Recently, a "strange fish" more than half a meter long was fished out of a small area of Beijing, and professionals confirmed that it was a ferocious fish from the Americas, the alligator eel, which belongs to an invasive alien species. This fish wandered in the water system of the community for many days, and the property was repeatedly organized to salvage unsuccessfully, and then it was fished by an owner and finally handed over to the relevant departments.
According to media reports, a "water monster" has also appeared in a park in Henan recently, and the park is highly suspicious of the crocodile eel that was released. It is reported that the fish is 70 to 80 centimeters long, and the garden organized a fishing but did not succeed in catching it.
In fact, it is not uncommon for alligator eels to appear in domestic waters. According to reports, Guangdong, Guangxi, Fujian, Henan, Sichuan, Jiangsu and other provinces have recorded the wild distribution of crocodile eels. Experts say that the alligator eel has a strange body shape, fierce personality and large size, and can be regarded as the most dangerous alien invasive aquatic organism. Experts suggest that alligator eels should be included in the national list of invasive species under key management.
From August 1 this year, the "Measures for the Management of Invasive Alien Species" came into effect, which is the first management measure for the prevention and control of alien species in the mainland, which stipulates from the aspects of source prevention, monitoring and early warning, governance and restoration. The management of invasive alien species has attracted wider social attention.
Alligator eel: Preys on other fish, almost all kinds of harms and no benefits
According to the data, the alligator eel is a freshwater giant carnivorous fish specialized in southern North America, which is a prehistoric fish that has lived on the earth for more than 100 million years. The alligator eel is a genus of finches, finches, and large eels, and is the largest of the 7 extant species of finches. Because the tip of the mouth resembles a crocodile, densely packed with sharp teeth, and the attack power is directly full, it is called the crocodile eel.
Gu Dangen, an expert in the prevention and control of alien species invasion in the national bulk freshwater fish industry technology system, has been paying continuous attention to invasive fish, and he introduced to reporters that there are 7 species of gar, from the north of South America to the south of North America. At present, the most common in our country are crocodile eel and spotted gar, of which alligator eel appears more frequently in natural waters. Among the two species of gar, the alligator gar is the largest, fiercest, and most dangerous.
It is reported that the crocodile eel can reach a maximum of 3 meters, mainly feeding on other fish, and has strong predatory properties. "It's a very tough fish," Mr. Gu said.
A crocodile eel captured in Foshan City Park in 2019. Courtesy of respondents
Gu Dangen said that in the past two years, he had received two crocodile eels from others after fishing in the park lake, and those two were more than 100 pounds each at the time, more than one meter long.
Talking about the harm of this fish, Gu Dangen once said: "Crocodile eels can eat almost all the fish in their habitat (of course, small water bodies are realistic), and in the case of insufficient food, cannibalism is common for them." ”
Li Li, director of the Beijing Panther Wildlife Conservation Station, said that if the crocodile eel is released into the waters south of the Yangtze River, it will bring devastating disasters to wild animals in local areas, which is quite dangerous. Crocodile eels can lay more than 150,000 eggs, and when they reach temperature and humidity conditions, they will grow rapidly and eat native fish.
In addition to destroying the ecology, crocodile eels can also cause economic losses.
Gu Dangen told reporters, "If the breeding waters are mixed with crocodile eels, it will basically be harvested, which will make the farmers lose their money." ”
And the economic value of the alligator eel itself is very limited. Zou Qiangjun, a senior engineer at the Beijing Aquatic Wildlife Rescue Center, said in an interview with reporters earlier that the scales of the crocodile eel are very hard, as if wearing a suit of armor, which can resist sharp blades, so it is very difficult to obtain fish meat from such a "fully armed" fish; Moreover, the eggs and ovaries of crocodile eels are highly toxic to mammals, including humans, and poisoning accidents will occur if they are not carefully consumed.
"In addition to bringing certain benefits to some fishmongers, crocodile eels have no role in promoting the industry at all, but the negative impact on the entire country and the entire ecology is too great." Gu Dang'en said.
Crocodile eels also have a certain degree of aggression, according to Li Li, if the body size is basically fine, but the size of the body, it may attack poultry. However, if you encounter an alligator eel, you don't have to panic, and there are fewer cases of attacking people at present.
How could this creature, which was almost harmless and unprofitable, come to the continent from the distant Americas?
Li Zhenyu, a researcher at the State Key Laboratory of Systematic and Evolutionary Botany at the Institute of Botany of the Chinese Academy of Sciences, said that some invasive alien species are intentionally introduced, such as for consumption or ornamentation, "like Fushou snail was originally introduced to eat, and later found that it did not meet the taste of Chinese, did not have economic value, and was abandoned after breeding, flooding in the wild." "Others are unintentionally introduced and inadvertently carried to new areas to create hazards.
"Alligator eels are introduced as ornamental fish." Gu Dangen introduced, "Its body shape is more peculiar, more fierce, can meet people's curiosity, so many people like to raise this." Crocodile eels should have been introduced for twenty or thirty years, and there were artificial breeders at the latest in the early 2000s. ”
Gu Dangen once said, "In the early days, most of the crocodile eels were smuggled illegally, and due to the lack of supervision, it is not difficult to buy alligator eels in the ornamental fish market." ”
"After a large number of crocodile eels are artificially farmed, they are often artificially released or discarded because the growth rate is too fast, the aquarium cannot be accommodated, or they cannot afford to pay the cost of breeding. Others are artificially released. Gu Dangen said.
He told reporters that at present, the distribution of crocodile eels on the mainland is very wide, mainly in the Pearl River area has established a population. In Guangdong, crocodile eels are more common, especially in Guangzhou, Foshan city park lakes most of the crocodile eels, some rivers also have crocodile eels. "The discovery of alligator eels in Guangdong, I think it should not be news." But every time it comes out, everyone is more sensitive. ”
Last month, an old fisherman in Guangzhou's Panyu District gave Gu Dangen the crocodile eels he caught from the Pearl River 15 years ago, "This fisherman has been raising this fish for 15 years, saying that the Pearl River water system had this fish 15 years ago, but it is relatively small and rare." ”
Old fishermen in Guangzhou's Panyu District have been raising crocodile eels for 15 years since fishing in the Pearl River. Courtesy of respondents
Gu Dangen said, "In recent years, I have clearly known that there are hundreds of crocodile eels, which have gradually increased since 2018, and have blossomed almost everywhere in the country." "This also includes Beijing, where there are relatively few records and reports of crocodile eels, and the news of crocodile eels fishing from the Water System of Beijing Community has once again attracted public attention." According to existing reports, from Guangdong, Guangxi, Fujian to Henan, Sichuan, Jiangsu and other provinces have recorded the wild distribution of crocodile eels.
Difficult to control: Online and offline are easy to buy, and it is difficult to capture organisms in water
"There is a fundamental difference between alien species and invasive alien species." Li Zhenyu said. Alien species are species that are extraterrestrial and are unnaturally transported to places inaccessible by natural transmission. Extraterritorial "domains" are as large as the hemisphere, such as from the eastern hemisphere to the western hemisphere, and as small as regions such as from other provinces to Beijing. Some beneficial alien species, such as corn, wheat, sweet potatoes, etc., "even saved the lives of the chinese people, brought significant economic value, and helped solve the problem of food and clothing for Chinese." Li Zhenyu said that alien species are neutral, whether beneficial or unhelpful, just a concept of biota. Invasive alien species simply refer to the formation of ecological disasters, economic losses or harms to human health in new areas.
According to Gu Dangen, aquatic alien species, if only cultivated in ponds or aquariums and other controllable water bodies, will not form a hazard. If it is released into natural waters, it cannot overwinter and reproduce, then its harm is short-lived and cannot be defined as an invasive species. Only those that can naturally reproduce in natural waters and form harm are called invasive alien species. Crocodile eels were previously relatively small in number, but after long-term monitoring in recent years, it has been found that it can establish natural populations in many southern watersheds, and it has also formed a hazard, so it has been classified as an invasive alien species.
Invasive alien species need to be managed, but they face certain difficulties in governance. For alligator eels, the difficulty of governance can be summarized as two reasons.
First of all, alligator eels can be easily purchased in online and offline markets.
Previously, the reporter visited a flower, bird and fish market in Chaoyang, Beijing as a consumer and found that there were about 6 shops selling crocodile eels, and many sellers told reporters that crocodile eels were very well fed.
There are also crocodile eels for sale on the Internet, and there are stores where the monthly sales of crocodile eels are more than 1,000, and the list price ranges from 10.8 yuan to 400 yuan.
"Trade is unregulated and can be bought at will. Buyers are more dispersed, the distribution is wide, as long as there is one in each place, the harm may be relatively large. Gu Dang'en analyzed. Once the bought alligator eel is discarded or released into natural water, the hazards follow.
Secondly, after the alligator eel enters the water body, it is not easy to find, and there is no way to catch it if it is not seen.
"If alligator eels are found in rivers, lakes or reservoirs, it is basically impossible to remove them. Because the water body is too big, like that dozens of acres and hundreds of acres, there is no way. You can't drain the water at every turn for a crocodile eel, which is too expensive. Gu Dangen said.
Crocodile eels that have recently appeared in the water system of Beijing residential areas have repeatedly evaded the fishing of property staff. The owner who caught the fish reportedly squatted nearby for several days in order to catch it.
In 2021, the Ministry of Agriculture and Rural Affairs, the Ministry of Natural Resources, the Ministry of Ecology and Environment, the General Administration of Customs, and the State Forestry and Grassland Administration jointly issued the Work Plan for Further Strengthening the Prevention and Control of Alien Species Invasion, mentioning that "strengthen the supervision of the breeding of aquatic alien species, and promote the comprehensive management of aquatic invasive alien species such as water hyacinth, Fushou snail, crocodile eel and so on." The document explicitly refers to the "alligator eel".
"Led by the Ministry of Agriculture and Rural Affairs, the Ministry of Natural Resources, the Ministry of Ecology and Environment and other ministries and commissions will soon launch a new list of invasive species under national key management, and we firmly recommend that we put it in." Gu Dangen revealed to reporters.
It is reported that the aquatic invasive alien species that will be included in the new "National Key Management List of Invasive Alien Species" include Brazilian turtles, large alligator turtles, "scavenger fish" (scientific name leopard striped winged catfish), Qi's tilapia and so on.
The treatment of invasive alien species has become urgent, and when Li Li patrolled and monitored the Juma River, one of the five major river systems in Beijing, he found that crocodile turtles had already appeared in the area. "In the summer, you can see a few crocodile turtles basking in the sun on the beach, and sometimes you can hear the call of bullfrogs."
"The Brazilian turtle and the alligator turtle, which have a high survival rate and a shorter growth cycle than the native turtles, grow particularly fast, and will compete for food for native species and squeeze the living space of native species." Li Li said that some of the Brazilian turtles and alligator turtles may be able to survive the winter in Beijing, which is a very bad development direction.
Li Zhenyu told reporters that the ecological harm of these aquatic invasive species is typical, "If you accidentally put your hand in front of the crocodile turtle, it may directly bite off your finger." ”
Like the alligator eel, it is not easy to control these invasive aquatic alien species. "We found alligator turtles or Brazilian turtles on patrol, which are generally not caught because they are very sensitive and usually choose to inhabit places that are conducive to escape, such as their heads facing the water. As soon as you get a little closer, it instantly slides into the water. Li Li sighed, "Aquatic animals, it is difficult to catch." ”
As for aquatic invasive alien plants, their harm cannot be underestimated. Not only will it damage the ecology, "in severe cases, aquatic plants will block the channel, such as the interfluille rice grass may entangle the propellers of fishing boats." Floating plants such as water hyacinth are easy to find, but submerged plants live underwater and you can't see them at all. Li Zhenyu introduced.
Gu Dangen believes that aquatic invasive alien species are more difficult to find and more difficult to remove. Because the circulation is relatively strong, the water body is basically passable, and these species are easy to spread. Second, invasive species that live in water are more difficult to spot than land-based organisms, often too late to be discovered. In addition, aquatic organisms are also more difficult to catch, and invasive organisms in water bodies, especially animals, cannot cut off rivers or drain water to remove them, nor can they remove all aquatic organisms in order to kill invasive alien species.
According to the 2019 Bulletin on the State of China's Ecology and Environment issued by the Ministry of Ecology and Environment on June 2, 2020, more than 660 invasive alien species have been discovered nationwide.
The harm of invasive alien species deserves attention. Public information shows that the mainland is one of the countries most endangered by the invasion of alien species. Taking the invasion of forest harmful organisms as an example, the average annual area of the "Eleventh Five-Year Plan" period was 170 million mu, resulting in direct economic losses and ecological service value losses of 110 billion yuan, of which the most serious harm to pine wood nematode, American white moth, etc. caused by the average annual loss of forestry was as high as 11 billion yuan.
Governance to break the situation: we must control from the source, we must start from the grassroots
In the case of the alligator eel, "it is necessary to control death from the source." Gu Dang'en stressed.
According to the Beijing Customs staff, according to the provisions of mainland laws and regulations, imported aquatic animals should be included in the access list published by the General Administration of Customs according to their use after entering the country, such as edible, seeding or ornamental, and the "Quarantine Permit for Imported Animals and Plants" can only be completed before the signing of the trade contract or agreement.
The reporter's inquiry found that the list of countries or regions and varieties of aquatic animals that have been admitted on the official website of the General Administration of Customs includes the Indonesian gar family. The reporter consulted Tianjin Customs and learned that this means that gar from Indonesia can be introduced into the country. In this list of admissions, the reporter did not find eels from other countries or regions.
"Now that alligator eels have been introduced, customs have begun to pay attention to them." Gu Dangen told reporters, "Some time ago, the relevant person in charge of the customs department found us and asked us to provide some pictures of invasive aquatic organisms such as crocodile eels, and then we should also strengthen management, indicating that all departments are taking action to prevent the invasion of alien species." ”
The Measures for the Administration of Invasive Alien Species, which came into effect on August 1 this year, stipulate that customs should strengthen the prevention and control of invasive alien species at ports and crack down on illegal acts such as illegal introduction, carrying, delivery and smuggling of alien species. Invasive alien species discovered and those assessed to pose a risk of invasion shall be disposed of in accordance with law.
"The Measures for the Management of Invasive Alien Species is the first management measure for the prevention and control of alien species in the mainland, which stipulates from the aspects of source prevention, monitoring and early warning, governance and restoration, etc., builds a whole chain prevention and control system, especially clarifies the functions of customs prevention and control and monitoring at ports, and helps to further enhance the efficiency of customs law enforcement at ports." Zhang Hongmei, director of the Animal and Plant Quarantine Department of Beijing Customs, said.
The Work Plan for Further Strengthening the Prevention and Control of Alien Species Invasion stipulates that the management of the introduction of alien species should be strengthened. It is clear: "Strictly approve the introduction of alien species in accordance with the law, strengthen the use control after introduction, and no unit or individual may introduce, release or discard alien species without approval." ”
It is understood that from January to June this year, Beijing Customs intercepted 280 batches of prohibited imports such as alien species from non-trade channels. "We have formulated and improved a series of prevention and control measures to prevent invasive alien species, strengthened port monitoring and census, continued to increase port prevention and control, severely cracked down on illegal acts, and effectively blocked illegal entry channels for alien species." Zhang Hongmei said. By the end of June, Beijing Customs and China Customs Science and Technology Research Center had completed the deployment of insect trapping points in the Beijing Customs Area.
On the other hand, the prevention and control of invasive alien species should also start from the grassroots level, Gu Dangen said.
Alligator eels are often discarded by farmers or released into the wild, causing harm.
"According to our observation, Brazilian turtles like Dinghu Mountain are basically sold to tourists, and tourists take them to release. But this is not a good deed, but a great harm. Li Zhenyu said, "Some elderly people have bought invasive alien species to release without knowing it, which needs to be publicized." ”
Article 38 of Chapter III of the Law of the People's Republic of China on the Protection of Wild Animals clearly stipulates that any organization or individual who releases wild animals into the wild environment shall select local species suitable for wild survival in the release site, and shall not interfere with the normal life and production of local residents to avoid causing harm to the ecosystem. Where wild animals are released arbitrarily, causing personal or property damage to others or endangering the ecosystem, legal responsibility is borne in accordance with law.
Li Li said that this regulation is very strict, so the behavior of indiscriminate release in the past one or two years has been curbed to a certain extent.
In addition to not buying and releasing them at will, grassroots people can also help find invasive alien species. According to Gu Dang'en's experience, among the people who found crocodile eels, there were more ordinary citizens.
The reporter previously consulted the Beijing fishery administration law enforcement personnel and learned that if the public sees someone releasing crocodile eels, they can report it to the fishery administration department.
Li Li also told reporters that if the public usually sees crocodile eels in the wild, it is best to fish them out and send them to the Aquatic Conservation Center or the local aquarium.
In addition, in the treatment of invasive alien species, Li Zhenyu believes that "the most clever way is to resource." "Some invasive alien animals actually have some economic uses, and it is necessary to find their value and use them.
For example, crayfish and bullfrogs are also invasive alien species, but they can be put on the table and open up an industry. According to Li Zhenyu, as an invasive alien species, the interfluille rice grass can also be used as food for elk.
But some invasive species cannot be recycled. Like the crocodile eel, Gu Dang'en said its economic value is very limited. It is understood that for the treatment of alligator eels, if the number is not large, it can be put into aquariums or related institutions as a propaganda use, generally as a negative teaching material for invasive species, to remind people not to release without authorization. If the number is large, it is generally killed and made into specimens or used for scientific research, or directly fished out and buried for harmless treatment.
Beijing News trainee reporter Ye Hongmei
Edited by Zhang Shujing Proofreader Wu Xingfa