NEW YORK -- The Harlem Meer, in the northeastern corner of Central Park, has long been a refuge for city people looking to indulge their inner Huck Finns, whiling away a lazy summer afternoon fishing for bass, yellow perch and crappies.
Late last week, though, signs started popping up around the lake notifying anglers of the arrival of an intruder. The dreaded northern snakehead, a fierce predator common in the rivers and lakes of Asia but considered an invasive species in U.S. waters, had been spotted.
The warning to anglers was clear: If you catch this fish, do not release it. Contact the authorities immediately. It does not belong and could radically alter the local fish population.
The snakehead is a relentless and efficient predator that devours just about everything in its path -- fish, frogs, crayfish, beetles and aquatic insects. And it does not meet death easily; it is able to survive under ice or live on land for days in damp conditions. It has been called Fishzilla.
"I would describe them as the freshwater-fish equivalent of a tank," said Ron P. Swegman, a fly-fishing expert and author whose writings about fishing in Central Park include an essay, "Bright Fish, Big City."
"They are heavily armed," he said, "strong, and can cover almost any territory, aquatic and -- at least for short periods -- on land."
Snakeheads, which can be more than 3 feet long, are known as voracious eaters and prodigious breeders.
Mr. Swegman said the local fishing community was obsessed with the fish, with regulars even wagering on who would be the first to catch one.
When he was fishing with a friend on the lake in late April, just as the signs started to appear, the friend claimed to have hooked one, reeling it in close enough to see, before it escaped. "That is a true story," Mr. Swegman said.
Last week, the New York State Department of Environmental Conservation was due to begin a survey of the lake. They will try to verify the sightings, determine how many snakeheads there might be and gauge the threat it poses to other wildlife.
State wildlife officials were planning to use an electro-fishing boat, which releases an electric current just beneath the vessel to temporarily stun nearby fish. The fish can then be scooped up in nets and examined on shore.
"We got a call a few months ago that an angler might have caught one," said Melissa Cohen, a regional fisheries manager for the department, but that report was unverified. More recent reports prompted park officials to put up the signs.
If snakeheads have established themselves in the lake, she said, someone probably released them there, perhaps hoping to create a population for later fishing.
The threat posed by the fish, which is common in the lakes and streams of China, Korea and Russia, should not be underestimated, wildlife officials said.
The possession, sale and transport of live snakeheads was prohibited by federal law in 2002. However, they remain a persistent presence in Chinese fish markets across the city, officials said. For many, the fish is prized not only as a meaty, savory ingredient in stew, but also for its supposed healing properties.
After the seizure of 353 live snakeheads at Kennedy International Airport on the eve of the 2010 Chinese New Year, an investigation led to the arrest of a local wholesaler in 2011 who illegally imported thousands of snakeheads and sold them from a shop in Brooklyn.
Ms. Cohen said that a single snakehead turned up in the Harlem Meer in 2008 and that the fish had recently established a presence in Meadow Lake in Queens.nation - huntingfishing