Preventative measures: The northern snakehead has a wider latitudinal range and temperature tolerance than other snakehead species, which indicates that it could become established throughout most of the contiguous United States and some waters in adjoining Canadian provinces (Courtenay and Williams, 2004). In a Canadian risk assessment prepared by Cudmore & Mandrak (2006) Part I (Aquatic Organism Ecological and Genetic Risk Assessment Process) revealed a "High probability of establishment estimate" (reasonably certain) and a "High consequences of establishment estimate" (reasonably certain), giving a "Final Risk Estimate" of "High" (reasonably certain). Similarly, Part II (Pathogen, Parasite or Fellow Traveler Risk Assessment Process) revealed a "Medium probability of establishment estimate" (reasonably certain) and a "Medium consequences of establishment estimate" was "Medium" (very uncertain), giving a "Final Risk Estimate" of "Medium" (very uncertain).
All snakeheads were banned from importation and interstate transport in the USA in October 2002 by the US Fish and Wildlife Service under the Lacy Act (NSWG 2006). In the USA anglers and commercial fisherman have been asked to kill and freeze all snakeheads rather than re-release them and immediately report them to the local Fish and Game Department (Sea Grant 2007).
Chemical: In Crofton pond, Maryland (USA) herbicides (Diquat Dibromide and Glyphosate) were used to lower oxygen levels, then a piscicide (Rotenone) was used to poison the fish (Hilton 2002). The total cost of this eradication in a 1.8 ha pond was estimated at $110,000 (Courtenay & Williams 2004). Eradication would be much more complicated in rivers, streams, or larger lakes.
Physical: Electrofishing and netting may provide a low level of control to established populations but would not result in eradication due to selectivity of certain size classes (NatMangPln).
Decision support tools for identifying potentially invasive non-native marine and freshwater species (fish, invertebrates and amphibians) have been adapted from Pheloung Williams and Halloy (1999) Weed Risk Assessment. Please follow this link to access the decision support tool and kit.
A Risk-assessment for non-native freshwater species in the UK is available for determining the level of potential invasion The assessment can aid resource managers in decision making when it comes to management strategies.
Location Specific Management Information
An attempt was made to eradicate Channa argus in Arkansas in 2007 by U.S. Fish and Wildlife Service. However the attempt failed at a cost of over US $750,000 (W. Courtenary, pers. comm. 2010).
Following confirmation of the presence of Channa argus in a 1.8 ha retention pond in Crofton, Maryland, and proof that the species was established as a reproducing population, the pond and two adjacent smaller ponds were treated with herbicides (Hilton, 2002 names them as Diquat Dibromide and Glyphosate) to lower oxygen levels on 18 August 2002. On the 4th September 2002, a piscicide (Rotenone) was used to successfully exterminate the population (W. Courtenay, pers. comm. 2010)A July 2002 report which details planning for the eradication plans of the snakehead population at Crofton is available at http://www.dnr.state.md.us/irc/ssap_report.html
Preventative measures: The confirmation of northern snakeheads in this pond resulted in significant media attention in Maryland and generated numerous resources for risk identification and the development of action plans to prevent the introduction of this nonnative species into state waters (Lazur Early & Jacobs 2006).
Chemical control: Rotenone was selected as an eradication option, and a bioassay was conducted with captured northern snakehead juveniles to determine toxicity and application dose (Lazur Early & Jacobs 2006). The lowest rotenone concentration evaluated, 0.075 mg of active ingredient per liter of water, resulted in 100% mortality within one hour; pond treatment was highly successful; 8 adult and 834 juvenile snakeheads were recovered (Lazur Early & Jacobs 2006). Study results show that northern snakeheads are susceptible to normal doses of rotenone and that standard pond treatment techniques are effective in eradicating this invasive species (Lazur Early & Jacobs 2006). The cost of the of this eradication was estimated at USD 110 000 (Courtenay & Williams 2004).
In 2008 the New York State Department of Environmental Conservation treated Ridgebury Lake and Catlin Creek with the aquatic pesticide CFT Legumine (Rotenone) at 4 PPM in order to eradicate Channa argus. Temporary fish barriers were constructed along the creek to slow movement and partially block passage downstream. Over 220 specimens were found throughout the treatment area, most of which were juveniles (NYDEC 2008). To date there is no confirmation of eradication (W. Courtenary, pers. comm. 2010).
Local state biologists have decided not to attempt eradication, which would be unlikely considering its spread, but have instead decided to continue monitoring it (Sea Grant Pennsylvania 2007).
Anglers, commercial fishermen, and fisheries professionals should know how to identify the northern snakehead. If you think you’ve caught a snakehead DO NOT put it back into the water. Instead, kill it, freeze it, and notify the Pennsylvania Fish and Boat Commission. Make note of where you capture it, because the information is useful for determining distribution and possible control methods (Sea Grant Pennsylvania 2007).
Legislation: It is unlawful in Pennsylvania to possess, sell, or purchase live snakeheads. It is also unlawful to introduce, import or stock live snakehead
species into Pennsylvania waters (Sea Grant Pennsylvania 2007).
Potomac River Basin (Potomac River)
The northern snakehead has established a reproducing and expanding population in the Potomac River system where Virginia and Maryland are trying to eradicate or at least control it. The Virginia Department of Game and Inland Fisheries conducts periodic electro-fishing surveys in the areas (VDGIF 2009). The use of passive gears during the spring dispersal period may be an effective means of control, however this has not yet been tested (N. Lapointe Pers. Comm. 2009).
United States (USA)
Channa argus is on the list of Federal Prohibited Fish, Mollusks, and Crustaceans, including the live fish or viable eggs of snakehead fishes of the genera Channa and Parachanna of the Family Channidae (South Carolina Department of Natural Resources 2007).
1. Centre for Environment, Fisheries & Aquaculture Science (CEFAS)., 2008. Decision support tools-Identifying potentially invasive non-native marine and freshwater species: fish, invertebrates, amphibians.
Summary: The electronic tool kits made available on the Cefas page for free download are Crown Copyright (2007-2008). As such, these are freeware and may be freely distributed provided this notice is retained. No warranty, expressed or implied, is made and users should satisfy themselves as to the applicability of the results in any given circumstance. Toolkits available include 1) FISK- Freshwater Fish Invasiveness Scoring Kit (English and Spanish language version); 2) MFISK- Marine Fish Invasiveness Scoring Kit; 3) MI-ISK- Marine invertebrate Invasiveness Scoring Kit; 4) FI-ISK- Freshwater Invertebrate Invasiveness Scoring Kit and AmphISK- Amphibian Invasiveness Scoring Kit. These tool kits were developed by Cefas, with new VisualBasic and computational programming by Lorenzo Vilizzi, David Cooper, Andy South and Gordon H. Copp, based on VisualBasic code in the original Weed Risk Assessment (WRA) tool kit of P.C. Pheloung, P.A. Williams & S.R. Halloy (1999).
The decision support tools are available from: http://cefas.defra.gov.uk/our-science/ecosystems-and-biodiversity/non-native-species/decision-support-tools.aspx [Accessed 13 October 2011]
The guidance document is available from http://www.cefas.co.uk/media/118009/fisk_guide_v2.pdf [Accessed 13 January 2009].
4. Courtenay, W., pers. comm. May 2003.
Summary: Additional information provided via email correspondece during review of species profile.
8. Lazur, A., Early, S. & Jacobs, J.M. 2006. Acute toxicity of 5% rotenone to northern snakeheads. North American Journal of Fisheries Management. 26(3). 628-630.
Summary: Abstract: The confirmation of northern snakeheads Channa argus caught by an angler in a private pond in Maryland resulted in significant media attention and generated numerous resources for risk identification and the development of action plans to prevent the introduction of this normative species into state waters. Rotenone was selected as an eradication option, and a bioassay was conducted with captured northern snakehead juveniles to determine toxicity and application dose. The lowest rotenone concentration evaluated, 0.075 mg of active ingredient per liter of water, resulted in 100% mortality within 1 h. Pond treatment was highly successful; 8 adult and 834 juvenile snakeheads were recovered. Study results show that northern snakeheads are susceptible to normal doses of rotenone and that standard pond treatment techniques are effective in eradicating this invasive species./p
10. Mendoza, R.E.; Cudmore, B.; Orr, R.; Balderas, S.C.; Courtenay, W.R.; Osorio, P.K.; Mandrak, N.; Torres, P.A.; Damian, M.A.; Gallardo, C.E.; Sanguines, A.G.; Greene, G.; Lee, D.; Orbe-Mendoza, A.; Martinez, C.R.; and Arana, O.S. 2009. Trinational Risk Assessment Guidelines for Aquatic Alien Invasive Species. Commission for Environmental Cooperation. 393, rue St-Jacques Ouest, Bureau 200, Montréal (Québec), Canada. ISBN 978-2-923358-48-1.
Summary: In 1993, Canada, Mexico and the United States signed the North American Agreement on Environmental Cooperation (NAAEC) as a side agreement to the North American Free Trade Agreement (NAFTA). The NAAEC established the Commission for Environmental Cooperation (CEC) to help the Parties ensure that improved economic efficiency occurred simultaneously with
trinational environmental cooperation. The NAAEC highlighted biodiversity as a key area for trinational cooperation. In 2001,
the CEC adopted a resolution (Council Resolution 01-03), which created the Biodiversity Conservation Working Group (BCWG),
a working group of high-level policy makers from Canada, Mexico and the United States. In 2003, the BCWG produced
the “Strategic Plan for North American Cooperation in the Conservation of Biodiversity.” This strategy identified responding to
threats, such as invasive species, as a priority action area. In 2004, the BCWG, recognizing the importance of prevention in addressing
invasive species, agreed to work together to develop the draft CEC Risk Assessment Guidelines for Aquatic Alien Invasive
Species (hereafter referred to as the Guidelines). These Guidelines will serve as a tool to North American resource managers
who are evaluating whether or not to introduce a non-native species into a new ecosystem. Through this collaborative
process, the BCWG has begun to implement its strategy as well as address an important trade and environment issue. With increased
trade comes an increase in the potential for economic growth as well as biological invasion, by working to minimize the potential adverse
impacts from trade, the CEC Parties are working to maximize the gains from trade while minimizing the environmental costs.
Available from: English version: http://www.cec.org/Storage/62/5516_07-64-CEC%20invasives%20risk%20guidelines-full-report_en.pdf [Accessed 15 June 2010]
French version: http://www.cec.org/Storage/62/5517_07-64-CEC%20invasives%20risk%20guidelines-full-report_fr.pdf [Accessed 15 June 2010]
Spanish version: http://www.cec.org/Storage/62/5518_07-64-CEC%20invasives%20risk%20guidelines-full-report_es.pdf [Accessed 15 June 2010].
14. Rixon C.A.M., I.C. Duggan, N.M.N. Bergeron, A. Ricciardi & H.J. Macisaac. 2005. Invasion risks posed by the aquarium trade and live fish markets on the Laurentian Great Lakes. Biodiversity and Conservation Volume 14, Number 6
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