As assistant chief of fisheries for the Tennessee Wildlife Resources Agency, Bobby Wilson has grown used to receiving calls about strange fish discoveries in state reservoirs.
Most are no big deal.
So when he received word that a northern snakehead had been discovered at Shelby Forest State Park near Memphis, he assumed it was a false alarm.
But after talking with park manager Steve Smith, Wilson got worried. After seeing photos of the fish, he knew Tennessee had joined a growing list of states where the menacing snakehead has been discovered in public waters.
The 17-inch snakehead was found floating dead in Poplar Tree Lake on Dec. 12 by off-duty sheriff's deputy William Nelson and later verified by University of Memphis professor Dr. Jack Grubaugh. TWRA officials will begin electrofishing studies soon to see if the voracious predator was alone or if others are present in the 125-acre lake.
"My first thought when I got the call was that somebody had caught a bowfin, which looks something like a snakehead," Wilson said. "But after talking with Steve, it was obvious ... this fish was not a bowfin."
A native of China and Southeast Asia, the northern snakehead is one of the most efficient predator species on Earth. Sometimes referred to as the "coyote of the aquatic world," snakeheads often reach lengths of 4 feet and have virtually no enemies in the wild.
The fish have rows of jagged teeth and will readily consume whatever they can catch, meaning they can wreak havoc on native fish populations. Snakeheads are capable of breathing air and can survive several days out of water. They sometimes travel over land from one body of water to another.
Snakeheads were first discovered in the United States in a small Maryland pond during 2002. They have since been found in Florida, North Carolina, Virginia, Pennsylvania, California -- and now Tennessee.
"This is not like finding a pacu or a goldfish or an Oscar fish," Wilson said. "Those species are unusual. But for the most part, they're harmless. The snakehead has the potential to cause a wide range of ecological problems."
Pacu, goldfish and Oscar fish -- three species that are often released into public lakes by aquarium owners -- are tropical fish that rarely survive the cold water temperatures of a Mid-South winter. But snakeheads are adaptable and plenty capable of surviving frigid water.
Because the fish found at Shelby Forest was dead, Wilson said it may have been released by an aquarium owner when it outgrew its tank.
"If there is a positive side to this, it's that the fish was floating dead," Wilson said. "That could mean that it had been living in an aquarium and was used to being fed by hand. Once it was forced to find food on its own, it couldn't survive."
Wilson said TWRA officials had originally planned to wait until water temperatures rise and fish become more active before they begin using electrofishing boats to look for more snakeheads. But they decided to begin searching within the next few weeks.
If more snakeheads are discovered, drastic measures could be necessary. Other states have been forced to drain lakes the size of Poplar Tree Lake to eliminate snakehead infestations.
"We're already having a lot of problems in Tennessee with Asian carp and Zebra mussels. We don't need the snakehead added to that," Wilson said.
Grubaugh, an associate professor of biology at UofM, still has the fish in his freezer. He said it seems likely the snakehead was the only one of its kind in Poplar Tree Lake.
"I'm really basing that assessment on a whole lot of nothing," Grubaugh said. "But given the fish's size, I suspect it was thrown into the lake by an aquarium owner and went belly up right away. If there had been any kind of spawning activity, people would have noticed it before now."
Snakeheads are listed as an "injurious to the environment" species in Tennessee and are illegal to possess. It is also against the law to release a snakehead or any live fish species into Tennessee waters unless it was caught from that body of water.
Native to China and Southeast Asia.
Adaptable to almost any environmental conditions.
Can tolerate low oxygen conditions in water because they are air breathers.
Can survive cold water temperatures, sometimes even living under frozen surface water.
Can live out of water for up to four days.
Capable of migrating short distances by "wriggling" across the ground on their bellies.
Females spawn as many as five times a year.
Often sold as food in the Asian-oriented fish markets of the eastern United States.
Popular in the aquarium trade because they are easy to transport and survive easily in tanks.
Because snakeheads are such voracious predators, they pose a high risk to many native and endangered species