Sprol

Photo by Mohd Fahmi via Creative Commons

Snakehead fish are large, freshwater predators from the Channidae family that are native to Africa, Malaysia, Indonesia and various locations throughout Asia. These fish are plentiful in their native waters as there are some 28 varieties of snakehead fish.

The snakehead fish is very unique and different from the average fish. While they are similar, in body-type, to muscular eels, some snakehead varieties can grow to at least four feet in length. This fish got its name because of its stereotypically flat, snake-like head and toothed mouth.

What really make the snakehead so unique is its voracious appetite and its ability to breathe air. This fish is so adaptable, in fact, that it can travel short distances across land and live for short stents of time out of the water.

While there have been reports of snakeheads attacking and killing humans, they usually settle for fish, amphibians and small mammals. However, at least one species of snakehead, the Channa micropeltes, has been known to attack people when they approached the snakehead’s nest or their young.

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Over the years, these superb predators have found their way into the lakes and rivers of the United States, and this is where the problem of introducing a very adaptable, fierce predator into a new environment begins. The northern snakehead, or Channa argus, have been brought into the United States for two main reasons. There were going to be used as freshwater aquarium fish and as a specialty food.

It is reported that the northern snakeheads found in American waters are either illegally stocked in an effort to establish a local food source or aquarium owners eventually released the fish after they no longer wanted to or could care for them properly. Once introduced into their new homes, these fish tend to flourish.

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In fact, there are several species of Channidae that can tolerate a wide range of water temperatures. So, neither the warm waters of the south nor the cold waters of the north would prevent many snakeheads from becoming an established, yet undesirable, new resident.

Once established, these fish can expand their range by swimming to adjoining waterways or can even move short distances over land to nearby sources of water. The adaptability of these fish is not the only thing that makes them such a threat. The northern snakehead also breeds extremely easily.

Combine the northern snakehead’s adaptability, carnivorous appetitive, the ability to move over land and a lack of natural enemies, and you end up with a real and present threat to American waterways and the indigenous species of aquatic life that resides in these waters.

While this might not seem like a very significant environmental threat, the impact of releasing a pet snakehead or a food fish into local waters where that fish is not native is real.

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With no natural enemies in U.S. waters, the snakehead’s prolific breeding habits and hardy constitutions create a real potential for snakehead fish to multiply and destroy entire populations of fish and amphibians in the waters in which they are released. Many of these fish and amphibians are already on the endangered species list, and the snakeheads can only make things worse.

Consider this: At all stages of life, the northern snakehead competes with native fish and other aquatic wildlife for food. Native fish and wildlife populations, which already rely upon smaller fish, crustaceans, frogs, snakes, lizards and young waterfowl, will have to compete with these top-predators, and this could put them in great danger.

If snakeheads become established in a specific body of water, they can disrupt the ecosystem’s predator-prey balance. This can be catastrophic for native species.

Additionally, when a new species is introduced to an already established body of water, there is always the potential of the species bringing new diseases and parasites along with it. And, it does not appear that only large populations of snakeheads create environmental problems for American waterways. Even just one snakehead poses a threat because of its voracious feeding behavior.

In 2002, the United States Fish and Wildlife Service added snakeheads to the list of “injurious fish.” This means that snakeheads are prohibited from being imported into the United States.

Many states now even prohibit the possession of live snakeheads. However, these bans have not completely stopped illegal snakehead-activities, which have been recorded in most of the states where bans are in place. It is also reported that snakeheads can still be obtained over the internet.

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If snakeheads are found in the wild, the only means of eradicating the population would involve the complete eradication of the fishery with a piscicide, a chemical substance which is poisonous to fish. While this can be effective in small, isolated bodies of water, it does not generally work in large lakes or river systems.

This is what officials in Crofton, Maryland decided to do when northern snakeheads were discovered by anglers in 2002. This first Maryland snakehead was a long, skinny fish about 18 inches from end to end.

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Because the fisherman didn’t recognize the strange fish, he took a picture of it and put it back in the pond. Later, he gave the photo to the Maryland Department of Natural Resources (DNR). Sure enough, the fish was identified as a snakehead.

It wasn’t until another angler caught a snakehead in the same pond and netted some babies that officials really became concerned. Their concern was based on the fact that a heavy rain could possibly wash some snakeheads from the pond and into a nearby river, which runs through a National Wildlife Refuge and on to the Chesapeake Bay, the largest estuary in North America. Because of this, authorities acted quickly.

To eliminate the snakehead menace, Maryland wildlife officials dumped the piscicide rotenone into Crofton Pond. This succeeded in killing all of its fish. Six adult snakeheads and greater than 1,000 juveniles went belly-up, along with all of the pond’s native fish.. They thought the snakehead problem was solved.

Two years later, northern snakeheads reared their heads again, and this time they showed up in the Potomac River. Experts worried that snakeheads in the Potomac, by eating other fish or out-competing them for food, could drive down numbers of more desirable species, such as largemouth bass and shad.

Poison just wasn’t an option this time. You can dump poison in a little, enclosed pond, but you can’t very easily contaminate the entire Potomac in order to kill the snakeheads. It’s a wide, shallow river that originates in West Virginia and runs 380 miles before emptying into the Chesapeake Bay.

The Bay fuels the region’s economy through recreation and fishing. Snakeheads couldn’t survive in the mildly salty water of the Bay, but they could scarf down shad, fish that spawn in the Potomac and other freshwater tributaries. The complete eradication of the snakehead population would be nearly impossible.

To date, northern snakeheads have been found in U.S. waters in several states. One example was a snakehead that was hooked in North Carolina’s Paw Creek. This fish weighed 12.5 pounds and measured about 31 inches.

Because it is illegal to return a live snakehead fish to an American body of water, the fish was turned over to the Wildlife Resources Commission. However, this was not the first, and probably not the last, time a northern snakehead fish was caught in North Carolina.
Snakeheads have been caught in this area in 2002 and 2007. And, Paw Creek is an environmentally-dangerous place to have these fish because it straddles two lakes giving the injurious fish a lot of room to expand and invade.

The New York State Department of Environmental Conservation (DEC) Fisheries staff also responded to a report by a local angler of an invasive species in Catlin Creek near Ridgebury Lake in the town of Waywayanda.

The DEC recognized the danger of an infestation of northern snakehead fish. Left unchecked this predatory, invasive fish can rapidly expand its population and territory with real and negative economic impacts to the Hudson River watershed fisheries. Not to mention the fact that it can cause potentially irreversible harm to the rare and endangered species in the area.

Because of this threat, the DEC took immediate action in an attempt at containing the snakehead spread by erecting temporary fish barriers in Catlin Creek. DEC determined that swift action to eradicate this species is essential in protecting the native fish and amphibian populations and in preventing any further expansion of Northern Snakeheads beyond the headwaters of Catlin Creek.

It doesn’t appear that there is a quick fix to the Northern Snakehead problem. The key to managing snakeheads is to prevent them from becoming an established species in the first place. This may be difficult since they are already in U.S. waters and there numbers seem to be on the rise.