Asian carp threat
The silver carp and the bighead eat large amounts of plankton; in fact these two species can eat 10 percent of its total body weight in plankton each day. These two species of fish can weigh up to 45 kilograms, which is approximately 100 pounds. This means that they can eat almost 5 kilograms of plankton each day, which can be very devastating for the ecosystem of that region.
Michael Hoff, who is a biologist at the Fish and Wildlife Service, mentioned that this type of fish eats a lot more food than the local species, and he is concerned that the local fishes might be in the situation of not finding food. There is also the grass carp which will eat about 40 percent of his body weight, and this type of fish has been seen as well in the area. The grass carp will mainly eat aquatic plants.
The main problem with the Asian carps is the fact that they are eating constantly. Their stomach is not able to process the food and to provide the necessary nutrients which the fish needs. As a result these fish will eat constantly. Hoff said that the Asian carps have primitive digestive systems and as a result they eat constantly.
The planktons are very important for the fish because the fish collects the necessary nutrients by eating them. Since the Asian carps eat such massive amounts of planktons they can cause problems with the necessary nutrients. The Asian carps also have less natural predators than the native species of fish which can be found in the Great Lakes. Since the Asian carps consume the large amounts of planktons the sun’s energy which is collected by the planktons does not reach the native fish species.
Hoff said that they are like “energy sponges” since they consume all the fish which provides the natural energy and nutrients for the local species. He also mentioned that they eat and eat but no other species eat them. Most of the natural enemies feel threatened by the large sizes which these type of fish poses. Usually when a fish reaches 30 centimeters there are very slim chances for it to be eaten by its natural predators. The problem is that the Asian carp will reach this size much faster than the native species and as a result they have higher chances of surviving.
In the case of the other species of fish, many of them are eaten while they are young, but this not happens in the case of the Asian carps since most of their young are too big to be eaten by natural predators. The Asian carps do have natural predators which can consume them but once again there is a problem. Two of their natural predators, the catfish and the walleye spend most of their time at the bottom of the water, whereas the Asian carp spends its time more closely to the surface of the water. Because of this aspect, the predators have a really tough time catching them.
Another advantage which the Asian carps have is the fact that they reproduce much faster than the local species of fish, and once again because of this they have higher chances of surviving. One female of bighead carp has the possibility of laying 1.9 million eggs in a single year which is a very large amount. From this total number of fish only approximately 3% have chances of surviving. Even so, the number is way larger than in the case of the native species. Hoff said that because of this, the Asia carp simply invades the waters, consumes everything and as a result all the other species have to suffer.
Four species of Asian carps can be found in the United States of America, and these are the silver, the black, the bighead, and the grass. It is believed that they first entered the country’s waterways in 1960, when they must have escaped from the local fish farms. The first type of Asian carp which could be found in the United States was the grass carp, in the 60’s. The nest type found was the silver carp in the 70’s, and in the 80’s the first bighead carp was found.
The reason why the fish farms used these fish species was the fact that they were able to clean the water by eating algae and other harmful particles from the surface of the water. In the 1990’s there were large floods in the country and as a result many of the fish managed to escape into the Mississippi from the fish farms. Chapman mentioned that the flood was not responsible for the large number of Asian carps because even before the flood such fish could still be found in the US Rivers. Since they are so devastating, the Asian carps have become the main type of fish in many waters from the United States. It is estimated that the Mississippi river has the highest concentration of Asian carps in the world.
The Asian carps can now be found in the Missouri, Illinois River Basin and Ohio Rivers.11