Officials yesterday said the voracious northern snakehead fish is breeding in the Potomac River after this week’s discovery of a sexually mature specimen in a northern tributary.
“Up to this point, most of the snakeheads were immature or starting to mature sexually,” said John Odenkirk, a biologist from the Virginia Department of Game and Inland Fisheries (DGIF). “This fish is sexually mature. … Reproducing has been occurring for some time here.”
John Kauffman, Virginia’s regional fisheries manager, said the discovery of the first adult snakehead in the Potomac adds “growing evidence of an established population” of the toothy, nonnative fish.
With its ravenous appetite and having no natural enemies, the snakehead can disrupt an ecosystem by preying on all other fish in it. The specimen caught Thursday was the sixth found in Potomac waterways this spring.
According to Bob Lunsford, a biologist for Maryland’s Department of Natural Resources (DNR), the long-term effect of the snakehead is not clear. He said the snakehead could compete for food with the region’s small-mouthed bass, a popular recreation fish.
“That’s the great unknown,” Mr. Lunsford said. “We just don’t know, and we’re not excited to find out.”
The snakehead was caught in Little Hunting Creek in Fairfax County. It was 3 to 5 years old, measured 24 inches and weighed 5 pounds. The five specimens caught earlier measured 12 to 14 inches.
“The bottom line is, this is big,” Mr. Odenkirk said.
Native to Asia, the snakehead can grow up to 3 feet, live out of water for up to three days and move across land by using their pectoral fins.
“Before yesterday, we didn’t think it would be able to breed this summer,” said Mr. Lunsford, noting that the newly caught specimen was starting to show sexual development.
Biologists had hoped the extra year needed to reproduce would slim the northern snakehead’s chances of survival.
Even if the snakehead becomes established in the area, it could take years to see its effect on the ecosystem, Mr. Odenkirk said.
Maryland and Virginia are collaborating with federal agencies to monitor the snakeheads.
Wildlife researchers are awaiting results from DNA tests comparing the snakeheads from the Potomac to those found in a Crofton, Md., pond in 2002.
Mr. Lunsford believes it is unlikely the snakeheads found in the Potomac came from any of the 1,300 found in Crofton because only six or seven of the snakeheads caught in there were adults.
“This is some sort of additional release,” Mr. Lunsford said.
This article is based in part on wire service reports.