Submitted by: Karley Wright and Nick Colacci
The Northern Snakehead, Channa argus, is one of the most globally distributed of any Snakehead species (Qin, 2017). Originating in areas of eastern China, Korea, and southern Siberia, the Northern Snakehead has expanded its range throughout Europe and Asia, as well as making its way into Nigeria and several states in the U.S.A. (Poulos, Chernoff, Fuller, & Butman, 2012; Qin, 2017). Although the Northern Snakehead is considered to have the potential to establish in Ontario, there is currently no record of this fish in any Ontario waters (Herborg, Mandrak, Cudmore, & MacIsaac, 2007). Figure 1 highlights the general global distribution of the Northern Snakehead.
Figure 1: General global distribution of the Northern Snakehead, Channa argus. The hardiness and ability of the species to tolerate a wide range of temperature has allowed it to become established in several areas outside of its native range (Base map: ESRI 2018; Distribution modified from Qin, 2017 and U.S. Fish and Wildlife Service, 2017)
The Northern Snakehead requires a temperate and freshwater system, ideally at shallow depths of 0.5-3 meters and at a temperature range of 0-30 degrees Celsius in slow-moving or stagnant waters (Whedbee, 2017). These conditions are abundant especially in the United States in canals, reservoirs, lakes, ponds, slow-moving rivers or streams, temporary pools, and brackish waters as well as wetlands such as marshes and swamps (Walter R. Courtenay & Williams, 2004). Broadening their potential habitat, the Northern Snakehead is also capable of brief travel on land in riparian and estuarine zones as it is an air-breathing fish with large muscle mass used to propel itself from waterbody to waterbody. As the Northern Snakehead is a voracious and omnivorous feeder, habitat is mainly selected based on physical conditions, not prey availability. During spawning, the Northern Snakehead looks for areas of low turbidity where the male will build nests out of aquatic plants and any vegetation above is cleaned away by both parents. Nest sites can reach 1m in diameter and are located in shallow areas (Qin, 2017). Juveniles have a diet consisting of small crustaceans as well as other fish larvae. Mature Snakeheads feed on a range of fish up to 33% of their own body size but are adaptable to feeding on other organisms such as frogs, crustaceans, and insects (Whedbee, 2017).
Although the northern snakehead exhibits traits of both K and r strategists, it is more in line with the classification of r- strategist. The Northern Snakehead generally reaches maturity around 2 to 3 years of age. Due to large numbers of eggs laid multiple times per year and parental care, population growth is generally rapid.
Table 1: A summary of Northern Snakehead reproductive strategies. This species best suits the classification of r- strategist. Chart adapted from (Feltham, 2017). Information adapted from (Courtenay & Williams, 2004; Qin, 2017).
|Mortality||Varied and unpredictable||More constant and predictable||Mortality is much higher in juvenile fish|
|Lifespan||Short||Long||Up to 8 years|
|Number of Eggs||Large||Small||Large – varied depending on strain ranging from 1300-15,000 eggs, with the Amur strain capable of 21,000 to 51,000 and Syr Dar’ya strains producing 28,600 to 115,000|
|Parental Investment/Care||Very little, if any||Required||Both parents care for eggs and fry until juveniles are 4-5 cm (roughly 4 weeks old)|
|Frequency of Reproduction||Once to multiple times over a short time period||Multiple times, over a prolonged period||One to five times per year for multiple years|
|Additional Factors||Most reproductively mature individuals reproduce successfully||Few reproductively
only some reproduce
|Most reproductively mature individuals reproduce successfully, with different partners|
Northern Snakehead have a much higher chance of survival at a mature age, putting them into the classification of a type III survivorship curve (see figure 3). The hardy, aggressive nature of these fish make survival rates much greater once they reach a size that is not easily preyed upon by other fish. Northern Snakehead are most vulnerable aa juveniles when many fish and invertebrates feed upon them; however, the parental care they receive helps to reduce this.
Figure 3: The Northern Snakehead has a type 3 survivorship curve, because survival of eggs and juvenile fish is much less likely than in adults. Predation on eggs and juveniles is a key factor limiting the survivorship of young fish (Feltham, 2015).
Dispersal and Vectors
Northern snakehead can travel through a wide range of fresh water, with a wide temperature tolerance and ability to breathe air in low oxygen situations, salinity is the limiting factor to travel. It should also be noted that this species will generally avoid fast moving water (Herborg et al., 2007). The northern snakehead is commonly cultured as a food source in China and Korea. Live exportation of this species has occurred to Canada and the United States, with the intention of being sold in live fish markets and restaurants (Poulos et al., 2012). Prior to the ban of live Northern snakehead in America, there is also record of the species being kept in aquaculture ponds in the United States (Courtenay & Williams, 2004). Secondary release from live fish markets and escape from aquaculture ponds are major vectors for dispersal of this species. Northern snakehead do not require large floods to escape from ponds, as they are capable of travel over land. They are unable to walk and this process is more of a slow clumsy squirm, the fish is not likely to move unless the waterbody they inhabit is drying up, or there is a lack of food (Qin, 2017). The body shape of adults does not allow them the same mobility as juveniles. However, both life stages can survive up to 4 days on land, provided they remain wet. These fish only resort to travelling on land when conditions are poor, such as a lack of food (Courtenay & Williams, 2004; U.S. Fish and Wildlife Service, 2017; Qin, 2017). Northern Snakehead have been released from aquariums when owners did not want to provide care for them, and have also been introduced to Japan to provide a new option for sport fishing (U.S. Fish and Wildlife Service, 2017).
Adult Northern Snakehead feed heavily on fish and have been known to take on prey up to one third of their size, while juveniles feed heavily on fish larvae, zooplankton, and small crustaceans. This fish has a very aggressive nature and large appetite (Courtenay & Williams, 2004; Government of Saskatchewan , 2016). Adults are capable of reaching 1 meter in length and face little in the way of natural predation (Government of Saskatchewan, 2016).
Courtenay, W. R., & Williams, J. D. (2004). SNAKEHEADS (Pisces, Channidae) A Biological Synopsis and Risk Assessment. Retrieved from USGS: https://archive.usgs.gov/archive/sites/fl.biology.usgs.gov/Snakehead_circ_1251/circ_1251_courtenay.pdf
Feltham, J. (2015). Curbing Population Growth: Effective Population Management. Retrieved from Human and Wildlife Ecology: https://humanwildlifeecology.wordpress.com/home/curbing-population-growth-effective-population-management/
Fuller, P., Benson, A., Nunez, G., Fusaro, A., & Neilson, M. (2017). Channa argus. Retrieved from NAS – Nonindigenous Aquatic Species: https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=2265
Government of Canada. (2018, January 16). Northern Snakehead. Retrieved from Fisheries and Oceans Canada: http://www.dfo-mpo.gc.ca/science/environmental-environnement/ais-eae/species/northern-snakehead-eng.html
Government of Saskatchewan . (2016). Stop Aquatic Invasive Species. Retrieved from Saskatchewan: http://www.environment.gov.sk.ca/adx/aspx/adxGetMedia.aspx?DocID=7bd9d237-1b03-4d6d-b146-0c57d76790d6
Herborg, L.-M., Mandrak, N. E., Cudmore, B. C., & MacIsaac, H. J. (2007). Competitive distribution and invasion risk of snakehead (Channidae) and Asian carp (Cyprinidae) species in North America. Retrieved from Fisheries and Oceans Canada: http://www.dfo-mpo.gc.ca/science/documents/coe-cde/ceara/Herborg_etal_Asiancarps_CJFAS.pdf
NAS. (2018, February 2). NAS- Nonindigenous Aquatic Species. Retrieved from USGS: https://nas.er.usgs.gov/viewer/omap.aspx?SpeciesID=2265
Poulos, H. M., Chernoff, B., Fuller, P. L., & Butman, D. ((2012)). Ensemble forecasting of potential habitat for three invasive fishes. Aquatic Invasions Volume 7, Issue 1: 59–72, 59-72. Retrieved from http://eds.b.ebscohost.com.eztest.ocls.ca/eds/pdfviewer/pdfviewer?vid=3&sid=1a5cfc62-7157-45c2-8d74-d357d0702d00%40sessionmgr103
Qin, J. (2017). Channa argus argus (northern snakehead). Retrieved from CABI: https://www.cabi.org/isc/datasheet/89026
U.S. Department of the Interior U.S. Geological Survey. (n.d.). Snakeheads (Pisces, Channidae)- A biol. Retrieved from USGS: https://pubs.usgs.gov/circ/2004/1251/report.pdf
Walter R. Courtenay, J., & Williams, J. D. (2004). Snakehead (Pisces, Channidae)- A Biological Synopsis And Risk Assessment. Retrieved from USGS: https://pubs.usgs.gov/circ/2004/1251/report.pdf
Whedbee, J. (2017). Channa argus. Retrieved from Animal Diversity Web: http://animaldiversity.org/accounts/Channa_argus/#geographic_range