Why is an insecticidal pesticide a "killer" for fish
Produced by Deep Eye Studio
Written by: Intern reporter Dai Xiaopei Planning: Liu Li
Drugs will be developed for new uses, and the drugs themselves will be updated faster and faster, which will increase the difficulty of drug management. If drug control cannot be updated in time according to actual needs, it is easy to leave a loophole for drug abuse behavior.
Rollover, swimming wildly, convulsions, lying still underwater due to loss of balance, and then waiting for death.
This is a typical symptom after fish nerve poisoning.
In March of Yangchun, it was the time for all things to recover. In Mazui Lake, Jinxian County, Nanchang, Jiangxi, a large number of fish died of nerve poisoning.
Dead fish floating on the lake, some were salvaged and thrown into wooden boats, some were picked up by local villagers.
Jinxian County is surrounded by water on three sides, Poyang Lake in the north, Qinglan Lake in the west, and Junshan Lake in the east.
The originally connected Mazu Lake and Qinglan Lake were separated by a levee.
On March 16, the Jinxian County Agriculture and Rural Bureau issued an investigation report stating that the dead fish incident occurred at the Mazui Lake Ecological Gorgon Water Planting Base, which was contracted by a company.
In order to kill, the company sprayed fenpropathrin in the gorgon planting area.
It was this move that caused the accidental death of a large number of fish.
Fenpropathrin, also known as "Miesauli", is a pyrethroid pesticide, which is a neuropesticide.
The precautions for this product point out that it is very toxic to fish and shellfish, and it is strictly forbidden to pour the water from the washing container or the remaining liquid medicine into rivers or ponds.
But the reality is that fenpropathrin is often thrown into the waters intentionally or unintentionally, causing fish and other aquatic animals to be destroyed.
In mid-March, the Ministry of Agriculture and Rural Affairs launched a special rectification action, requiring all localities to carry out a carpet investigation of illegal use of pesticides to poison fish and shrimp in sea cucumber farming. One of the particularly strict investigations is the illegal use of fenpropathrin.
New use of old medicine, insecticidal pesticides repeatedly kill fish
The use of medicines sometimes inadvertently deviates from the track pre-designed by its inventor.
Nobel invented explosives, hoping to reduce the work intensity of workers in rock drilling, but explosives were later widely used in warfare; Li Dejun developed "paraquat" to reduce the burden of weeding by farmers, but "paraquat" was swallowed by many suicides, resulting in drugs Eventually it was disabled.
It seems hardly surprising that a similar "misuse" occurs with fenpropathrin.
Fenpropathrin products are mostly creamy. After adding water and blending, spray on the crops by spraying. It can kill cabbage worms on cabbage, red spiders on apple trees, cotton bollworms on cotton, etc. It can also cure mites. .
Fenpropathrin knocks down pests quickly, with high efficiency, broad spectrum, and low residue. For this reason, it is widely used in agricultural production.
However, after fenpropathrin enters the water, it can directly enter the gills and blood of the fish, causing the fish to have difficulty breathing and metabolic disorders.
Some researchers have found that fenpropathrin is more toxic to zebrafish, eels, crayfish, river crabs, loach, etc. Generally, a concentration of less than 0.001 g/l can produce toxic effects.
Due to its strong toxicity to fish and other aquatic animals, fenpropathrin should be kept away from the water, but it is thrown into the water from time to time to become a fish "killer".
In April 2014, Xu Mou, a fisherman in Mingguang City, Anhui Province, used 600 bottles of fenpropathrin (250 grams per bottle) to poison fish in a polder area of 1,200 acres of water, killing herring, grass carp and other big and small fish on the spot by about 3,000 catties, which was serious. Polluting the water environment and destroying fishery resources.
In August 2017, Wang Mou in Danyang City, Jiangsu Province poured the cleaning agent he bought online into the fish pond, which caused a large number of fish in the fish pond to die. After identification, the water in the fish pond and the suspected pond cleaning agent were sent for inspection Fenpropathrin components were detected in all bottles.
In the precautions for fenpropathrin products, it is clearly marked "it is strictly prohibited to pour the water from the washing container and the remaining liquid medicine into rivers or ponds".
However, when a reporter searched for "fenpropathrin" on an e-commerce platform, they found that most of the advertisements for fenpropathrin products contained the words "cleaning pond" and "clearing pond".
When the reporter asked a pesticide seller about the "pond cleaning agent", the other party replied: "I heard that fenpropathrin can clean the pond." Some buyers also said that the purpose of buying fenpropathrin is to kill wild trash fish.
Some people even think that fenpropathrin is not an insecticide, it is specifically used to clear ponds and kill fish.
In aquaculture, clearing the pond is a basic task.
Through clearing the pond, harmful wild trash fish, parasites, pathogens and some aquatic insects that affect production can be killed, providing a good environment for aquatic products.
"In recent years, the application of pyrethroid pesticides in Qingtang and other aquaculture links has occurred." Wang Guangjun, a researcher at the Pearl River Fisheries Research Institute of the Chinese Academy of Fishery Sciences, said frankly. The ester is put into the water as a pond clearing agent."
According to the investigation report of Jinxian County, the above-mentioned companies put fenpropathrin in Mazui Lake to remove some pests on the gorgon in spring, that is, it is used as a pond clearing agent.
Wang Guangjun said: “For fish farmers, the more fish, the better. But for people who keep aquatic plants, shrimp and crabs, wild trash fish may be a kind of'harm'. Gorgon seedlings are tender and easy to be wild. Trash fish are eaten, and fenpropathrin is more effective in killing insects and wild trash fish, so it will be used as a pond clearing agent."
Yang Lihua, an associate researcher at the Institute of Hydrobiology, Chinese Academy of Sciences, said: "Similar'old medicines with new uses' are not uncommon."
However, fenpropathrin is a pesticide. According to Article 35 and Article 60 of my country's "Pesticide Management Regulations", the use of pesticides to poison fish, shrimp, birds, and animals is strictly prohibited.
The drugs used in aquaculture shall comply with national and local regulations and standards on the safe use of pesticides and fishery drugs.
"However, there is currently no better drug on the market that can replace fenpropathrin as a pond clearing agent, or other drugs are not as effective as fenpropathrin in killing wild fish. In this case, some farmers are legally aware If you are weak, you will risk using fenpropathrin to clear the pond." Wang Guangjun said.
Bio-enriched pesticides, and finally passed into the human body through the food chain
Generally speaking, farmers usually need to put specific chemicals in the breeding environment to ensure that the breeding environment is beneficial to aquatic products.
However, the unreasonable usage and dosage control of drugs will directly pollute the breeding environment.
What are the hazards after pesticides are put into waters?
Experts say that long-term excessive and unreasonable use of pesticides can easily cause a large amount of pesticides to migrate from the soil to the breeding environment or fishing waters.
Sun Huili, a researcher at the South China Sea Institute of Oceanology, Chinese Academy of Sciences, pointed out that excessive use of pesticides has aggravated the problems of water pollution and chemical pollution of aquatic products.
"Due to the effect of bioconcentration, organisms will accumulate certain elements or hard-to-decompose compounds from the surrounding environment, so that the concentration of the substance in the organism exceeds the concentration of the substance in the environment, which will endanger the safety of the organism." Nanjing University of Traditional Chinese Medicine College professor Wu Qinan said that the illegal use of pesticides will have a negative impact on the safety of aquatic products.
Yang Lihua said that humans are at the top of the food chain, and pesticides enriched in aquatic organisms may eventually pass through the food chain and enter the human body.
The "Aquaculture Drugs Understanding Paper No. 1, 2020" issued by the Fisheries and Fisheries Administration of the Ministry of Agriculture and Rural Affairs clearly pointed out that there should be "six non-uses" in the standardized use of aquaculture drugs: no banned drugs, no discontinuation of veterinary drugs, no fake or inferior drugs. Veterinary drugs do not use raw materials, human drugs, and pesticides.
Existing studies have shown that not only pesticides, but also fishery drugs specifically used in aquaculture should not be used in excess.
According to the "Notice on Strengthening the Supervision of Inputs for Aquaculture" by the Ministry of Agriculture and Rural Affairs, inputs for aquaculture should be managed in accordance with veterinary drugs, feed and feed additives, regardless of the name of "xx agent", the corresponding should be obtained according to law. The production license and product approval document number can be used for production, operation and use.
However, the farmers put the pesticide fenpropathrin into the water for the purpose of clearing the pond. This is a measure of self-protection in a sense. Can it be legally understood?
"Although this is for self-protection, it has an impact on the public environment." said Professor Yang Zhaoxia, director of the Ecological Law Research Center of Beijing Forestry University. "Waters have different attributes and functions. Even waters that are privately contracted are still important. The public attributes of the ecological environment elements still exist."
Yang Zhaoxia analyzed that the protection of personal interests cannot be established on the basis of harming the interests of others and the public interest.
"Although the use of fenpropathrin to clear the pond is subjectively only for the purpose of clearing the pond, it objectively damages the fishery resources and the ecological environment of the water area and cannot escape legal responsibility."
He also added: “The use of pesticides to poison a large number of fish has caused ecological damage. According to the Civil Code, the parties must also be liable for damages to the ecological environment. We are people in society as well as people in the natural system. When exercising rights and carrying out relevant activities, the impact on the ecological environment must be considered."
"The use of pesticides in order to ensure the environment for aquatic production and breeding has caused a large number of fish to be poisoned. There has not been much attention to such cases before." Yang Zhaoxia said frankly, "Such cases remind us not only to prevent subjective illegal fishing. The behavior of fishery resources should also prevent bad behaviors that are subjectively innocent but objectively cause damage to fishery resources and public waters."
In fact, with regard to aquaculture, the Ministry of Agriculture of my country has published a list of prohibited fishery drugs and a list of commonly used fishery drugs.
Fenpropathrin is a pesticide and is neither on the blacklist of prohibited fishery drugs nor on the red list of permitted fishery drugs.
Yang Lihua said: “Drugs will be developed for new uses, and the drugs themselves will be updated faster and faster. This has increased the difficulty of drug management. If drug control cannot be updated in time according to actual needs, it will be easy to leave the behavior of drug abuse. A chance to take advantage of the loopholes."
She suggested that the relevant regulations on drug control should be updated in time, the supervision of new drugs should be strengthened, the purpose, usage, and dosage of drugs should be clarified, and dynamic adjustments should be made according to the actual use of drugs.
What worries Yang Zhaoxia is that when talking about the unreasonable use of pesticides, we should not only focus on the public interest, but ignore the legitimate private interests of aquaculture farmers.
"We cannot seek development at the cost of destroying the environment. This is the basic principle."
Yang Zhaoxia believes that it is necessary to balance the interests of aquaculture and the ecological environment.
In this regard, Liu Wanxue, a researcher at the Heilongjiang Provincial Aquatic Technology Extension Station, and others called for aquaculture drug reduction action. They believe that this can not only reduce the production cost of aquaculture, increase the economic benefits of aquaculture, but also improve the quality of aquatic products and protect ecological safety.
Wang Guangjun suggested the research and development of some low-toxicity, high-efficiency, no "three causes" and no residues that are green and environmentally friendly and pollution-free alternative medicines.
"Aquaculture farmers have poor ability to resist risks. In the event of some major diseases, they may use banned drugs when there is no other way. For example, malachite green has been explicitly banned, but farmers will still encounter water mold. Take the risk of using the forbidden drug of malachite green." Wang Guangjun said.
In the prevention, control and treatment of diseases and pests of aquatic animals and plants, fishery drugs play an important role, which can promote the healthy growth of aquaculture species, enhance the body's disease resistance, and improve the quality of aquaculture water.
Ye Yiwen, a fisherman from the Fishery Supervision Detachment of Luoma Lake, Jiangsu Province, said that green fishery drugs should be developed and used in a standardized manner.
Common green fishery medicines have significant effects on preventing and controlling aquatic diseases, and they will not cause harm to the water environment.
Some aquaculture water products that are not fishery medicines but have fishery medicine functions are also called green fishery medicines, such as quicklime, tea seed cake, allicin, salt and so on.
"Quicklime and tea seed cake have a very good effect on clearing ponds, and they are also friendly to the environment." Wang Guangjun said.
It should be noted that quicklime can not be used to clear ponds in water bodies with strong alkalinity.
Since 2012, Wu Qinan has often conducted research in some Gorgon planting bases in Gaoyou and Huai'an, Jiangsu, observed the planting process of aquatic medicinal plants in the field, and conducted related research to assess the safety of the planting environment of aquatic plants by establishing a risk warning model .
Summarizing years of experience, Wu Qinan believes that the quality and safety of aquatic products and the safety of the ecological environment are prerequisites that must be considered in the research and development of fishery drugs.
Chemical drugs and antibiotics that are toxic and have residues that do not meet the quality requirements of aquatic products should be gradually restricted or banned.
The Ministry of Agriculture and Rural Affairs proposed in the special rectification action of related pesticides that it is necessary to mobilize personnel from aquatic technology promotion, scientific research, teaching and other institutions to provide technical guidance for farmers in the removal of algae and predators, and specifically warn them not to use pesticides or use the so-called " Unapproved inputs such as "non-pharmaceuticals" and "water quality improvers" have continuously improved awareness of standardized production and drug use.
Experts also suggest that online sales of pesticides have become more common, and it is recommended to strengthen management of pesticide sales on e-commerce platforms.
For example, sellers are forbidden to indicate that fenpropathrin can be used as a pond clearing agent in advertisements to avoid misleading consumers.
Ecological breeding technology also provides a possible solution for balancing aquaculture and environmental protection.
"The'rice-crab symbiosis' model in Panjin, Liaoning, the'shrimp and rice co-cultivation with rice, fishery and rearing' model in Hubei, the'fish and vegetable symbiosis' model in Chongqing, and the symbiosis model of fish (shrimp) and lotus root in some places. Farming technology can not only increase the income of farmers, but also purify water quality." Wang Guangjun said that similar ecological models can be further explored and promoted in aquaculture.
"In the past, we paid more attention to the output of aquatic products, and in the future, we will pay more attention to the quality of aquatic products and the protection and improvement of the ecological environment. With the increasing responsibility for environmental protection, in aquaculture, technical research to promote the harmonious symbiosis of ecological elements is required. Further strengthen." Wang Guangjun believes, "To some extent, ecological planting and breeding can solve some problems of unreasonable use of pesticides and protect the ecological environment."
"We cannot seek development at the cost of destroying the ecological environment. This is the basic principle." Wu Qinan said.