Northern snakehead
Encyclopedia
The Northern snakehead (Channa argus) is a type of snakehead fish
native to China
, Russia
, North Korea
and South Korea
. In the United States
, the fish is considered to be a highly invasive species
. In a well-known incident, several were found in a pond
in Crofton, Maryland in June 2002, which led to major media coverage and two movies about the incident, Snakehead Terror
and Frankenfish
.
with 49-50 rays, anal fin with 31-32 rays, small anteriorly-depressed head, eye above the middle part of the upper jaw, large mouth extending well beyond the eye, villiform teeth in bands, large canine on the lower jaw and palatines, length up to 40 inches (1.0 m), with one report of 60 inches (1.5m), and weight up to 15 pounds (7 kg).
Coloration is a golden tan to pale brown, with dark blotches on the sides and saddle-like blotches across the back. Blotches toward the front tend to separate between top and bottom sections, while rear blotches are more likely to be contiguous. Coloration is nearly the same between juveniles and adults, which is unusual among snakeheads.
Coloration is similar to Channa maculata
, but can be distinguished by two bar-like marks on the caudal peduncle (where the tail attaches): in Channa maculata, the rear bar is usually complete, with pale bar-like areas before and after, while in Channa argus, the rear bar is irregular and blotched, with no pale areas around it.
The Northern snakehead is a freshwater species and cannot tolerate salinity
in excess of ten parts per thousand (Courtenay and Williams 2004). The northern snakehead is an obligate air breather; it utilizes a suprabranchial organ and a bifurcate ventral aorta
that permits aquatic
and aerial respiration
(Ishimatsu and Itazaw 1981, Graham 1997). This unusual respiratory
system allows it to live outside of water for several days, where concern is that it might wriggle its way to other bodies of water or be transported by humans.
Note that only young of this species (not adults) may be able to move overland for short distances using wriggling motions (Courtenay and Williams 2004). The preferred habitats of this species are stagnant water with mud substrate and aquatic vegetation, or slow muddy streams; it is primarily piscivorous but is known to eat crustacean
s, other invertebrate
s, and amphibians (Okada 1960). They build spawning nests in aquatic vegetation and females discharge eggs
over the nest
, which are externally fertilized by males (Okada 1960).
Two subspecies are distinguished – Channa argus argus originating from China and Korea and Channa argus warpachowskii originating from eastern Russia.
The fish first appeared in U.S. news when an alert fisherman discovered one in a Crofton, Maryland
, pond in the summer of 2002. The snakehead fish was considered to be a threat to the Chesapeake Bay
watershed, and wary officials took action by draining the pond in an attempt to destroy the species. The action was successful, and two adult and over 100 small fish were found and destroyed. A man admitted having released two adults, which he had purchased from a New York market, into the pond
In 2004, nineteen northern snakeheads were captured in the Potomac River
, and it was later confirmed that they had become established (were breeding). They are somewhat limited to that stretch of the river and its local tributaries, upstream by the Great Falls
, and downstream by the salinity of Chesapeake Bay. Tests found that they are not related to northern snakeheads found in other waters in the region, alleviating some concern of their overland migration. Northern snakehead continue to be caught in the river as of 2007.
The northern snakehead has been found in three counties of Florida
, and may be established. Apparently non-established specimens have been found in Flushing Meadows-Corona Park
, New York
, two ponds in Philadelphia, Pennsylvania
, a pond in Massachusetts
, and reservoirs in California
and North Carolina
. In 2008, the northern snakehead was found in drainage ditches in Arkansas
, as a result of a commercial fish farming accident. It is feared that recent flooding allowed the species to spread into the nearby White River, which would allow an eventual population of the fish in the Arkansas
and Mississippi River
s.
In the summer of 2008 there was a confirmed infestation of the northern snakehead in Ridgebury Lake and Catlin Creek near Ridgebury, New York
. By August 2008, the New York State Department of Environmental Conservation
had collected a number of the native fish, and then poisoned the waters with CFT Legumine, a liquid rotenone
formulation. After the poisoning, the NYS D.E.C. had to identify, measure and additionally process the fish to adhere with Bureau of Fisheries procedures before disposal. The Treatment Plan was operated under several agents, and New York State Police
were placed on stand-by in case of protests of local residents of the area.http://www.dec.ny.gov/environmentdec/45498.html
A new concern is that this fish's spread is getting close to the Great Lakes
, which it may enter and disrupt that ecosystem.
When the snakehead was found in Crofton, the piscicide
Rotenone
was added to the three adjacent ponds. This method of containment killed all fish present in the water body to prevent the spread of the highly invasive snakehead. The chemical breaks down rapidly, and has a half life in water of one to three days.
Channidae
The Snakeheads are members of the freshwater perciform fish family Channidae, native to Africa and Asia. These elongated predatory fish are distinguished by a long dorsal fin, large mouth and shiny teeth. They breathe air with a suprabranchial organ, a primitive form of a labyrinth organ...
native to China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
, North Korea
North Korea
The Democratic People’s Republic of Korea , , is a country in East Asia, occupying the northern half of the Korean Peninsula. Its capital and largest city is Pyongyang. The Korean Demilitarized Zone serves as the buffer zone between North Korea and South Korea...
and South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
. In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, the fish is considered to be a highly invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
. In a well-known incident, several were found in a pond
Pond
A pond is a body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens, water features and koi ponds; all designed for aesthetic ornamentation as landscape or architectural...
in Crofton, Maryland in June 2002, which led to major media coverage and two movies about the incident, Snakehead Terror
Snakehead Terror
Snakehead Terror is a science fiction / horror film released in March 2004. It is one of two Syfy Channel films based on the snakehead fish incident in a Crofton, Maryland pond...
and Frankenfish
Frankenfish
Frankenfish is a 2004 creature horror movie dealing with genetically engineered fish in the bayou. The film was based on the snakehead fish incident in a Crofton, Maryland, pond...
.
Biology
Distinguishing features of the northern snakehead include a long dorsal finDorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
with 49-50 rays, anal fin with 31-32 rays, small anteriorly-depressed head, eye above the middle part of the upper jaw, large mouth extending well beyond the eye, villiform teeth in bands, large canine on the lower jaw and palatines, length up to 40 inches (1.0 m), with one report of 60 inches (1.5m), and weight up to 15 pounds (7 kg).
Coloration is a golden tan to pale brown, with dark blotches on the sides and saddle-like blotches across the back. Blotches toward the front tend to separate between top and bottom sections, while rear blotches are more likely to be contiguous. Coloration is nearly the same between juveniles and adults, which is unusual among snakeheads.
Coloration is similar to Channa maculata
Channa maculata
Channa maculata, the blotched snakehead, is a species of snakehead. It is native to southern China and northern Vietnam, but has been widely introduced to other countries, where it is an invasive species. Adults typically grow to a length of , but a maximum of has been recorded....
, but can be distinguished by two bar-like marks on the caudal peduncle (where the tail attaches): in Channa maculata, the rear bar is usually complete, with pale bar-like areas before and after, while in Channa argus, the rear bar is irregular and blotched, with no pale areas around it.
The Northern snakehead is a freshwater species and cannot tolerate salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
in excess of ten parts per thousand (Courtenay and Williams 2004). The northern snakehead is an obligate air breather; it utilizes a suprabranchial organ and a bifurcate ventral aorta
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
that permits aquatic
Aquatic respiration
Aquatic respiration is the process whereby an aquatic animal obtains oxygen from water.-Fish:In most fish respiration takes place through gills. Lungfish, however, possess one or two lungs...
and aerial respiration
Respiration (physiology)
'In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction...
(Ishimatsu and Itazaw 1981, Graham 1997). This unusual respiratory
Respiration (physiology)
'In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction...
system allows it to live outside of water for several days, where concern is that it might wriggle its way to other bodies of water or be transported by humans.
Note that only young of this species (not adults) may be able to move overland for short distances using wriggling motions (Courtenay and Williams 2004). The preferred habitats of this species are stagnant water with mud substrate and aquatic vegetation, or slow muddy streams; it is primarily piscivorous but is known to eat crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, other invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s, and amphibians (Okada 1960). They build spawning nests in aquatic vegetation and females discharge eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
over the nest
Nest
A nest is a place of refuge to hold an animal's eggs or provide a place to live or raise offspring. They are usually made of some organic material such as twigs, grass, and leaves; or may simply be a depression in the ground, or a hole in a tree, rock or building...
, which are externally fertilized by males (Okada 1960).
Two subspecies are distinguished – Channa argus argus originating from China and Korea and Channa argus warpachowskii originating from eastern Russia.
Channa argus as an invasive species
In many areas of the world, the snakehead fish is considered to be an important food fish. Due to its economic value, Channa argus has been introduced (intentionally or not) to several areas in the continental United States. In the U.S., the snakehead is a top-level predator. Introduction of Channa argus poses a substantial threat to native fish populations.The fish first appeared in U.S. news when an alert fisherman discovered one in a Crofton, Maryland
Crofton, Maryland
Crofton is a census-designated place and planned community in Anne Arundel County, Maryland, United States. Established in 1964, Crofton held its 40th birthday celebration in 2004....
, pond in the summer of 2002. The snakehead fish was considered to be a threat to the Chesapeake Bay
Chesapeake Bay
The Chesapeake Bay is the largest estuary in the United States. It lies off the Atlantic Ocean, surrounded by Maryland and Virginia. The Chesapeake Bay's drainage basin covers in the District of Columbia and parts of six states: New York, Pennsylvania, Delaware, Maryland, Virginia, and West...
watershed, and wary officials took action by draining the pond in an attempt to destroy the species. The action was successful, and two adult and over 100 small fish were found and destroyed. A man admitted having released two adults, which he had purchased from a New York market, into the pond
In 2004, nineteen northern snakeheads were captured in the Potomac River
Potomac River
The Potomac River flows into the Chesapeake Bay, located along the mid-Atlantic coast of the United States. The river is approximately long, with a drainage area of about 14,700 square miles...
, and it was later confirmed that they had become established (were breeding). They are somewhat limited to that stretch of the river and its local tributaries, upstream by the Great Falls
Great Falls of the Potomac River
The Great Falls of the Potomac River are located at the fall line of the Potomac River, upstream from Washington, D.C. Great Falls Park, operated by the National Park Service, is located on the southern banks in Virginia, while Chesapeake and Ohio Canal parkland is located along the northern banks...
, and downstream by the salinity of Chesapeake Bay. Tests found that they are not related to northern snakeheads found in other waters in the region, alleviating some concern of their overland migration. Northern snakehead continue to be caught in the river as of 2007.
The northern snakehead has been found in three counties of Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, and may be established. Apparently non-established specimens have been found in Flushing Meadows-Corona Park
Flushing Meadows
Flushing Meadows is an American short film by Larry Jordan, with director Joseph Cornell. The film is 8 minutes long, in color, 16mm, and silent....
, New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
, two ponds in Philadelphia, Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
, a pond in Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
, and reservoirs in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
and North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
. In 2008, the northern snakehead was found in drainage ditches in Arkansas
Arkansas
Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...
, as a result of a commercial fish farming accident. It is feared that recent flooding allowed the species to spread into the nearby White River, which would allow an eventual population of the fish in the Arkansas
Arkansas River
The Arkansas River is a major tributary of the Mississippi River. The Arkansas generally flows to the east and southeast as it traverses the U.S. states of Colorado, Kansas, Oklahoma, and Arkansas. The river's initial basin starts in the Western United States in Colorado, specifically the Arkansas...
and Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
s.
In the summer of 2008 there was a confirmed infestation of the northern snakehead in Ridgebury Lake and Catlin Creek near Ridgebury, New York
Ridgebury, New York
Ridgebury, New York is one of the eight Hamlets in the town of Wawayanda, New York. The hamlet and its township are located in Orange County, New York, approximately 65 miles north of New York City....
. By August 2008, the New York State Department of Environmental Conservation
New York State Department of Environmental Conservation
The New York State Department of Environmental Conservation is responsible for the conservation, improvement, and protection of natural resources within the U.S. state of New York. It was founded in 1970, replacing the previous Conservation Department...
had collected a number of the native fish, and then poisoned the waters with CFT Legumine, a liquid rotenone
Rotenone
Rotenone is an odorless chemical that is used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the roots and stems of several plants such as the jicama vine plant...
formulation. After the poisoning, the NYS D.E.C. had to identify, measure and additionally process the fish to adhere with Bureau of Fisheries procedures before disposal. The Treatment Plan was operated under several agents, and New York State Police
New York State Police
The New York State Police is the state police force of over 4,600 sworn Troopers for the state of New York. It was established on April 11, 1917 by the New York Legislature, in response to the 1913 murder of a construction foreman named Sam Howell in Westchester County, which at that time did not...
were placed on stand-by in case of protests of local residents of the area.http://www.dec.ny.gov/environmentdec/45498.html
A new concern is that this fish's spread is getting close to the Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
, which it may enter and disrupt that ecosystem.
When the snakehead was found in Crofton, the piscicide
Piscicide
A piscicide is a chemical substance which is poisonous to fish. The primary use for piscicides is to eliminate a dominant species of fish in a body of water, as the first step in attempting to populate the body of water with a different fish...
Rotenone
Rotenone
Rotenone is an odorless chemical that is used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the roots and stems of several plants such as the jicama vine plant...
was added to the three adjacent ponds. This method of containment killed all fish present in the water body to prevent the spread of the highly invasive snakehead. The chemical breaks down rapidly, and has a half life in water of one to three days.
Further reading
- Anonymous. 2005. 2005 World Record Game Fishes. International Game Fish Association, Dania Beach, FL. 400 pp.
- Courtenay W. R. Jr., and J. D. Williams. 2004. "Snakeheads (Pisces, Channidae).—A Biological Synopsis and Risk Assessment", U.S. Geological Survey Circular 1251, vi+143 pp.
- Ishimatsu, A., and Y. Itazaw. 1981. "Ventilation of the air-breathing organ in the snakehead Channa argus."—Japanese Journal of Ichthyology 28(3): 276–282.
- Graham, J. B. 1997. Air-breathing fishes: evolution, diversity, and adaptation. Academic Press, San Diego, California, xi + 299 pp
- Okada, Y. 1960. "Studies of the freshwater fishes of Japan, II, Special part".—Journal of the Faculty of Fisheries Prefectural University of Mie 4(3): 1–860.
External links
- InvadingSpecies.com
- Recognizing Northern Snakehead
- Fish or Foul: Snakeheads near Washington, D.C., and the people who love them
- snakeheads.org
- Northern Snakehead
- Species Profile- Northern Snakehead (Channa argus), National Invasive Species Information Center, United States National Agricultural LibraryUnited States National Agricultural LibraryThe United States National Agricultural Library is one of the world's largest agricultural research libraries, and serves as a National Library of the United States and as the library of the United States Department of Agriculture...
. Lists general information and resources for Northern Snakehead.