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A team of researchers and interns at the Smithsonian Environmental Research Center discovered a northern snakehead fish (Channa argus) in Maryland’s Rhode River July 21. This is the first report of this species, native to eastern Asia, in this area. It may indicate a recent range expansion of the snakehead population.
A single northern snakehead was caught during routine sampling of a long-term study site using a seine net, representing the only specimen recorded for the Rhode River site in decades of surveys. This fish was a mature female, 23 inches in length, caught near the headwaters of the Rhode River. The first northern snakehead in Maryland was reported in 2002 in a Crofton pond, approximately 20 miles east of Washington, D.C. That population was eradicated, but a separate introduction occurred in the Potomac River in 2004, which led to the establishment of the Northern Snakehead in creeks and upper waterways of the Potomac in Maryland and Virginia.
The northern snakehead is typically found in freshwater, although it can tolerate low levels of salinity. It was thought that the higher salinity at the mouth of the Potomac could act as a natural barrier, limiting or reducing the fish’s spread to other tributaries. Due to extremely high levels of spring runoff in Upper Chesapeake Bay this year, salt levels in Chesapeake tributaries are at some of their lowest levels in the past 30 years. This has potentially allowed the fish to move out of the Potomac and travel to other rivers via the Chesapeake Bay.
Unlike most fish, the northern snakehead can survive up to four days out of water if kept moist. This ability comes from air chambers above their gills that act as a primitive lung. They are top-level predators with the ability to consume other fish and animals up to one-third of their own body size. Northern snakeheads may cause declines in local fish and other organisms, causing potential changes to the food web.
This most recently discovered fish was caught by a research team from SERC’s Marine Invasions Research Lab, which studies patterns and effects of biological invasions in coastal marine ecosystems throughout North America. The research team included three summer undergraduate interns working with the Invasions Lab under SERC’s Internship Program; these interns are an integral part of SERC programs and surveys. Research team members were research biologists Eric Bah and Stacey Havard, interns Philip Choy and Diana Sisson and visiting student Alison Everett. Information on this and other non-native species in Chesapeake Bay can be found at SERC’s website (http://invasions.si.edu/nemesis/chesapeake.html).
Any movement or possession of a live northern snakehead fish is a violation of Maryland law. People are asked to kill any northern snakehead fish they catch and contact the Maryland Department of Natural Resources or the Virginia Department of Game and Inland Fisheries:
Maryland Department of Natural Resources: (410) 260-8320 or toll-free at 1(877) 520-8DNR, ext. 8230.
Virginia Department of Game and Inland Fisheries in-state, toll-free at 1(800) 770-4951. Out-of-state callers reporting snakehead fish caught in Virginia waters should call directly to (804) 367-1258.
To view a fact sheet with a photograph of a northern snakehead fish and illustrations of similar-looking native species, people are encouraged to visit the following websites:
Maryland Department of Natural Resources
Virginia Department of Game and Inland Fisheries
U.S. Fish & Wildlife Service
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