The Northern Snakehead: A Credible Threat

 

by Noelle Hatton, Thousand Island Boat Steward

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The invasive northern snakehead (Channa argus) is of the family Channidae.  Also known as the amur snakehead, eastern snakehead, and the oscillated snakehead, it is a native of China, Russia and Korea.  More specifically, it is found in the Amur River basin (hence the nickname).  The fish are long and thin, with a relatively flat head.  The dorsal fin is long and runs along the length of the fish, from the base of the pectoral fins to the caudal fin.  The anal fin is also elongated and is more than half the length of the dorsal fin.  They are obligate air breathers, which make them very capable of living in oxygen-depleted environments.  Snakeheads prefer to live in shallow, muddy streams or swamps, but they utilize deeper waters in winter months, which makes them perfect candidates for the Great Lakes.  They are highly adaptable and at low temperatures, their metabolism rate and oxygen demand decrease which allow them to survive the ice cover during winter months.

Usually, snakeheads reproduce after 2-3 years of age, but are capable of making young after only a year of growth.  The fish can spawn up to five times during the year (usually from April to August) and each time can produce 1300-1500 eggs.  They can hatch within three days and grow at a rapid rate.  Initially, the fry eat zooplankton and work their way up to small insects, crustaceans, small fish, beetles and frogs.  As adults, snakeheads have a large diet and can consume fish up to 33 percent of its body length.  The fish can survive out of water for four days, and as juveniles, they can migrate overland because of their horizontally flat body.

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Snakeheads’ mouth are filled with many sharp teeth. Photo: U.S. Geological Survey Archive, U.S. Geological Survey, bugwood.org

This invasive species was established in the United States via live fish markets and aquarium dumping.  They have been found in many states, but only have documented populations in the states of Arkansas, Maryland, Virginia, Pennsylvania and southern parts of New York.  In smaller lakes and streams where specimens have been found, eradication attempts were made with the pesticide/piscicide rotenone.  Snakehead are currently on the watch list for the Great Lakes to avoid establishment, as they could survive and out-compete native fish species for food and habitat.  Under the Lacey Act, the importation and cross-border transplant of the species was banned in the U.S. in 2002, and subsequently banned in Ontario.

The northern snakehead has a striking similarity to two kinds of native fish in New York State.  These fish are the bowfin (Amia calva) and the burbot (Lota lota).  There are differences in the fish that can help the angler or observer tell which fish is which.  The first difference is in the anal and pelvic fins.  Bowfins have a much shorter anal fin and the pelvic fins are more towards the center of the fish.  Like the snakehead, burbot have a long anal fin, but the pelvic fins are directly beneath the pectoral fins.  The next clue is the dorsal fin.  All three species of fish have a long dorsal fin, but you can tell the burbot apart from its two counterparts because there is a very noticeable break towards the front of the fish and makes two distinct dorsal fins.  The heads of the 3 types also look different.  The snakehead has a long, flat head (kind of like a snake), while the bowfin’s is round and broad and the burbot’s is slightly flat and they have a chin barbel.  If none of these pop out to you, you can always look at body color.  The snakehead is usually dark brown in color, with a coloration pattern that looks something like “old school” army uniforms.  Bowfins usually have a green tint and most of the time (but not all, so cannot always rely on this) possess a black “eye spot” on the tail near the caudal fin.  Burbot also have a dark brown color, but their color pattern is more spotted, kind of like a northern pike.

The northern snakehead has the potential to decimate rivers, streams, lakes and their tributaries with their high appetite for just about anything, high fecundity rate and adaptability to many kinds of environments.  They are not yet established in the Great Lakes or its tributaries, but they highly resemble the native fishes bowfin and burbot.  Any transportation or release of the snakehead is highly prohibited in the United States and Ontario for fear of them entering the lakes.  NYS anglers are asked that if they catch a fish that looks like a snakehead, to first check with the simple picture above.  If you are still not sure what the species is, take pictures, lengths, and weights of the fish and contact the nearest fish and game agency or the U.S. Fish and Wildlife Service as soon as possible.  If you are sure it is a snakehead, do not release the fish back into the water or throw it on the bank (they can live by breathing air and can wriggle back into the water).  Freeze the fish or put it on ice for a length of time to ensure the fish is dead.  If you catch one in an area where they are not known to live, contact the USFWS.  Always remember, it only takes a few individuals to establish a highly invasive population.  Keep yourself informed on these kinds of invasive species, and never release fish from your personal aquarium into an open waterway.

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Works Cited:

Fuller, P.F., A. J. Benson, G. Nunez, A. Fusaro, and M. Neilson. 2016. Channa argus. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
http://nas.er.usgs.gov/queries/factsheet.aspx?speciesid=2265 Revision Date: 9/22/2015

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