How Many Species of Snakehead Fishes are in the USA? by Don Orth

The summer of 2002 was the summer of the snakehead — the first exposure with these exotic fishes for many of us.  It began with the first appearance of the Northern Snakehead Channa argus in a small pond in Crofton, Maryland.   Snakehead fishes are air-breathing freshwater fishes in the family Channidae. The genus Channa includes snakeheads of Asia, Malaysia, and Indonesia, and the genus Parachanna occur in Africa. In their native range, they are important food fish. Elsewhere, snakeheads are popular in live food fish and aquarium trades and many species are cultured for food.  Recently sport fishing for snakeheads has grown in popularity. After the establishment of the Northern Snakehead in the Potomac River, it spread to other tributaries of Chesapeake Bay and scientists are concerned about its potential to spread into all the Great Lakes except Superior (Kramer et al. 2017; Love and Newhard 2018).  In all habitats it colonizes, scientists will need to evaluate its potential to threaten native fishes, the recreational fishing industry, and aquatic ecosystems, all of which will cost time and money.

Top Ten Little Known Facts about the Snakehead Fish. 

(The Late Show with David Letterman, Dolin 2003).

10.       The fish is 50 percent snake, 50 percent head. 

9.         Mortal enemy is the fishhead snake.

8.         High-protein diet of fish and frogs means slim look for summer. 

7.         They love kids.

6.         Bush promised to find and catch them…of course we’ve heard that before. 

5.         Fans of the snakehead fish are known as snakehead-heads.

4.         Available for a limited time at participating Red Lobsters. 

3.         It’s very popular with lawyers, am I right people?

2.         Developed by the government to distract people from the whole Cheney-Halliburton thing. 

1.         It’s the result of a drunken genetic engineer and a dare. 

Many initial fears were overblown or laughed off by comedians who managed to pass on misinformation about the snakehead.   This infographic in The Onion from 2002 joked about the  snakehead signing movie deals left and right.  Snakehead fish played a feature role in four movies, including Snakehead Swamp, Frankenfish, Snakehead Terror, and Swarm of the Snakehead. But the movie hype only distracted us from learning more about the potential for the snakehead to cause harm. 

Invasive species are serious concerns as our global society facilitates transcontinental introductions.  An invasive species is "an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health" as per Executive Order 13112: Section1. Definitions. Defining harm is the most difficult prerequisite to devising management interventions. Charles Elton introduced the militaristic "invasion" metaphor to describe exotic plants and animals in the 1950s and we’re often stuck with a Mission Impossible situation. Julian Olden, Professor in the School of Aquatic and Fishery Sciences at the University of Washington, refers to this approach as the "guilty even when proven innocent."  

The snakehead family of fishes have been federally regulated since 2002 when they were listed as injurious wildlife under the Federal Lacey Act (18 USC 42), which makes it illegal to import injurious wildlife into the United States or transport between the listed jurisdictions in the shipment clause (the continental United States, the District of Columbia, Hawaii, the Commonwealth of Puerto Rico, and any possession of the United States) without a permit. An injurious wildlife listing would not prohibit intrastate transport or possession of that species within a State where those activities are not prohibited by the State. See also: Injurious Wildlife: A Summary of the Injurious Provisions of the Lacey Act. 

The first step in determining harm is to map out the occurrence and consider where and what other species it might influence.  But this is not a simple step because there are five, not one, species of snakehead fish known to occur in USA (Benson 2019).

Blotched Snakehead Channa maculata is native to southern China and Vietnam.  It was the first snakehead introduced to the island of O’ahu, Hawaii in the late 1800s.  It became established there in ditches, ponds, and reservoirs.  

from USGS

Giant Snakehead Channa micropeltes is tropical-subtropical species native to India, southeast Asia, including the peninsular Malaysia.  It has been collected in six states presumably due to aquarium releases (Benson 2019). 

Giant Snakehead Source

Giant Snakehead juvenile. Source

Northern Snakehead Channa argus is a temperate species native to the Korean peninsula and eastern rivers of China and Russia.  Northern Snakehead have been collected from 13 states and the District of Columbia (Benson 2019).   Northern Snakehead has established populations from Arkansas, Virginia, Maryland, Delaware, New Jersey, and New York. History of introductions of the Northern Snakehead is chronicled in Benson (2019).  Populations originated from escapees from fish culture ponds (banned in 2002), live food markets, and human assisted introductions.

Northern Snakehead.  Illustration by Susan Trammell. Source

Chevron Snakehead Channa striata is a a warm temperate species native to Pakistan and parts of southeast Asia.  It was introduced into Hawaii as broodstock for commercial aquaculture. 

Chevron Snakehead.  USGS

Bullseye Snakehead Channa marulius is native to tropical and warm temperate regions of southeast Asia, southern China, and Pakistan.  The Bullseye Snakehead has been established in southern Florida since at least 2000, but has not colonized Everglades National Park or Big Cypress Natural Preserve.  

Bullseye Snakehead.  (c) Michigan Science Art.  Source.

It helps that we know more about the distribution of these five snakehead fishes.  Context is everything.   Before snakehead fish were banned for import, live snakeheads were common in live-food markets where they could easily be released to create fisheries or for prayer release ceremonies. The Buddhist practice known as ‘live release’, ‘fang sheng’, ‘mercy release’, and ‘prayer animal release’, entails the release into the wild of captive animals and particularly those destined for slaughter. However, this ancient practice would release animals to their native habitats (Everard et al. 2019).   

Given the multiple species and settings for introduction, we need to treat each case and context according to best information regarding harm and feasible management policies (SPDC 2014; Orth 2019).  To develop and enact sensible policies, it is crucial to consider two philosophical questions: (1) What exactly makes a species native or exotic, and (2) What values are at stake? (Woods and Moriarty 2001). Humans are important vectors so the solution to widespread dispersal must focus on human behavior. Importing live snakeheads is prohibited as is their interstate transport.  Maryland and Virginia prohibit possession of live snakeheads.  Penalties for transporting live Snakehead should be continued and communicated widely.  Fishing and bow fishing have potential to reduce local abundance of Northern Snakehead in Potomac tributaries.   Whether we can eat our way out of the snakehead abundance is yet to be seen, though plenty of recipes will work for this tasty fish.    

Snakehead Cakes prepared by Alewife Restaurant, Baltimore.  Photo by D.J. Orth.

References

Benson, A.J. 2019. Snakehead fishes (Channa spp.) in the USA.  Pages 000-000 in D. Chapman and J. Odenkirk, editors.  First International Snakehead Symposium, American Fisheries Society Symposium 89.  Bethesda, Maryland.  

Dolin, E.J. 2003.  Snakehead: Fish out of water.  Smithsonian Books, Washington, D.C.

Everard, M., A.C. Pinder, R. Raghavan, and G. Kataria. 2019.  Are well-intended Buddhist practices an under-appreciated threat to global aquatic biodiversity?  Aquatic Conservation Marine and Freshwater Ecosystems 29:136-141. 

Kramer, A. M., G. Annis, M. E. Wittmann, W. L. Chadderton, E. S. Rutherford, D. M. Lodge, L. Mason, D. Beletsky, C. Riseng, and J. M. Drake. 2017. Suitability of Laurentian Great Lakes for invasive species based on global species distribution models and local habitat. Ecosphere 8(7):e01883.

Love, J.W., and J.J. Newhard. 2018. Expansion of Northern Snakehead in the Chesapeake Bay watershed. Transactions of the American Fisheries Society 147:342-349.

Orth, D.J. 2019.  Socrates opens a Pandora’s Box of Northern Snakehead issues.   Pages 000-000 in D. Chapman and J. Odenkirk, editors. First International Snakehead Symposium, American Fisheries Society Symposium 89.  Bethesda, Maryland.  

Snakehead Plan Development Committee (SPDC). 2014. Draft National Control and Management Plan for Members of the Snakehead Family (Channidae).Submitted to the Aquatic Nuisance Species Task Force.  https://www.anstaskforce.gov/Species%20plans/SnakeheadPlanFinal_5-22-14.pdf Accessed July 5, 2018.

Woods, M., and P. Moriarty. 2001. Strangers in a strange land: The problem of exotic species. Environmental Values10:163-191.

Northern Snakehead Expanding Range, by Don Orth

On May 14, 2002, a Maryland angler caught (and released) a 17 inch snakehead fish in a stormwater detention pond in Crofton, Maryland.  Six weeks later another angler caught a 26 inch snakehead.  Juveniles were dipnetted a week later, confirming a reproducing population.  The snakehead population was eradicated but Northern Snakehead Channa argus were already in the Potomac River and tributaries (Odenkirk and Owens 20007).  Yet, this fish is native to China and North Korea and in 2005 Congress directed the U.S. Fish and Wildlife Service "to identify, contain, and eradicate the species.”  The family of snakehead fishes (Channidae) includes 26 airbreathing fishes native to Asia, Malaysia, Indonesia, and tropical Africa.  Several species have been introduced to the US  for sale in ethnic markets and restaurants that hold live fish for customer selection.  Ten species of snakehead (Channa spp) were deemed high risk for establishment (Herborg et al. 2007).  Uncertainty about this exotic fish resulted in exaggerated fear-based reactions.  Snakehead Terror and Swarm of the Snakehead  are full-length horror films based on the exotic snakehead.   Should you be terrorized?

Illustration of Northern Snakehead Channa argus.   Berg 1933. (Courtney and Williams 2004).

What do we know about Northern Snakehead?   Northern Snakehead are readily identified by the long dorsal and anal fins, pelvic fins located beneath the pectoral fins, a truncate caudal fin, and a large mouth that extends far beyond the eye.  The mouth attracts most attention with its large canine-like teeth on upper and lower jaws.   The coloration is golden tan to pale brown or olive with a series of dark irregular patches on sides and saddle-like blotches across the back.   The largest specimens from Virginia waters were 34 inches (Odenkirk et al. 2013), but larger ones are reported by bowfishers and anglers.  The Maryland state record is 18.42 pounds.  Northern Snakehead are effective ambush predators as adults and diet is mostly banded killifish Fundulus diaphanous, white perch Morone americana, bluegill Lepomis macrochirus, and pumpkinseed sunfish Lepomis gibbosus, all common fishes(Odenkirk and Owens 2007).   Northern Snakeheads are commonly caught by bass anglers and bowfishers target them.
 

Northern Snakehead Channa argus   Photo by D.J. Orth.

How far might they spread?  Since the nonindigenous Northern Snakehead became established in the Potomac drainage, the fear factor has diminished and investigators have discovered some critical information about this fish in its new habitat.  The potential for widespread dispersal through North America is very great considering its broad environmental requirements and adaptations (Herborg et al. 2007), as well as the multiple reservoirs in the Northern Virginia region.  Northern Snakehead has spread through the Potomac (Fuller et al. 2015) and now extends throughout the lower Potomac from Great Falls to the mouth, including some tidal portions with moderate salinity (up to 7.6 ppt; Starnes et al. 2011).  Also, it has recently spread to the Rappahannock drainage (Strong 2013).  These conditions make the Potomac region relevant to continent-wide spread as well as a model system for evaluating naturalization and understanding migration and movement patterns in the Northern Snakehead.  
 

Distribution of known Northern Snakehead Channa argus populations in the United States (Fuller et al. 2015.

Suitability of the environment for the Northern Snakehead (Herborg et al. 2007).

Are they expanding their range?   Yes, Northern Snakehead is more widespread than other invasive fishes including the Blue Catfish Ictalurus furcatus and Flathead Catfish Pylodictus olivaris  (Love and Newhard 2018).  They are now found in "nearly every major drainage of Maryland's tidal portion of the Chesapeake Bay watershed" (Love and Newhard 2018).  Snakehead have colonized new watersheds via migrations through waters with salinities exceeding 6-12 ppt.  Movements increased in response to water temperatures warming above 14°C (Lapointe et al. 2013).  Gascho Landis et al. (2011) characterize the pre-spawn season (April-June) as a time of high feeding and gonad growth.  Spawning begins when water temperatures reach 26°C and may spawn multiple times occur over a long period;  nest guarding occurs from July to mid-September.   The population likely expands periodically during times when freshwater inflows permits the Northern Snakehead to move with freshwaters.  Northern Snakehead is also established in the Mississippi River basin in Arkansas. 

Northern Snakehead populations (ovals) occur as metapopulations that are connected via migration (arrows) and human-assisted transport.

Genetic analysis supports the hypothesis that five genetically distinct populations of Northern Snakehead occur in the US (Resh et al. 2018.  The Arkansas population is most genetically differentiated from the Potomac River population and effectively population sizes are high.  

Snakeheads are a favored food fish in India and parts of Asia.  Here and elsewhere they are specialty foods available live for selection at upscale restaurants.   Management of the Northern Snakehead and other snakehead species is complicated by trade in the live food fish market.  China has been the largest exporter of snakehead (Snakehead Plan Development Committee 2014).  As if the US-China trade policy needed any more sources of conflict, the snakehead is likely far down the list of trade issues.  Many states and provinces have enacted bans on possession, transport, and breeding of snakehead fish.  Since snakehead are "injurious" wildlife under the Lacey Act, the U.S. Fish and Wildlife Service Office of Law Enforcement seizes illegal shipments.   Eradication of Northern Snakehead in open systems, such as the Chesapeake Bay, is unlikely given the large effective population size (Resh et al. 2018).  But don't feel terrorized.  An effective snakehead solution will rely on dealing with the unauthorized release into public waters. Humans are the vector.  Humans are the solution.

References

Courtney, W.R., Jr., and J.D. Williams. 2004.  Snakeheads (Pisces, Channidae) -- A biological synopsis and risk assessment.   U.S.G.S. Circular 1251. 143 pp. 

Fuller, P.F., A. J. Benson, G. Nunez, A. Fusaro, and M. Neilson. 2015. Channa argus. USGS nonindigenous aquatic species database, Gainesville, FL. Available online at http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=2265   Accessed December 4 2015.

Gascho Landis, A. M., N. W. R. Lapointe, and P. L. Angermeier. 2011. Individual growth and reproductive behavior in a newly established population of northern snakehead, Potomac River, USA. Hydrobiologia 661:123-131.

Herborg, L-M., N.E. Mandrak, B.C. Cudmore, and H.J. MacIsaac.  2007.  Comparative distribution and invasion risk of snakehead (Channidae) and Asian carp (Cyprinidae) species in North America.  Canadian Journal of Fisheries and Aquatic Sciences 64:1723-1735.

Lapointe, N.W.R., J.S. Odenkirk, and P.L. Angermeier. 2013.  Seasonal movement, dispersal, and home range of Northern Snakehead Channa argus (Actinopterygii, Perciformes) in the Potomac River catchment. Hydrobiologia 709:73-87.

Love, J.W., and J.J. Newhard. 2018.  Expansion of Northern Snakehead in the Chesapeake Bay watershed.  Transactions of the American Fisheries Society   DOI: 10.1002/tafs.10033

Odenkirk, J. and S. Owens. 2007.  Expansion of the Northern Snakehead population in the Potomac River system. Transactions of the American Fisheries Society 136:1633-1639.

Odenkirk, J., C. Lim, S. Owens, and M. Isel. 2014. Insight into age and growth of northern snakehead in the Potomac River. North American Journal of Fisheries Management 33:773-776.

Orrell, T. M., and L. Weigt. 2005. The northern snakehead Channa argus (Anabantomorpha: Channidae), a nonindigenous fish species in the Potomac River, USA.  Proceedings of the Biological Society of Washington 118:407–415.

Owens, S.J., J.S. Odenkirk, and R. Greenlee. 2008. Northern snakehead movement and distribution in the tidal Potomac River system. Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies 62:161–167.

Resh, C.A., M.P. Galaska, and A.R. Mahon. 2018.  Genomic analyses of Northern snakehead (Channa argus) populations in North America.  Peer J 6:e4581; DOI 10.7717/peerj.4581

Saylor, R., N. Lapointe, and P. Angermeier. 2012. Diet of non-native Northern Snakehead (Channa argus) compared to three co-occurring predators in the lower Potomac River, USA. Ecology of Freshwater Fish 21:443-452.

Snakehead Plan Development Committee. 2014. Draft  National Control and Management Plan for Members of the Snakehead Family (Channidae) Department of Interior.  73 pp.  Available at http://www.anstaskforce.gov/Species%20plans/SnakeheadPlanFinal_5-22-14.pdf

Starnes, W.C., 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.

Strong, T.  2013.  Snakeheads break out of the Potomac, enter Rappahannock river.  Richmond Times-Dispatch May 17, 2013.  Available at http://www.richmond.com/news/science/article_3c16a8c7-8ecd-5ea8-a095-2878ddcf7d3d.html   Accessed December 4, 2015