State scientists are studying their impact.
They ply the waters of the Potomac River with metal, spider-like prongs dangling off the bow of an aluminum johnboat in search of a voracious, piscine invader lurking in the shoreline’s shallows -- the Northern snakehead fish (Channa argus). John Odenkirk, a Virginia fish biologist, and several assistants have caught and studied snakeheads in northern Virginia every year from March to October since 2004 for the Virginia Department of Game and Inland Fisheries (DGIF).
The northern snakehead, a native of Asia that can reach 15 pounds, camouflages in vegetation and woody debris along the waterway’s edge. Their mottled brown hues easily blend into the plants, flotsam and muck.
“That fallen-over sycamore is great snakehead habitat,” Odenkirk said, pointing to a tree stretched across Little Hunting Creek on a recent morning outing.
He and his colleagues go “snakeheading” three times a week in Little Hunting, Dogue and Pohick creeks and the Occoquan River. They “electrofish,” a method that shoots pulses into the water, temporarily stunning all fish within a 6-foot radius. The gentle current causes the fish to float aimlessly for a few seconds near the surface and the researchers scoop up the targets with nets. The wily snakehead is not easily stunned or scooped.
“They fight hard,” Odenkirk observed, as a snakehead writhed to evade capture.
The year 2012 is pivotal for the snakehead project, Odenkirk said. In 2004, 2005 and 2006, his team’s mean catch rate rose every year at a “significant rate,” but in 2011 their catch rate was flat. That finding could be an anomaly.
“If it stays flat in 2012, that is very significant,” he said. If the
numbers level out, it could mean that the population has stopped growing and has maxed out with available habitat, that the local environment is at carrying capacity,” Odenkirk said. Reaching any conclusions now would be premature.
Why Catch Snakeheads?
DGIF scientists have been tracking snakeheads and large-mouth bass and analyzing impacts since 2004. They are examining size and abundance and changes from year to year. Odenkirk has recaptured 40 snakeheads to analyze
their growth rates.
Some anglers maintain that the snakehead is reducing the Potomac’s large-mouth bass population, a popular sport fish. Odenkirk explained that the two species have “dietary overlap”; they compete for the same food, like banded killifish, pumpkinseed sunfish and white perch. Both are top-level predators and in the spring, they share the same habitat, but Odenkirk has not confirmed a negative impact of the snakehead on bass.
“The Potomac River is amazing,” he said. “The watershed is productive. We are currently in one of the best large-mouth bass fisheries we have seen in many, many years based on catch rates in electro-fishing surveys and tournament-winning stringers.”
Odenkirk summed it up: “The snakehead is here to stay.” His message to the public is, “We still don’t want these fish moved around and present in other systems, but the early hysterics may have been a bit too shrill. Time will tell.”
The Snakehead Story
The northern snakehead was found in a Crofton, Md., pond in 2002 and exaggerations quickly went viral. Their ferocious appearance, snakeskin pattern, canine-like teeth and boundless appetite earned them the moniker “Frankenfish.” They could “walk on land,” some claimed.
No one knows how they got here, but theories range from home aquarists dumping them when the fish outgrew home tanks to intentional introduction for food. A popular food in Asia, they taste like pork chops, some say.
Invasive animals and plants are problematic because many can disrupt an ecosystem and some can outcompete native species. Snakeheads could alter the food availability and behaviors of other animals.
If You See a Snakehead
No one is required to report a snakehead, but DGIF requests that they be reported and killed if possible. Call 804-367-2925.
DGIF’s web site states, “If an angler wishes to keep a legally caught northern snakehead, the fish must be killed to be in possession, and the angler must call the hotline and report the angler's last name, date of catch, location of catch and size.”
It is illegal in Virginia to own a live snakehead without a permit. Federal regulations prohibit the importation of snakehead fish into the U.S. and prohibit interstate transport.
For more information, visit http://www.dgif.virginia.gov/fishing/snakehead-faq.asp and http://www.fws.gov/snakeheadfstotal.pdf.
Click here to see a video of Odenkirk working in Dogue Creek.