Environmental effects of Snakeheads
 Environmental effects of Snakeheads


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Environmental effects of Snakeheads

The Snakehead species are not a natural part of the American ecosystem, and the first founding of wild Snakehead caused a lot of commotion. In May 2002, a fisher man caught a strange fish in Maryland, and handed over a photograph of it to a government office in Annapolis. The fish that he had caught and re-released in Crofton was soon identified as a Northern Snakehead.

The Northern Snakehead, Channa argus, lives in China and is highly adapted to surviving in areas exposed to seasonal dry periods. It is frequently found in shallow waters which can dry out completely during a longer draught. These waters are also typically very low in oxygen, and the Northern Snakehead will use its labyrinth organ to absorb oxygen directly from the air above the waters surface. This capability is also what makes it possible for the Northern Snakehead to travel far distances on land, using its strong body to wiggle like a snake over the ground in search for waters that has not yet dried out. The Northern Snakehead can survive for days out of water, and if it finds some mud it will burrow down and survive even longer while waiting for the rainy season.

In China, the Northern Snakehead is a part of a balanced ecosystem that has developed over the ages. Northern Snakeheads released on the American waters on the other hand, will encounter a new fauna where they are capable of causing a lot of disruption.

Ecologists are particularly worried about the already endangered American fish species; and for good reasons since the Northern Snakehead is a highly accomplished predator that feed mainly on other fish. The Northern Snakehead is however an opportunist and will happily eat almost anything, including plants, insects and crustaceans as well. The Snakehead thrives in marsh regions, slow-moving waters and densely grown ponds – habitats very common in the southern parts of the U.S. Even if released into an isolated pond far away from other waters, the Snakehead can use its labyrinth organ and strong body to wiggle its way over land to a new home if food become scarce or the pond is dried out. The Snakehead can sustain temperatures between 0° and 30° C / 32° and 86° F and would therefore flourish in a large part of the United States where winters temperatures below 32° F are uncommon. An abundance of prey and suitable habitats makes the U.S. a superb home for many Snakehead species, not just the Northern Snakehead.

Contrary to the natural migration performed by animals, the Snakehead would never be able to swim or wiggle its way to the U.S. It has been introduced to American waters by humans, most likely irresponsible aquarists or people who bought it as medication and ended up not consuming the fish. The Snakehead is considered a delicates in many parts of Asia, and is also an ingredient in several popular folk medicines. It is also a popular fish among American aquarists, since it is a fascinating and sturdy fish that will survive in most aquariums even when kept by inexperienced owners. Unfortunately, a lot of Snakehead keepers do not do any research about the fish before they buy it. They know that it is a though and somewhat aggressive fish, but do not realise that the Snakehead will quickly grow very big and require larger and larger aquariums. Their aggressive behaviour as the mature can make it impossible to keep them together. Another problem is that many people who buy a Snakehead do not realise that it is an expensive fish to keep. It should be fed a diet consisting of live fish, and it eats a lot! A small Snakehead that cost less than $ 7 to buy will soon grow up to be a large adult Snakehead that requires live fish for $ 7 – a day! Aquarists that find them self stuck with a large fish that they do not wish to care for anymore will unfortunately often release the fish into the wild instead of going trough the trouble of finding it a new home or euthanize it.

A huge, invasive predatory fish capable surviving out of water for days and walking on land naturally made the headlines in America when it was first discovered in Maryland, in May 2002. The media frenzy increased when it became known that this was not just a single occurrence. In the Crofton pond where the first examples was caught, several other adults where soon to be captured by anglers as well as by scientists. The first Snakehead was caught in May, and in the middle of July no less than seven other Northern Snakeheads had been removed from the pond. The most chocking new was however that six of these were juvenile Snakeheads – the Maryland pond was home to a breeding population. The smallest Snakeheads was only 5 cm (2 inches) long, which indicates that they were born in the pond and not released from an aquarium. The Asian Snakehead appreciated the environmental conditions in Maryland not just enough to survive, but to multiply as well. At the end of July, over 100 juvenile Northern Snakeheads had been caught in the Crofton pond. Ichthyologists estimated the young Snakeheads to be approximately five months old.

While many news papers wrote insightful articles about the potential environmental risks connected to invasive species, others resorted to more catching headlines about the gargantuan Asian predatory fish that could walk on land and breathe oxygen like a real world Godzilla. Lots of people were actually scared of Snakehead attacks on children and the public opinion demanded a rapid eradication of the Snakehead from U.S. waters. In August 2002, three months after the first catching in Maryland, a two-step process was initiated. The goal was to eliminate the Northern Snakeheads from the Crofton pond before they got a chance to multiply further and spread to nearby waters. During the first stage of the elimination plan, two types of herbicides were used in the Crofton pond to kill the vegetation and cause a severe drop of the oxygen levels. During the second stage, which was initiated two weeks later, a piscicide (fish poison) was introduced in an attempt to kill all remaining fish. New dead fish was removed each day and they surrounding area was anxiously monitored. After a few weeks, the water quality was tested and was declared normal again. No escaping Northern Snakeheads were sighted on the ground, but biologists suspected that some individuals might have managed to escape into the nearby Little Patuxent River. The Snakeheads would only have had to wiggle a distance of 75 feet (23 metres) to find Little Patuxent River. The Little Patuxent River was vigilantly sampled several times, but no Northern Snakeheads were found.

In October that same year, all 28 Snakehead species were formally added by the U.S. Fish and Wildlife Service to the List of Injurious Wildlife Species. All importation of Snakehead to the continental United is today banned, together with importation to Hawaii, the Commonwealth of Puerto Rico, District of Columbia and all other territory or possession of the United States. Even transportation of Snakeheads inside or between these territories is prohibited. A special permission to import Snakehead fish or eggs can be granted for scientific, medical, educational or zoological purposes, but such permissions are not easily obtained. U.S. Federal agencies are allowed to import Snakehead fish and eggs without applying for a permit, but only for their own use. Persons who keep Snakeheads must today apply for permission if they want to do any interstate transportation of fish or eggs. A lot of American aquarists keep Snakeheads since they ban on importation is just a few years old. Several Snakehead species are also easy to breed in captivity.
adult snakehead
Snakehead - Channa marulius.
Copyright www.jjphoto.dk

Unfortunately, the ban might have come too late. Maryland is not the only state where a breeding population of Snakeheads has been found. After the first startling discovery in Crofton pond, breeding populations of Snakehead has been found in both Florida and California, where the climate is warm enough for the Snakeheads to thrive once they are released into the wild. Individual Snakeheads have been caught all over the U.S., including such diverse states as Massachusetts, Maine, Rhode Island and Hawaii. The founding in Hawaii is especially troublesome, since Hawaii is already burdened with the plague of numerous other invasive species that threaten to eradicate the pristine and many times endemic flora and fauna of the island. Australia is another warning example that tells us how severe the impact of just a few invasive species can be to an ecosystem. It also a shows us how difficult it can be to eradicate, or even control, a species once it has been established. Even if the effects have not been as severe as on Hawaii or Australia, the United States mainland has in no way been blessed from problems invasive species throughout history.
The Snakehead is far from the first species to be introduced by humans to the United States wild life. The Kudzu plant for instance, is a high-climbing perennial vine from eastern Asia that was introduced as a garden plant in the U.S., where it lacked natural enemies and rapidly spread to the wild where it overgrew the native shrubs and trees.

The Snakeheads in America are especially dangerous to the already endangered fish species, but this does not mean that it is only a few rare species that could be harmed by the actions of the Snakefish. An ecosystem is always a complicated web where numerous factors interact with each other, and the introduction of a new species can disrupt the whole system. A new species can also bring along new parasites or diseases that can have an even greater impact to the natural balance than the species it self. In some cases, the introduction of a new species cause interbreeding with similar species; so called genetic pollution. One thing that is true is that it is almost impossible to tell beforehand what the result will be. We know that the Snakehead is an effective hunter and fear that it will multiply unhampered and consume a lot of fish, but we can’t know for sure. Maybe the Snakehead will blend in perfectly with the existing ecosystem. Maybe it will encounter some unexpected difficulties that obstruct its reproduction and makes and explosion of Snakeheads impossible. Maybe one of the American fish parasites will attack the Snakehead and make it vanish. However, since we do not know what will happen, most experts agree that the Snakehead should be eradicated from the U.S. wild life just to be on the safe side. To vigorously fight the Snakehead while the populations are still limited is much easier than trying to eliminate them when the first problems start to show up in 5, 10 or even 25 years time.

When we discus invasive species we must remember that the environments, the flora and the fauna of the planet Earth have never been static. Animals and plants have always spread from one area to another, and successful species will always strive to find new suitable living environments. If not for this process, the life forms that originated in the ocean billions of years ago would still be down there. Mankind has also spread species over the world for thousands of years; from involuntary transporting seeds under our feet to the planned introduction of new crops. During the last few centuries human travelling is however much faster, much more frequent and cover over larger distances than ever before in history. This means that a process that could earlier be a gradual change over centuries or even millennia, can occur much more rapidly. We should therefore be very careful and not introduce species in environments where we can’t foresee the short and long term effects of their impact. Most environments will eventually find a new equilibrium, but we might loose hundreds of native species in the process.

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Environmental effects of Snakeheads