In Jingjiang City, Jiangsu Province, a boy was bitten by an alligator eel in a pond in a neighborhood and injured his finger.
And Jordan Field, a 19-year-old young man in the United States, was in the Illinois River when suddenly a big fish flew out of the water like a missile and smashed into his face. The fish broke his nose, dented his forehead, and shattered the bones of his eye sockets and forehead). Jordan commented, "If it hit me harder, it could break my skull, seriously damage my brain and kill me on the spot".
The fish that caused this was the invading Asian carp, which flooded the Illinois River and its surrounding waters, including the Mississippi, Missouri, and Ohio rivers. Carp are easily frightened by boat motors or other loud noises that cause them to jump out of the water, turning their large bodies into dangerous projectiles that can obviously hurt people along the way.
An Asian carp that is frightened by the motor and churns
Ecosystems have a delicate balance, in which organisms work harmoniously, each occupying their own niche, and when a new organism enters the ecosystem, they can occupy the niche of another species, competing with them for resources and food. Unfortunately, native species often lose out to new invaders. The National Invasive Species Information Centre defines an invasive species as "a non-native (or alien) species of the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental damage or damage to human health". One of the invasive species, the Asian carp, has gained prominence in the United States and was introduced for phytoplankton control and aquaculture.
Native American carp species have been around for more than 100 years, and species known as "common carp" live here with little environmental impact. The newer and more powerful Asian carp describes 4 different species, namely bighead carp, grass, black and silver carp. The United States imported silver carp and bighead carp from Asia in the 1970s for research purposes, placing them in wastewater lagoons and aquaculture ponds to see if they improved water quality. Federal and state agencies, general citizens and researchers imported and introduced grass carp from East Asia in 1963 to control aquatic plants in fish farms. Juveniles came to the United States, initially in Arkansas, in the 1970s, when they arrived with a herd of grass carp. No one noticed because the appearance of juvenile and grass carp was almost the same. The United States is trying to use bluefish as a food resource and to control yellow grubs in aquaculture ponds. Flooding events in aquaculture ponds connected to rivers have caused silver carp, bighead carp, grass carp and blackfish to flee to the Mississippi and Missouri rivers, where they now establish breeding populations
The invasive Asian carp showed a trend of rapid increase in numbers shortly after its introduction. In South Dakota's Missouri River, the abundance of Asian carp soared from 2009 to 2012. In 2009, a fishing survey on the Missouri River did not catch Asian carp. By 2012, fishing surveys had caught 35 fish per hour. In six sections of the Mississippi River, the number of Asian carp caught fell from less than 50 per hour in 2003 to 775 per hour in 2012. This 15-fold increase shows that Asian carp was able to flood an area in just 9 years.
Asian carp often competes more for food than native species. Asian carp filter and greedily consume algae and zooplankton, which are the main food sources for native fish such as herring, white sturgeon and largemouth buffalo. Small zooplankton such as rotifers make up a large portion of the diet of many native filter-eaters, but Asian carp also eat them. In a section of the Mississippi River, The Asian carp reduced the number of rotifers from 6,000 per liter of water in 2002 to 3,500 in 2003, a nearly 50% reduction in just one year. As a result, the number of available prey is reduced and predatory species are forced to feed more on other organisms, such as copepods, which many fish eat little but make up nearly 62% of the diet of the endangered white sturgeon. Sampson et al. observed a decrease in rotifer abundance. This means that fish will have to hunt for and eat different prey, rather than relying on rotifers as Asian carp used to do.
Asian carp reduces the abundance of native species they colonize. In 2009, Asian carp accounted for less than 1 percent of the Missouri River catch, while native emerald mackerel accounted for about 30 percent of the 2009 catch. In 2012, Asian carp accounted for 50% of the catch, emerald mackerel fell to 5% of the catch, equivalent to a 6-fold reduction in emerald luster and a 50-fold increase in Asian carp. In the Mississippi River, Asian carp caused a 10 percent reduction in the largemouth buffalo population, rather than following the historically observed 35 percent increase. After the invasion of Asian carp, the number of buffalo caught per hour decreased from 178 to 85. In another study of the Illinois River, the largemouth buffalo population fell by 80 percent in 2005, compared to the abundance recorded for fishing trips in 1995. In the same section, the annual catch of Asian carp increased from 0 in 1995 to 500 in 2005
One reason carp has become so abundant is that native predators don't like to eat Asian carp. When choosing between the two, native fish show a preference for native prey. Native fish-eaters in the Mississippi River Basin showed a negative selectivity or preference for silver carp. Of the white perch tested in this study, Asian carp was selected only 3 times out of 29. Studies have shown that out of 29 times, largemouth bass choose to eat Asian carp first instead of local prey only 4 times. However, largemouth bass did show a positive choice of 0.23, specifically for grass carp, but they still had an overall negative selection of -0.08 for Asian carp.
In this study, a score of 1 represents the highest selectivity for eating Asian carp and a score of 1 represents complete avoidance of Asian carp. Studies have shown that all native fish-eaters have little or no preference for Asian carp except proboscis, which has a selection rate of 0.12 for Asian carp. The low selectivity of U.S. fish to Asian carp suggests that the use of predators to control the infestation of Asian carp in U.S. waters can only be successful by deploying one of carp's natural enemies into a new environment in the United States. The low selectivity of U.S. fish to Asian carp suggests that the use of predators to control the infestation of Asian carp in U.S. waters can only be successful by deploying one of carp's natural enemies into a new environment in the United States. The low selectivity of U.S. fish to Asian carp suggests that the use of predators to control the infestation of Asian carp in U.S. waters can only be successful by deploying one of carp's natural enemies into a new environment in the United States
However, since none of the natural enemies of Asian carps live in the U.S. water system, all Asian carp predators will also become invasive species in these ecosystems, and their implementation in U.S. waterways could cause further ecological impacts that are as bad or worse as the negative impacts followed by infestations of Asian carps.
So it's clear that Asian carp can cause problems wherever they invade. People are not turning a blind eye to this and have done something to try to counter their invasion. The Army Corps of Engineers set up electric fences along the Chicago Canal to prevent them from moving upstream, which was bad for two reasons. First, it prevents native fish from moving along the river, and second, the power to the fence has been turned off and carp pass by it. Another option is to pour poison into the river to kill the carp. This is bad because it could kill all native species, and pouring poison into a river will only take it farther upstream, affecting more than just the target area. In addition, sometimes poison does not work.
Then the Yankees had a new proposal: to add predator-alligator eels to the U.S. waterways to fight Asian carp.
There is a predatory fish known as the alligator eel in the southeastern United States, which many scientists believe could serve as an effective predator for Asian carp. Using native predators can prevent any negative impacts that other invasive species may have on the U.S. waterways. Alligator eels once existed in the Mississippi River and its tributaries, from Ohio all the way to Illinois and all the way to the Gulf of Mexico. However, the main reason they now only live in the Mississippi River Basin from Arkansas to the south is that the large decline in the population of alligator eels is humans.
For example, many people consider the alligator eel to be a "garbage fish" that is not as valuable as commercial game fish and target them for elimination and control. Some of the other major reasons humans attack finches in this way include that they are a large, monster-looking fish that is thought to attack humans and is thought to deplete the number of commercial predatory fish. In addition, alligator eels do not eat many fish because they are opportunistic predators that will eat anything that swims within their reach, and most prey fish are relatively agile, which means that if crocodile gar eels want to eat them, they must hunt them, which is not their nature.
Clearly, before considering the feasibility of re-introduction of alligator eels, policymakers should determine whether the reintroduction of alligator eels can have an impact on Asian carp stocks in U.S. waters. The alligator eel is one of the largest freshwater fish in North America and the largest fish in the Mississippi River Basin. Alligator eels are generally 1.2–2 m long and weigh 45–72 kg. The largest crocodile finches ever caught and officially recorded are 2.6 m long and weigh 148 kg
On the other hand, Asian carp is found throughout the ecosystem, and the four species of Asian carp that invade the U.S. waterway can grow to 30 cm to 100 cm and weigh 10–40 kg. When ripe, Asian carp can reach a maximum size of 1.2 m and weigh 45 kg. Consider that the largest alligator eel can grow up to 3 times the weight of the largest Asian carp on the U.S. waterways.
Crocodile eels do not have the function of chewing, they can only eat by swallowing, up to 1/4 of the body's food.
Many people, including Dan Stie, a biologist and fisheries director at the Illinois Department of Natural Resources, say their jaws won't open large enough to accommodate most Asian carp.