Description
Potentially Misidentifed Species- Channa marulius (Bullseye Snakehead), C. micropeltes (Giant Snakehead), and C. maculata, are native to Asia and have all been collected in North America, though only C. marulius, has established populations on the continent. Channa marulius, is locally established in southeast FL. A single specimen was caught in Baltimore Harbor, in September 2002. This fish was apparently dying and was apparently the result of a single prank release during the "snakehead" media furor of that summer. Specimens of C. micropeltes have been caught in ME, MA, RI, WI and MD. Locations of the 2 earlier MD collections were not given by Courtenay and Williams (2004). A single specimen of C. maculata was collected from the Charles River, Boston MA. All 3 of these species, unlike C. argus, are subtropical-tropical and unlikely to survive Chesapeake Bay winters (USGS Nonindigenous Aquatic Species Program 2004; Courtenay and Williams 2004).
Taxonomy
| Kingdom | Phylum | Class | Order | Family | Genus |
|---|---|---|---|---|---|
| Animalia | Chordata | Osteichthyes | Perciformes | Channidae | Channa |
Synonyms
Invasion History
Chesapeake Bay Status
| First Record | Population | Range | Introduction | Residency | Source Region | Native Region | Vectors |
|---|---|---|---|---|---|---|---|
| 2004 | Established | Expanding | Introduced | Regular Resident | East Asia | East Asia | Fisheries(Fisheries Accidental; Fisheries Intentional),Ornamental(Pet Release) |
History of Spread
Channa argus (Northern Snakehead) is native to Pacific river drainages of Asia, from the Amur basin on the Chinese-Siberian (Russia) border to upper tributaries of the Yangtze. It has been successfully introduced to other waters of China, freshwaters of Japan, and the Aral Sea basin of Kazakhstan, and unsuccessfully to the Moscow region of Russia (Courtenay and Williams 2004).
In North America, isolated specimens of Channa argus were collected in Spiritwood Lake, San Bernardino Mountains CA (1997), Volusia County FL, in the St. Johns River (2000), in a pond near Shrewsbury MA (2001), and in Lake Wylie, on the Catawba River NC (2002) (Courtenay and Williams 2004). A population was discovered in northeast AR in 2008, which is now established (USGS Nonindigenous Aquatic Species Program 2011).
The first confirmed established population of C. argus was discovered in the Chesapeake Bay watershed on May 14, 2002, in a small (1.8 ha) retention pond in Crofton MD, not far from the Little Patuxent River, when a 45 cm specimen was caught. In the following months, more than 1,000 juvenile fish were caught durng eradication efforts. The Snakehead story received intense nationwide media coverage, and became a widespread but short-lived cultural phenomenon, spawning cartoons, T-shirts, jokes, etc. On August 18th, the pond was treated with herbicides, in order to aid in detection of fish, and on Septermber 4th, the pond, together with 2 neighboring ponds was treated with rotenone to kill the fish. This treatment was effective- no additional C. argus have been seen in the pond (Dolin 2003; Courtenay and Williams 2004; Huslin 2002; Kobell and Thomson 2002; Thomson 2002).
In April-May 2004, in quick succession, 4 specimens of Channa argus were found in the Chesapeake Bay watershed. On May 26, 2004, a single fish was caught in Pine Lake, in Wheaton (MD) Regional Park, off Sligo Creek, a Potomac tributary in the Washington DC suburbs. The pond was drained, but no additonal snakeheads were found (Faranthold 2004). On May 7, a snakehead was caught in Little Hunting Creek, near Mount Vernon VA on the tidal Potomac River. On May 12, another specimen was caught across the river, near Marshall Hall MD, and on May 15, a third specimen was caught in the Potomac estuary near Mason Neck National Wildlife refuge, a few km downriver from the previous captures (Virginia Department of Fish and Game 2004; Whoriskey 2004). Two more fish were caught in the general area, in Pohick Bay, May 27, and on June 4th, in Dogue creek, near Mount Vernon (Washington Post 2004). By October 1st, 19 fish of varying sizes had been caught by anglers, including 3 egg-bearing females. On this date, a juvenile fish 7.5 cm long was found in a clump of hydrilla tangled in a boat trailer (Virginia Department of Game). Genetic analysis indicates that the fish from Crofton introduced in 2002, the fish from Pine Lake, Wheaton, and the fish captured in the Potomac, in 2004 have different haplotypes, and each represent different introductions. At least 7 separate haplotypes were identified in Northern Snakeheads recently caught in North America, 2 from the Potomac, two from established populations from PA, and a single fish from MA , indicating that multiple introductions have occurred at many locations in North America (Orrell and Weigt 2005).
In October 2005, after a heavy rain, a mass upstream movement of Northern Snakeheads was seen in Dogue Creek, Virginia. Local anglers caught at least 80 fish moving past the remains of a dam (Partlow 2005). A study of snakehead movements using radio tracking found that the fish preferred areas with heavy cover of submerged aquatic plants, especially Eurasian Watermilfoil (Myriophyllum spicatum, and moved into shallower water, and up creeks for spawning in early June. They moved into deeper water in winter (Lapointe et al. 2010). In February, 2006, a snakehead was caught in meshohaline waters of the Potomac, below Rt. 301 and above Colonial Beach, Virginia. in upper Machodoc Creek, at 7.9 ppt (USGS Nonindigenous Aquatic Species Program 2009). In 2010, fish were caught near Kinsale VA, in Hampton Hall Branch, near the mouth of the Potomac, at Kitts Point, at the mouth of St. Marys River, and near Scotland MD, on the open bay between the Potomac and St. Jeromes Creek, streams draining into the Potomac estuary near its mouth (USGS Nonindigenous Aquatic Species Program 2010), suggestive of dispersal through brackish water. In April 2011, a snakehead was caught at White's Ferry, about 56 km (35 miles) above the head of tide on the Potomac, the first capture above Great Falls. The Chesapake and Ohio canal is a possible vector for dispersal above the falls (Sharbell 2011). By 2015, snakeheads were seen regularly above the falls (Zausmer 2015). Based on sampling between 2010 and 2013, and on models of habitat preference and dispersal, Love et al. (2015) estimated that there were 21,279 adult Northern Snakeheads in the Potomac (Love et al. 2015).
In April-July of 2011, several catches of snakeheads were reported in the Bay outside the Potomac River, from St. Jeromes Creek to the Nanticoke River, and up the Bay to the Rhode and Northeast Rivers. These may have resulted from heavy winter and early spring rains which resulted in unusually low salinities in Chesapeake Bay, permitting the fish to disperse widely, although separate introductions are also possible. One fish was caught at Buzz's Marina, in St. Jerome's Creek, on May 3
(Tidalfish.com, http://www.tidalfish.com/forums/showthread.php/302886-Snakehead-caught-today-right-at-Buzz-s-Marina-docks), one near the mouth of the Patuxent, in Middle Creek, north of Solomons (7/10) (USGS Nonnidigenous Aquatic Species Program 2011); another on the Eastern Shore at Wetapquin, MD, in Tyaskin Creek, a tributary of the Nanticoke (6/8/2011, Maryland Department of Natural Resources 2011 http://dnr.maryland.gov/fisheries/fishingreport/). Two additonal fish were caught in nontidal Nanticoke tributaries in DE, one in Marshyhope Creek in July 2011, and one in Broad Creek in the fall of 2010 (WBOC News 7/22/2011, http://www.wboc.com/story/15131544/2-invasive-snakeheads-recently-caught-in-del-waterways). In March of 2012, a snakehead was caught on the Blackwater River (USGS Nonindigeneous Aquatic Species Program 2012). On July 14, one fish, 584 mm long, was caught in a seine in the Rhode River (Ruiz et al, unpublished data; Thomson 7/19/2011). One fish was caught at the head of the Bay, on the Northeast River, on April 17 (4/17/2011, http://dnr.maryland.gov/fisheries/fishingreport/). In July 2012, a Snakehead was caught in a tributary of the Rappahannock River, below Fredericksburg, Virginia, and by 2013, numerous catches were made, and the fish was considered established Nonindigeneous Aquatic Species Program 2013; (Dennen 2013). By May 2013, populations of C. argus appear to be established in the upper tidal Patuxent River, the Choptank, Nanticoke, and Wicomico Rivers, on the MD Eastern Shore, and the Rappahannock River (USGS Nonindigenous Aquatic Species Program 2013).
The likeliest sources of Channa argus in North America are Asian food markets, which frequently sell live imported fish. Snakeheads are highly prized as food in many Asian communities, and are also frequently believed to have medicinal properties (Courtenay and Williams 2004). The origin of the Crofton MD population was a release by a man who had ordered the fish from a New York market, as a remedy for a relative's illness. When the fish were no longer needed, and grew too big to keep, he discarded them in the pond. The Maryland Department of Natural Resources kept the man's name anonymous, and did not prosecute, since the man had violated no laws at the time of the act (Dolin 2003). We consider this introduction to be "accidental", since it was not done with apparent intent to start a population. The source of the later releases is not clear. Young snakeheads of various species are occasionally sold in the aquarium trade, because of their attractive markings and interesting behavior. However, Channa spp. are voracious, grow fast, and tend to quickly wear out their welcome (Courtenay and Williams 2004).
In July 20-23, 2004, 6 Channa argus were caught in Meadow Lake in FDR Park, Philadelphia, a marshy lake, connected by sloughs to the tidal Delaware River (Pennyslvania Fish and Boat Commission 2004). By 2011, C. argus were caught from Delaware tributaries on the outskirts of Trenton (Crystal Lake, Florence-Roebling) downriver to Wilmington DE (Nonesuch Creek, Wilmington Manor (USGS Nonindigenous Species Program 2012). In August 2011, adult fish and 'bucketfuls' of fry were caught in Becks Pond near Glasgow DE, in the drainage of the Christina River, a Delaware River tributary. Delaware conservation officers believe that the fish were deliberately stocked in the pond. (Montgomery 8/20/2011).
In 2005, a third introduced population was found in ponds in Flushing Meadows Corona Park, Queens, New York City. Thses fish have been found in several ponds and lakes in Queens, but have not entered the tidal waters of the Hudson River or Long Island Sound. Yet another population was found in the upper Hudson watershed, in lakes near Wayawanda NY, north of the Catskills in 2008 (USGS Nonidigenous Species Program 2016). An overview of the genetics of C. argus in North America found that the Chesapeake Bay animals were derived from one introduction in the Potomac, while the Delaware, and the upper and lower Hudson watershed populations were related to snakeheads bought in a Chinese market in New York City. This suggests that there were at least two separate introductions to the northeast US from Asia (Wegleitner et al. 2016).).
References- Courtenay and Williams 2004; Dolin 2002; Farenthold 2004; Farenthold and Partlow 2004;Huslin 2002; Kobell and Thomson 2002; Orrell and Weigt 2005; Partlow 2005; Pennyslvania Fish and Boat Commission 2004; Thomson 2002; Virginia Department of Game and Inland fisheries 2004a; Virginia Department of Game and Inland fisheries 2004b; Whoriskey 2004
Invasion Comments
At least 2 specimens of another snakehead, Channa micropeltes (Giant Snakehead) have been collected from the Chesapeake Bay watershed, two from freshwater drainages in MD in 2000-2001. Channa micropeltes is a tropical species, native to southeast Asia and India, and is unlikely to survive in temperate North America (Courtenay and Williams 2004). Channa marulius (Bullseye Snakehead), another tropical species is locally established in Broward County FL (Courtenay and Williams 2004). One fish was caught in Baltimore Inner Harbor. The Baltimore specimen was seen struggling at the surface on September 6, 2002, and was netted by a crabber. This fish was clearly released as a prank during the snakehead furor of the summer of 2002, and probably would not have survived long in the brackish water (Dolin 2002). Consequently, we have not made a separate database entry for this species
Ecology
Environmental Tolerances
| For Survival | For Reproduction | |||
|---|---|---|---|---|
| Minimum | Maximum | Minimum | Maximum | |
| Temperature (ºC) | 0.0 | 35.0 | ||
| Salinity (‰) | 0.0 | 15.0 | 0.0 | |
| Oxygen | anoxic | |||
| pH | ||||
| Salinity Range | fresh-meso |
Age and Growth
| Male | Female | |
|---|---|---|
| Minimum Adult Size (mm) | 300.0 | 300.0 |
| Typical Adult Size (mm) | ||
| Maximum Adult Size (mm) | 850.0 | 850.0 |
| Maximum Longevity (yrs) | ||
| Typical Longevity (yrs |
Reproduction
| Start | Peak | End | |
|---|---|---|---|
| Reproductive Season | |||
| Typical Number of Young Per Reproductive Event |
|||
| Sexuality Mode(s) | |||
| Mode(s) of Asexual Reproduction |
|||
| Fertilization Type(s) | |||
| More than One Reproduction Event per Year |
|||
| Reproductive Startegy | |||
| Egg/Seed Form |
Impacts
Economic Impacts in Chesapeake Bay
Channa argus (Northern Snakehead) has not yet had a significant economic impact within the tidal waters of Chesapeake Bay. However, the eradication effort in Crofton MD, in 2002, cost the Maryland Department of Natural Resources at least $110,000 (Courtenay and Williams 2004). In 2004, draining of a pond in Wheaton MD, and continued monitoring and education efforts in MD and VA are likely to require additional state resources. If a population is established in the Potomac estuary, the cost , as well as the ecological impacts, will probably preclude any eradication attempt. More feasible responses include education efforts to limit the population growth of the fish (telling fishermen to keep or kill Snakeheads) and enforcement and education efforts to limit further spread.
The wave of publicity during the "Snakehead Scare" did generate some positive publicity for the general invasive species issue, as well as some local business in Crofton due to worldwide media coverage. One family made $12,000 selling "Snakehead" T-shirts (Dolin 2002).
Establishment of C. argus in freshwater tributaries of Chesapeake Bay could result in increased predation on anadromous fishes such as Alosa sapidissima (American Shad) and A. pseudoharengus (Alewife, River Herring), and the young of economically important sport fishes, such as Micropterus salmoides (Largemouth Bass), Ictalurus spp. (Catfishes), Morone americana (White Perch) and M. saxatilis (Striped Bass). Channa argus (Northern Snakehead) could also compete with adults of the predatory sport fishes, or have wider, unpredictable effects on the estuarine ecosystem, through alteration of foodwebs (Courtenay and Williams 2004).
Modelling indicates that the current impact of Channa argus (Northern Snakehead) on the sport fishery for Largemouth Bass (Micropterus salmoides), due to predation on juveniles, is small, but is predicted to increase as the population grows (Love and Newhard 2012).
References- Courtenay and Williams 2004; Dolin 2002; Love and Newhard 2012
Economic Impacts Outside of Chesapeake Bay
Channa argus (Northern Snakehead) is a highly prized food fish in Asia and in Asian-American communities, and is also believed to have medicinal properties. Consequently, there is considerable economic pressure to import or rear this fish. In 1997-2002, 51,000 live or dead Channa spp, with a total value of $133,000 were imported into the US. Before 2002, its possession and/or sale was banned in 14 states, and 9 additional states including MD, VA, and PA subsequently banned this and other Channa species. However, even in states where it is banned, this fish still has been found in Asian markets (Courtenay and Williams 2004). A federal regulation, as passed in July 2002, classifies Channidae as "injurious wildlife" under the Lacey Act prohibits importation or interstate transport of live snakeheads (Courtenay and Williams 2004).
Courtenay and Williams (2004) consider fishes of the family Channidae (snakeheads) to pose a threat of "medium" and "moderately certain" economic impact through predation on or competition with economically important fishes, and through alteration of foodwebs. The cost of eradication, where it is possible, is also a substantal burden to state governments. The successful eradication in Crofton MD cost $110,000 to eliminate a population in a 1.8 ha pond (Courtenay and Williams 2004). Eradication in a larger lake or river system would probably cost millions and have major economic and environmental impacts.
References- Courtenay and Williams 2004; Dolin 2002
Ecological Impacts on Chesapeake Native Species
Channa argus (Northern Snakehead) has not yet had any direct impacts on aquatic ecosystems in the Chesapeake Bay region, or in North America, since no populations are known to be established. However, this species is regarded with great concern as a potential invader. Snakeheads (Channidae), as a group, are known as voracious predators on fishes, amphibians and crustaceans (Courtenay and Williams 2004; Dolin 2003). They are considered to pose a threat to threatened and endangered species and to alter communities, through predation. Their potential to transfer new parasites or diseases to native fishes is unknown (Courtenay and Williams 2004).
Stomach contents of 219 C. argus in the Potomac were dominated by Fundulus diaphanus (27%), but included a wide range of other species, including Morone americana (White Perch), Lepomis gibbosus (Pumpkinseed Sunfish), L. macrochirus (Bluegill and 11 other fish species, plus frogs and crayfish (Odenkirlk 2006, cited by Northern Snakehead Working Group 2007).
Efforts to eradicate C. argus have had an impact on native communities in the ponds in Wheaton and Crofton MD, where whole fish communities were killed through rotenone poisoning or draining (Dolin 2003; Farenthold 2004). Effects on native wildlife and ecosystems are likely to be a major factor hindering eradication in larger bodies of water.
References- Courtenay and Williams 2004; Dolin 2003; Farenthold 2004
Ecological Impacts on Other Chesapeake Non-Native Species
Channa argus (Northern Snakehead) isnot yet known to be established in the Chesapeake Bay region. It is a potential predator on introduced fishes, crayfishes, and turtles in the Chesapeake Bay region. Among the more likely non-native prey are Carassius auratus (Goldfish), young Cyprinus carpio (Common Carp), young Ictalurus spp. (Channel and Blue Catfish) (Lepomis macrochirus (Bluegill), and young Micropterus salmoides (Largemouth Bass), Orconectes virilis (Virile Crayfish) and young Trachemys scripta. Competition with larger predators, such as Ictalurus spp. and M. salmoides is also possible. In experiments, Channa argus had high rates of predation on small (<100 mm) age 0 Largemouth Bass (Micropterus salmoides). Current rates of co-occurrence in MD waters (10.6% of stations sampled) and estimated rates of predation are small (3.8 % per year), but are predicted to increase as Snakehead populations increase (Love and Newhard 2012).
Rates of co-occurrence with Micropterus salmoides (Largemouth Bass) are still small, (10.6% of stations sampled), but as populations increase, overlap of food and nest-building sites is likely (Love and Newhard 2012).
References- Courtenay and Williams 2004; Dolin 2003; Farenthold 2004; Saylor et al. 2012
References
Courtenay, Walter R., Jr.; Williams, James D. (2004) Snakeheads (Pisces, Channidae)- A biological synopsis and risk assessment., United States Geological Survey Circular 1251: 1-1515/15/2013 Snakeheads slithering up Rappahannock. http://news.fredericksburg.com/newsdesk/2013/05/15/snakeheads-slithering-up-rappahannock/
Dolin, Eric J. (2003) Snakehead: A fish out of water., , Washington, DC. Pp.
Fahrenthold, David A; Partlow, Joshua (Oct. 5, 2004) Baby snakehead is no bundle of joy., Washington Post None: B-1
May 4, 2004 Confidence grows that Wheaton Lake is "Snakehead-free".. Web address: http://www.washingtonpost.com/wp-dyn/articles/A64387-2004May3.html
Gascho Landis, Andrew M.; Lapointe, Nicholas; Angermeir, Paul L. (2011) Individual growth and reproductive behavior in a newly established population of northern snakehead (Channa argus), Potomac River USA, Hydrobiologia 661: 123-121
Gascho Landis, Andrew M.; Lapointe, Nicolas W.R. (2010) First record of a Northern Snakehead (Channa argus Cantor) nest in North America, Northeastern Naturalist 17: 325-332
Herborg, Lieff-Matthias; Mandrak, Nicoholas; Cudmore, Betty C.; MacIsaac, Hugh J. (2008) Comparative distribution and invasion risk of snakehead (Channidae) and invasive carps (Cyprinidae) species in North America., Canadian Journal of Fisheries and Aquatic Science 64: 1723-1735
July 12, 2002 Snakeheads' luck put pond in the soup.. Washington, Post, A1
Jiao, Yan; . Lapointe, Nicolas W.R; Angermeier, Paul L.; Murphy, Brian R. (2009) Hierarchical demographic approaches for assessing invasion dynamics of non-indigenous species: An example using northern snakehead (Channa argus), Ecological Modelling 220: 1681-1689
Kobell, Rona; Thomson, Candus (11-21-2002) State shares victory over snakehead fish., Baltimore Sun None: None
Landis, Andrew M. Gascho; W. R. Lapointe, Nicolas; Angermeier, Paul L. (2012) Individual growth and reproductive behavior in a newly established population of northern snakehead (Channa argus), Potomac River, USA, Hydrobiologia 661: 123-131
Lapointe, N. W. R.; Odenkirk, J. S.; Angermeier, P. L. (2013) Seasonal movement, dispersal, and home range of Northern Snakehead Channa argus (Actinopterygii, Perciformes) in the Potomac River catchment, Hydrobiologia 709: 73-87
Lapointe, N. W. R.; Thorson, J. T.; Angermeier, P. L. (2010) Seasonal meso- and microhabitat selection by the northern snakehead (Channa argus) in the Potomac river system, Ecology of Freshwater Fish 19: 566-577
Love, Joseph W.; Newhard, Joshua (2012) Will the expansion of northern snakehead negatively affect the fishery for largemouth bass in the Potomac River (Chesapeake Bay)?, North American Journal of Fisheries Management 32: 859-868
Love, Joseph W.; Newhard, Joshua J.; Greenfield, Brett (2015) A geospatial approach for estimating suitable habitat and population size of the invasive northern snakehead, Journal of Fish and Wildlife Management 6: 145-157
Montgomery, Jeff (2011) A fishy case, Wilimington (DE) News-Journal None: None
Northern Snakehead Working Group (2007) National control and management plan for the Northern Snakehead (Channa argus) (Draft), None , Washington DC. Pp. 1-32
Odenkirk, John; Owens, Steve (2005) Northern snakeheads in the tidal Potomac River system, Transactions of the American Fisheries Society 134: 1605-1609
Odenkirk, John; Owens, Steve (2007) Expansion of a northern snakehead population in the Potomac River system, Transactions of the American Fisheries Society 136: 1633-1639
Orrell, Thomas M.; Weigt, Lee (2005) The Northern Snakehead Channa argus, a non-indigenous fish in the Potomac River, U.S.A., Proceedings of the Biological Society of Washington 118: 407-415
Owens, Stephen J.; Odenkirk, John S.; Greenlee, robert (2007) Northern snakehead movement and distribution in the tidal Potomac River system, Proceedings of the Annual Conference of the Southeast Association of Fish and Wildlife Agencies 62: 161-167
Partlow, Joshua (October 11, 2005) In rain's wake, a deluge of snakeheads., Washington Post None: B1, B4
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Poulos, Helen M.; Chernoff, Barry; Fuller, Pam L.; Butman, David (2011) Ensemble forecasting of potential habitat for three invasive fishes, Aquatic Invasions 7: corrected proof
Sharbell, Andrew (4/29/2011) Snakehead caught near White's Ferry, Loudon Times-Mirror None: None
Thomson, Candus (6/22/2002) It lurks in Crofton waters, Baltimore Sun :
Thomson, Candus (7/19/2011) Invasive snakehead is found in river near Annapolis, Baltimore Sun None: A2
2003-2024 Nonindigenous Aquatic Species Database. Gainesville, FL. http://nas.er.usgs.gov
May 18th, 2004 Tournament fisherman turns in fourth snakehead.. Web address: http://www.dgif.virginia.gov/newsroom/pr-051804-Snakehead.html
May 18, 2004 3rd Snakehead taints the Potomac.. http://www.washingtonpost.com/ac2/wp-dyn/A34540-2004May17?language=printer