Biologists from the Virginia Department of Wildlife Resources (DWR) stand ready on the bow, nets in hand, scanning for movement. They’re conducting long-term surveys for Channa argus, better known as the Northern Snakehead, a non-indigenous fish found in many Chesapeake Bay tributaries. Snakeheads are native to eastern Asia and were first discovered in Virginia waters in 2004. Since then, the species has established itself in creeks, rivers, and even reservoirs through illegal introductions. With funding from the Sport Fish Restoration Act (SFR), DWR has been collecting data and building one of the most expansive long-term snakehead research repositories to understand how the non-native fish are interacting with Virginia fish communities.

John Odenkirk, a fisheries biologist with DWR, received a call back in 2004 from a fisherman claiming he had caught a snakehead in a Potomac River tributary in Northern Virginia. This was not the first reported sighting, but other supposed snakeheads had turned out to be eels or native Bowfin. After driving an hour in Friday traffic Odenkirk met the angler and sure enough the man pulled a snakehead out of his boat’s livewell. While snakeheads had been confirmed in isolated ponds in Maryland, this 2004 capture was the first confirmed sighting in Virginia waters and the first snakehead confirmed in an open system of the Chesapeake Bay. “This confirmation ramped up the state’s work to learn more about snakehead,” says Odenkirk. “Good science informs good management, and we began surveying and collecting data on snakehead to better understand how the fish were introduced, how they survive, and how they are moving in rivers and tributaries.”

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For all their notoriety, snakeheads were still full of unknowns back in 2004. Published literature was very limited, and angler tales highlighted snakeheads resiliency and mystique. Equipped with a labyrinth organ that allows them to breathe air, these fish can survive in low-oxygen conditions where other fish might perish. They’re fiercely parental, building nests and guarding fry with a zeal most fish don’t bother with. And when it came to their diet, they don’t discriminate. Fish, frogs, and invertebrates were all known to be on the menu. But how would this species interact within Virginia waterways?

To find out, Odenkirk and his team at DWR began sampling several Potomac tributaries around the initial capture site including Aquia Creek, Pohick Creek, Dogue Creek, and Little Hunting Creek. These efforts included electroshocking waterways to collect snakeheads, conducting DNA analysis, examining otoliths (ear stones) to determine fish age, and even implanting transmitters into snakeheads for telemetry research. Their work, funded through federal excise taxes paid by tackle manufacturers, a portion of the fuel tax attributable to motorboat fuel use, and funds from state fishing license revenue, collected detailed data on snakehead population numbers, diets, movement patterns, habitat use, and if their presence would threaten the prized Potomac River largemouth bass fishery.

Telemetry research has been especially revealing. After biologists surgically implanted small radio transmitters in adult snakeheads, they tracked their movements for months. The team documented distinct seasonal shifts in habitat use with snakeheads sticking to submerged aquatic vegetation during the spring and summer months to give them cover for ambushing prey and nesting. Come winter, transmitters show snakeheads head into deeper channels.

DWR analyzed stomach contents of captured fish to build a clearer picture of snakehead diets in Virginia. Results suggest that while snakeheads do consume native species like killifish, the majority of their diet is bluegill, a non-native species whose population is doing well in Chesapeake tributaries. While sharing a prey base with bass, competition does not appear to be occurring due to lower snakehead abundance and an abundance of prey.

This type of information is vital for fishery managers. It can allow for targeted management strategies and show how the invasive populations are interacting in their new habitat. Perhaps most importantly, the research has shown that contrary to early media narratives and public fears, snakeheads are not invading every waterbody and that the spread of snakehead can be limited by salinity, barriers, and even habitat preferences.

“In many waterways it appears that snakeheads are coexisting with bass and other fish species, that they have limited available habitat, and that the snakehead population has started to plateau, and even decline, in some waters,” adds Odenkirk. One factor that may have helped with this plateau is angling pressure. Virginia anglers and bowfishers target them for their tenacious fight and for their firm fillets. Today, it is not uncommon to see snakeheads on the menu at restaurants in the Chesapeake Bay area.

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More than two decades after the first confirmed sighting, the work of the DWR has transformed initial uncertainty into a science-based understanding of this invasive species . Today, DWR has become a recognized expert in snakehead with other state fish and wildlife agencies reaching out for data and guidance as snakehead continue to reach new waterways across the U.S. Nearby fish and wildlife agencies in Maryland and the District of Columbia are also utilizing SFR funds to support programs related to snakehead. Further north, Delaware Division of Fish and Wildlife and New Jersy Fish and Wildlife use SFR funds to investigate and document snakehead sightings within their borders.

Thanks to consistent SFR funding and long-term monitoring, DWR biologists have tracked snakehead behavior, movement, and diet, helping to dispel early fears while guiding smart, adaptive management. “Snakeheads are established in Virginia and are here to stay,” says Odenkirk. “Thankfully, the research shows they are not the ecological disaster once feared. Instead, they’ve become a complex part of the ecosystem that can be managed with informed strategies and ongoing monitoring.”