Questions and Answers about the Northern Snakehead Fish

Northern snakehead Photo reprinted with permission of USGS, http://www.fcsc.usgs.gov/

Summer, 2007

The fish reportedly caught from the upper Catawba River arm of Lake Wylie on May 13 was recently confirmed as a northern snakehead (Channa argus), a highly predatory, invasive species.

Biologists with the N.C. Wildlife Resources Commission and United States Geological Survey identified the fish from a photograph submitted by an angler who said he caught the fish near Belmont. The angler mistakenly thought the snakehead was a bowfin and released it back into the river.

Northern snakehead, which are common in the aquaria industry and also sold live in some fish markets, are one of 28 species of snakeheads native to Asia and Africa. They can grow to more than 3 feet long and exceed weights of 15 pounds. They are aggressive predators that feed opportunistically on amphibians, fish, aquatic birds, and, on occasion, small mammals. Of greater concern is the snakehead’s ability to survive in waters with low dissolved oxygen and to travel across land. When looking for more suitable habitat, snakehead species have been known to leave poor quality waters and survive out of water for three to four days in search of other bodies of water.

In 2002, two northern snakehead were reportedly caught—and kept—from Lake Wylie. The discovery of a third snakehead has prompted questions from the public regarding snakehead. The Commission has put together a list of frequently asked questions to help address public concerns about this illegally introduced fish.

Q: Is there a reproducing population of snakehead in Lake Wylie or the Catawba River?
A: It is unknown whether the two northern snakehead reportedly caught from Lake Wylie in 2002 and the one from the Catawba River in May were part of a larger group of northern snakehead or if they are reproducing. No snakehead species has ever appeared in routine fish surveys conducted by fisheries biologists with Duke Power and the Commission. That doesn't mean snakeheads aren't in Lake Wylie or the Catawba River. It only means that fisheries biologists haven't detected snakeheads in Lake Wylie or the Catawba River to date. 

Q. If northern snakehead are in Lake Wylie or the Catawba River, do they pose a threat to humans?
A. No. We know of no reports of a northern snakehead attacking people. However, another species of snakeheads, the giant snakehead, has been known to act aggressively towards humans who have gotten too close to their young. It is important to note that the snakehead reportedly caught from Lake Wylie and the Catawba River were northern snakehead, not giant snakehead, which are a tropical species indigenous to Southeast Asia. The primary danger to humans would be not knowing what it is and encountering the teeth when trying to remove the hook. A much greater threat would be the ecological consequences should it become established.

Q. Assuming northern snakehead are in Lake Wylie or the Catawba River, how did they get there?
A. The two fish reportedly caught from Lake Wylie in 2002 were about the size of northern snakehead sold live in some fish markets and may have been released by a marketer or a buyer at a fish market into Wylie. The third fish reportedly caught from the Catawba River in May might have been a pet that had outgrown its aquarium or it may have been released by a marketer or buyer at fish market, as well.

Q. What is the N.C. Wildlife Resources Commission going to do about determining whether or not snakeheads are in the Catawba River?
A. After receiving the most recent report, Wildlife Resources Commission biologists sampled the catch-and-release site of the fish but found no snakehead. Along with routine sampling, the Wildlife Resources Commission is working to educate anglers and asking for their assistance. Public participation will be an effective tool in our efforts to assess northern snakehead in North Carolina.

Q. What will the Commission do if it finds northern snakehead in the Catawba River?
A: The Commission will work to evaluate where the fish are in the river and examine whether or not it’s possible to eradicate the fish. However, like with all introduced species, working to prevent illegal species introductions is our primary course of action.

Q: What has the Commission done to help combat the introduction of illegal fish species in North Carolina’s public waters?
A: In 2002, the Commission banned the transport, possession and release of all snakehead species in North Carolina. The regulation, which went into effect on July 1, 2004, makes it illegal to transport, purchase, possess or sell live snakeheads in North Carolina. 

There are additional fishing-related prohibitions for North Carolina waters.  
The Commission went a step further in 2005 when it passed a regulation that required anyone who wanted to stock a public, inland water to obtain a stocking permit first. Illegal fish stockings can have devastating impacts on native fishes. Preventing illegal introductions is much easier—and less expensive— than trying to eradicate non-native fishes once they’ve become established.

Q: What can the public do to help fight this invasive species?
A: The Commission asks anglers, hunters and outdoor enthusiasts not to transplant fish, game, non-game wildlife and plants. Exotic species of all types, not just snakeheads, pose a potential ecological risk when introduced into new ecosystems.
The N. C. Wildlife Resources Commission requests that anglers who think they have caught a snakehead, to keep it, freeze it or place it on ice and call the N.C. Wildlife Resources Commission at 919-707-0220. 

Q: How can I tell the difference between a northern snakehead and a bowfin, which it resembles?
A: The bowfin is native to North Carolina and resembles a northern snakehead. But bowfin, which are also known as "blackfish" and "grindle," do not pose the same ecological danger as the snakehead because bowfin already are part of North Carolina's aquatic ecosystems.
The pictures below should help with bowfin and northern snakehead identification. The best way to distinguish between the two species is to look at the anal fin, which is the bottom rear fin near the tail. The snakehead has a very long anal fin, which is more than half the length of the dorsal (back) fin, and has 18 rays. The bowfin has a shorter anal fin, which is less than half the length of the dorsal fin, and has 12 rays. 

The pictures below should help with bowfin and northern snakehead identification. A good distinguishing characteristic is the length of the anal fin (bottom fin) of these two fishes. While the bowfin has a short anal fin, the northern snakehead has a long anal fin.

Snakehead image reprinted with permission of USGS, http://www.fcsc.usgs.gov/

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