997. Air-breathing fishes: evolution, diversity, and adaptation. Academic Press, San Diego, California, 299 pp
- L.Holt. 2009. Arkansas Game and Fish Commission. Personal communication.
- Thomas M.Orrell and Lee Weigt. The Northern Snakehead Channa argus (Anabantomorpha: Channidae), a non-indigenous fish species in the Potomac River, U.S.A.. Proceedings of the Biological Society of Washington, 118(2):407–415.
- W.C.Starnes., J.Odenkirk and M.J.Ashton. 2011. Update and analysis of fish occurrences in the lower Potomac River drainage in the vicinity of Plummers Island, Maryland—Contribution XXXI to the natural history of Plummers Island, Maryland. Proceedings of the Biological Society of Washington 124(4):280-309.
- USDA National Agricultural Library, 2011. Northern Snakehead. Species Profiles. National Invasive Species Information Center.
