Channa argus

Invasion History

First Non-native North American Tidal Record: 2003
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 2003

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General Invasion History:

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 (Lever 1996; Courtenay and Williams 2004). In the United States, scattered released of Northern Snakeheads have occurred in 7 states, from 1997 (California) to 2017 (Connecticut). Snakehead populations are now established in the Chesapeake (2004), Delaware River (2000), Hudson (New York City area non-tidal tributaries; 2005), and Arkansas-Mississippi tributaries (2008)  (USGS Nonindigenous Aquatic Species Program 2023). This fishes disperses rapidly on its own, and with human assistance. 

The first confirmed population of Channa argus in North America  was discovered in the Chesapeake Bay watershed on May 14, 2002, in a small retention pond in Crofton Maryland, not far from the Little Patuxent River, when a 45 cm specimen was caught. The snakehead story received intense nationwide media coverage and officials treated the pond with rotenone to eradicate the species. More than 1,000 juvenile fish were caught during eradication efforts. This treatment was effective as no additional C. argus were seen in the pond (Dolin 2003; Courtenay and Williams 2004).  However, in April-May 2004 in quick succession, 4 specimens of Channa argus were found in Potomac tributaries, and in 2004–2005 many juvenile and adult fish were caught in the tidal Potomac and its tributaries. In 2005, mass movements of juvenile snakeheads occurred during a period of heavy rains, permitting snakeheads to spread from the Potomac, the Patuxent, Nanticoke, and Rappahannock Rivers, and tributaries on the Upper Bay. By 2010, snakeheads had spread to the mouth of the Potomac, by 2011 had entered the Patuxent River, and by 2012, they were found in the Nanticoke and Blackwater rivers on the Eastern shore.  By 2013, they have been found in most of the Maryland tributaries, and colonized the Susquehanna River above Conowingo Dam in Pennsylvania, and the Potomac river well above Great Falls (USGS Nonindigenous Aquatic Species Program 2013; Dennen 2013). By May 2013, populations of Northern Snakehead appear to be established in the upper tidal Patuxent River, the Choptank, Nanticoke, and Wicomico Rivers, on the Maryland Eastern Shore, and the Rappahannock River (USGS Nonindigenous Aquatic Species Program 2013). This fish is now found in all the tidal watersheds of the Maryland portion of the Chesapeake Bay (Love and Newhard 2015; USGS Nonindigenous Species Database 2023). In Virginia, it reached the Rappahannock River in 2012 (USGS Nonindigenous Aquatic Species Database 2023). While natural dispersal seems to have accounted for most of the spread, scattered inland records are probably due to human releases.

In July 20–23, 2004, six Channa argus were caught in Meadow Lake in FDR Park, Philadelphia, a marshy lake, connected by sloughs to the tidal Delaware River (Pennsylvania 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 .  In 2019 adult fish and fry were reported from the Delaware Water Gap, and from upper Delaware waters in New York state (USGS Nonindigenous Species Database 2023).

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 Maryland 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 (Dolin 2003). 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 introductions to the northeast US (Wegleitner et al. 2016).

A population of Northern Snakehead was discovered in northeast Arkansas in 2008, which is now established and spreading in tributaries of the lower Arkansas River, reaching from Missouri, and Mississippi to Louisiana. Known scattered records include mostly individual fish from California, Connecticut, Florida, Georgia, Illinois, Massachusetts and North Carolina (USGS Nonindigenous Aquatic Species Program 2023).

North American Invasion History:

Invasion History on the East Coast:

The first confirmed established population of the Northern Snakehead on the East Coast was discovered when a 45 cm specimen was caught on May 14, 2002, in a small (1.8 ha) retention pond in Crofton Maryland, not far from the Little Patuxent River. In the following months, more than 1,000 juvenile fish were caught during 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 September 4th, the pond, together with 2 neighboring ponds was treated with rotenone to kill the fish. This treatment was effective—no additional snakeheads 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 Northern Snakehead 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 additional snakeheads were found (Fahrenthold 2004). On May 7, a snakehead was caught in Little Hunting Creek, near Mount Vernon, Virginia on the tidal Potomac River. On May 12, another specimen was caught across the river, near Marshall Hall Maryland, and on May 15, a third specimen was caught in the Potomac estuary near Mason Neck National Wildlife refuge, a few kilometers 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 and Inland Fisheries 2004). 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; two from the Potomac, two from established populations from Pennsylvania, and a single fish from Massachusetts 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 Virginia, in Hampton Hall Branch, near the mouth of the Potomac, at Kitts Point, at the mouth of St. Marys River, and near Scotland Maryland, on the open bay between the Potomac and St. Jeromes Creek, and in 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 Chesapeake and Ohio canal is a possible vector for dispersal above the falls (Sharbell 2011). By 2015, snakeheads were regularly occurring above Great Falls (Zausmer 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 Nonidigenous Aquatic Species Program 2011); another on the Eastern Shore at Wetipquin, Maryland, in Tyaskin Creek, a tributary of the Nanticoke (6/8/2011, Maryland Department of Natural Resources 2011 http://dnr.maryland.gov/fisheries/fishingreport/). Two additional fish were caught in nontidal Nanticoke tributaries in Delaware, one in Broad Creek in the fall of 2010 and one in Marshyhope Creek in July 2011 (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 Nonindigenous 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. By 2013, numerous catches were made, and the fish was considered established (USGS Nonindigeneous Aquatic Species Program 2013; Dennen 2013). By May 2013, populations of Northern Snakehead 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. One recent paper predicted that Northern Snakehead would colonize the entire Chesapeake watershed in 52 years (Love and Newhard, 2018). This fish is now found in all the tidal watersheds of the Maryland portion of the Chesapeake Bay (Love and Newhard 2018), and in Potomac and Rappahannock Rivers, with scattered records in the Pamunkey River, and the Poquoson River, near Lynnhaven (USGS Nonindigenous Aquatic Species Program 2023).

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 Maryland 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 often wear out their welcome (Courtenay and Williams 2004).

In July 20–23, 2004, 6 Northern Snakeheads were caught in Meadow Lake in FDR Park, Philadelphia, which is a marshy lake, connected by sloughs to the tidal Delaware River (Pennsylvania Fish and Boat Commission 2004). By 2011, Northern Snakeheads were caught from Delaware tributaries on the outskirts of Trenton (Crystal Lake, Florence-Roebling) downriver to Wilmington, Delaware (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, Delaware, 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. These 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, New York, north of the Catskills in 2008 (USGS Nonindigenous Species Program 2016). This upper Hudson basin population has been eradicated (Resh et al. 2018). 

Invasion History Elsewhere in the World:

One Northern Snakehead was caught in Burnham Harbor, Chicago, Lake Michigan (2004, USGS Nonindigenous Aquatic Species Program 2018). Geographic modeling predicts that the Northern Snakehead could colonize much of the Great Lakes based on temperature, but would be limited by habitat (shallow vegetated areas) (Kramer et al. 2017). In Asia, the Northern Snakehead was introduced to the Aral Sea basin (about 45º N) in the early 1960s, establishing its presence in the Amu Darya, Syr Darya, and Kashka-Dar’ya rivers of Kazakhstan, Uzbekistan, and Turkmenistan (Courtenay and Williams 2004).

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Description

Snakeheads (Channidae) are freshwater fishes distinguished by their elongated snake-like bodies, and flattened heads with dorsolateral eyes and large plate-like scales (cephalic plates). The nostrils are anterior and tubular. The dorsal and anal fins are elongated, and supported only by rays. The pelvic fins are jugular, located beneath the pectoral fins. All the species have suprabranchial chambers used for aerial respiration (Courtenay and Williams 2004).  The Northern Snakehead (Channa argus) has 49–54 dorsal rays and 32–38 anal rays. Fish mature at ~300 mm, and reach a maximum length of 850 mm. The surface of the lower jaw is unscaled (Courtenay and Williams 2004; Froese and Pauly 2018). The color is pale brown or tan, with irregular dark brown blotches, bordered with black. Two dark stripes extend from the eye to the edge of the operculum. Males have a broader head than females. Young fish have a similar color pattern to adults. Northern Snakeheads can darken their bodies until they look almost completely black (Courtenay and Williams 2004).

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Taxonomy

Ecology

General:

The Northern Snakehead (Channa argus) has a wide native range from southeast Siberia to central China, in cold-temperate to warm-temperate climates. It tolerates a temperate range from 0 to 30 °C (Courtenay and Williams 2004). While it is a freshwater fish, it can tolerate salinities of 15–18 PSU for short periods, but can survive for 30+ days at 10 PSU (Northern Snakehead Working Group 2007). Heavy winter and spring rains in 2011–2013 may have helped Northern Snakeheads to disperse from the Potomac to other Chesapeake tributaries, including the upper Bay, the Patuxent and Nanticoke Rivers (Love and Newhard 2015). While fish can be dispersed downstream by rain, juvenile fish have also shown mass upstream movements triggered by heavy rainfall. The Northern Snakehead is often found in shallow, stagnant vegetated pools and slow muddy streams, but also occurs in lakes, rivers, and reservoirs. They are obligate air-breathers, and can tolerate anoxia, but have only very limited ability to move overland. This fish is a predator. Postlarvae feed on zooplankton, juveniles on small crustaceans and fish larvae, while adults feed on other fishes, frogs, crustaceans, and aquatic insects (Courtenay and Williams 2005). Prey in the Potomac consisted of wide range of fishes, but was dominated by sunfishes (Centrarchidae), minnows (Cyprinidae) and killifishes (Fundulidae). There is a substantial dietary overlap with the Largemouth Bass (Micropterus salmoides), also introduced, and a major sportfish (Saylor et al. 2012).

Food:

Fishes, crayfishes., invertebrates

Consumers:

Humans, birds, mammals

Competitors:

Miacropterus salmoides (Largemouth Bass)

Trophic Status:

Carnivore

Carn

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Habitats

General Habitat	Fresh (nontidal) Marsh	None
General Habitat	Grass Bed	None
General Habitat	Coarse Woody Debris	None
General Habitat	Swamp	None
General Habitat	Nontidal Freshwater	None
General Habitat	Tidal Fresh Marsh	None
General Habitat	Unstructured Bottom	None
General Habitat	Canals	None
Salinity Range	Limnetic	0-0.5 PSU
Salinity Range	Oligohaline	0.5-5 PSU
Salinity Range	Mesohaline	5-18 PSU
Tidal Range	Subtidal	None
Vertical Habitat	Nektonic	None

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Life History

The Northern Snakehead (Channa argus) is a freshwater fish. Males have broader heads than females. Adults mature at about 300 mm and 2–3 years of age. Females carry 1300 to 50,000 eggs, increasing with length. Spawning occurs in the Potomac from April through August at 19–30 °C, but peaks at 26 °C (Courtenay and Williams 2005; Gascho Landis et al. 2012). Adults clear a nest about 1 m in diameter, in an area of submerged vegetation, clipping stems which float at the surface. The eggs are released and float into the mat of vegetation above the nest. Both sexes guard the nest, swimming slowly in circles. The eggs take about 12 hours to hatch. The fry remain near the nest for about 2 weeks. By about 12 days to 4 weeks and a length of 6–20 mm, the fry move an increasing distance from the nest as a school, but continued to be guarded by one or more parent. Adults live for 8 years or more, and reach a length of about 850 mm (Courtenay and Williams 2005; Gascho Landis and Lapointe 2010; Gascho Landis et al. 2011).

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Tolerances and Life History Parameters

Minimum Temperature (ºC)	0	Northern Snakehead Working Group 2007
Maximum Temperature (ºC)	31	Northern Snakehead Working Group 2007
Minimum Salinity (‰)	0	This is a freshwater fish.
Maximum Salinity (‰)	15	Short-term tolerance was 15-18 PSU when salinity raised by 1 PSU per day. At 24 C, mortality began at 10 PSU in 10-12 days, but at 15-20 C, fish survived 30+ days at 10 PSU (Northern Snakehead Working Group 2007).
Minimum Dissolved Oxygen (mg/l)	0	Channa argus is an obligate air-breather as an adult and can survive at very low oxygen levels (Courtenay and Williams 2004).
Minimum Reproductive Temperature	18	Courtenay and Williams 2004
Maximum Reproductive Temperature	30	Courtenay and Williams 2004; Gascho and Landis et al. 2012
Minimum Reproductive Salinity	0	None
Minimum Length (mm)	300	Courtenay and Williams 2004
Maximum Length (mm)	850	Courtenay and Williams 2004
Broad Temperature Range	None	Cold Temperate-Warm Temperate
Broad Salinity Range	None	Nontidal Limnetic-Mesohaline

General Impacts

Northern Snakeheads (Channa argus) are a valuable food and sport fish in their native Asia and in Asian-American communities and are 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 after 2002. However, even in states where it is banned, this fish still has been found in Asian markets (Courtenay and Williams 2004). A federal regulation, passed in July 2002, classifies Channidae as "injurious wildlife" under the Lacey Act, and prohibits importation or interstate transport of live snakeheads (Courtenay and Williams 2004).

In North America they have been illegally imported but are also developing a local reputation as delicious food fish and an attractive target for fishers and bow-hunters. At the same time, they have been regarded as a threat to native fish populations and aquatic ecosystems as an exotic predator. State fisheries agencies have spent considerable time and money in monitoring the spread of Northern Snakeheads in local waters and educating the fishing population to prevent new introductions (Dolin 2002; Courtenay and Williams 2004). As the Northern Snakehead has become established and spread, its biology and impacts are better known (Lapointe et al. al. 2011; Gascho Landis et al. 2012; Lapointe et al. al. 2012; Love and Newhard 2012; Saylor et al. 2012). At the same time, the popularity of the snakehead with the fishing community has increased (Fears 2012; Fears 2013), increasing the risk of illegal releases.

Economic Impacts-

The Northern Snakehead is extensively fished and widely cultured in China in rice paddies, ponds, and reservoirs. This fish was briefly cultured in Arkansas, until rearing was prohibited by the Arkansas Fish and Game Commission. 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 food webs. The cost of eradication, where it is possible, is also a substantial burden to state governments. In the United States, the focus of the federal and state governments has been on threats to native species, ecosystems, and established fisheries. Government efforts have involved eradication of populations where possible, enforcing regulations to prevent spread of the fish, and education of the fishing public (Courtenay and Williams 2004). When established populations were discovered in the Potomac and elsewhere, people caught the fish, first as a novelty, and then as sport.

Fisheries-

When first discovered in Maryland, Northern Snakeheads were publicized as vicious predators, capable of moving over land and surviving in foul waters. The eradication of the first discovered population in Crofton Maryland, 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, Maryland acquired additional state resources. After an established population was discovered in the Potomac, control efforts shifted education efforts to limit the population growth of the fish (requiring fishermen to keep or kill Snakeheads) and enforcement and education efforts to limit further spread (Maryland Department of Natural Resources 2018). As Snakeheads became established in the Potomac, people recognized them as an exciting gamefish, with the added benefits of removing an invasive species. Tournaments were organized, and bowhunters found the fish to be an interesting target (Fears 2012). Restaurants promoted snakehead as a novelty, with environmental benefits, but also as a desirable food fish (Fears 2013).

Potential negative impacts of the establishment of the Northern Snakehead in freshwater tributaries of Chesapeake Bay motivated research on the basic biology of the fish, including habitat preference and movements (Owens et al. 2007; Lapointe et al. 2012; Lapointe et al. 2013; Love et al. 2013), reproduction (Gascho Landis et al. 2012), and feeding (Saylor et al. 2012). Modeling indicates that the current impact of Northern Snakehead (Channa argus) 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).

Ecological Impacts-

The initial discovery of Northern Snakeheads in Crofton, Maryland prompted a wave of publicity, based on the fish's reputation as a vicious predator, and exaggerating its ability to move overland (Dolin 2003). However, the introduction of a large predator, exotic to the continent, promoted serious concern. In addition to predation, the transmission of exotic diseases and parasites is possible (Courtenay and Williams 2004). The spread of the Northern Snakehead through the Chesapeake Bay watershed has been surprisingly rapid. It has colonized an average of 2.7 sub-watersheds per year and moved well above the head of tide in many tributaries. It has been estimated to colonize the whole Chesapeake watershed in about 52 years (Love and Newhard 2018). As it moves through the watershed, it poses a threat to rare, threatened, and endangered species with limited ranges.

Predation-

In the Potomac estuary, prey of the Northern Snakehead in the Potomac consisted of a wide range of fishes, but was dominated by sunfishes (Centrarchidae), minnows (Cyprinidae) and killifishes (Fundulidae). The diet had substantial overlap with the Largemouth Bass (also an introduced species). So far, it appears to be much more piscivorous than the introduced Largemouth Bass or the native Yellow Perch (Perca flavescens), but this may represent opportunistic feeding (Saylor et al. 2012). As this fish spreads to more remote parts of the watershed, the Northern Snakehead may impact rarer, more isolated species.

Competition-

 The Northern Snakehead had a substantial overlap with the introduced Largemouth Bass in the Potomac estuary but consumed fewer invertebrates. Saylor et al. (2012) found limited evidence for competition. However, as populations of the snakehead increase, overlap of food and nest-building sites is likely (Love and Newhard 2012).

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Regional Impacts

M130	Chesapeake Bay		Ecological Impact	Predation
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).
M130	Chesapeake Bay		Ecological Impact	Competition
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).
M130	Chesapeake Bay		Economic Impact	Fisheries
Modeling 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). Sport fishing for snakeheads by hook-and-line, and by bow-hunting, has been promoted in tournaments (du Lac 2012; Fears 2012). Local restaurants have been cooking serving snakeheads, as a novelty, but also as good eating (Thomson 2011). State regulations require that fish be killed when caught, and not be transported alive.
DE	Delaware		Economic Impact	Fisheries
The Northern Snakehead is popular with sport fishermen.  Fishermen are required to kill them when caught (Delaware Department of Natural Resources and Recreation 2023,  https://fishspecies.dnrec.delaware.gov/FishSpecies.aspx?habitat=1&species=43)
M090	Delaware Bay		Economic Impact	Fisheries
The Northern Snakehead is popular with sport fishermen.  Fishermen are required to kill them when caught (Delaware Department of Natural Resources and Recreation 2023,  https://fishspecies.dnrec.delaware.gov/FishSpecies.aspx?habitat=1&species=43); The New Jersey Fish and  Wildlife website lists only 4 catches between 2014 and 2018 ( https://www.nj.gov/dep/fgw/pdf/delriver/artdel_sp_no_snakehead.pdfi).  Fishermen are also required to kill them in Pennsylvaniahttps://www.fishandboat.com/Fishing/All-About-Fish/Catch-PA-Fish/Pages/Snakehead.aspx )
MD	Maryland		Economic Impact	Fisheries
Fisheries concerns with the Northern Snakehead (Channa argus) involve complications of the introduction of an attractive food and gamefish, which is also a potential predator and competitor with established gamefish, some of which are also non-native, but long-established (e.g., Largemouth Bass, Micropterus salmoides).  Management of this species involves  conflicting issues of conservation and economics. States require or encourage killing of all snakeheads, but an increasing fishermen value the sporting aspects of the fish, and favor catch-and-release,  These conflicts are likely to increase over time (Orth et al. 2010).
MD	Maryland		Ecological Impact	Predation
Prey of Northern Snakeheads in the Potomac River were predominantly fishes (97%, led by Bluegills (Lepomis macrochirus, introduced) and killifishes (Fundulus spp.).  Larger adult fishes showed a preference for Yellow Perch (Perca flavescens, native). Their diet overlapped with another introduced predator, Largemouth Bass (Micropterus salmoides), but the bass showed a stronger preference for crayfishes. (Saylor et al. 2012).
NJ	New Jersey		Economic Impact	Fisheries
An official New Jersey website (https://www.nj.gov/dep/fgw/pdf/delriver/artdel_sp_no_snakehead.pdf) lists only 4 snakeheads caught from2014 to 2018, but fishing websites indicate and active sport fishery,
VA	Virginia		Economic Impact	Fisheries
Fisheries concerns with the Northern Snakehead (Channa argus) involve complications of the introduction of an attractive food and gamefish, which is also a potential predator and competitor with established gamefish, some of which are also non-native, but long-established (e.g., Largemouth Bass, Micropterus salmoides).  Management of this species involves  conflicting issues of conservation and economics. States require or encourage killing of all snakeheads, but an increasing fishermen value the sporting aspects of the fish, and favor catch-and-release,  These conflicts are likely to increase over time (Orth et al. 2010).
VA	Virginia		Ecological Impact	Predation
Prey of Northern Snakeheads in the Potomac River were predominantly fishes (97%, led by Bluegills (Lepomis macrochirus, introduced) and killifishes (Fundulus spp.).  Larger adult fishes showed a preference for Yellow Perch (Perca flavescens, native). Their diet overlapped with another introduced predator, Largemouth Bass (Micropterus salmoides), but the bass showed a stronger preference for crayfishes. (Saylor et al. 2012).
PA	Pennsylvania		Economic Impact	Fisheries
Fishermen are required to kill Northern Snakeheads when caught (Pennsylvania Fish and Boat Commission 2023, https://www.media.pa.gov/pages/fish-and-boat-commission-details.aspx?newsid=534)

References

Orth, Donald J. (2010) Socrates Opens a Pandora’s Box of Northern Snakehead Issues, American Fisheries Society Symposiums 89: 203-221

Courtenay, Walter R., Jr.; Williams, James D. (2004) Snakeheads (Pisces, Channidae)- A biological synopsis and risk assessment., United States Geological Survey Circular 1251: 1-151

Dennen, Rusty 5/15/2013 Snakeheads slithering up Rappahannock. <missing URL>



Dolin, Eric J. (2003) Snakehead, Smithsonian Institution, Washington, DC. Pp. <missing location>

du Lac, J. Freedom (5/22/2012) Angler may have broken world record with snakehead caught in Occoquan River, Washington Post <missing volume>: published online

Fahrenthold, David A; Partlow, Joshua (Oct. 5, 2004) Baby snakehead is no bundle of joy., Washington Post <missing volume>: B-1

Fahrenthold, David A. (May 29, 2005) In river of many aliens, snakehead looms as threat., Washington Post newspaper <missing volume>: 1-3

Fahrenthold, David, A. 10/2/2006 Snakeheads appear at home in the potomac. <missing URL>



Farenthold, David May 4, 2004 Confidence grows that Wheaton Lake is "Snakehead-free".. <missing URL>



Fears, Darryl (1-29-2013) At benefit, eating snakehead to help the Chesapeake Bay, Washington Post published online: <missing location>

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