1 Impact of overfishing on the environment
1. 1 marine ecosystem degradation
20 17 A news in September triggered people's comments-148000! Large yellow croaker with a length of more than 50 cm and a weight of 4.9 kg sells for a car price. However, it was recorded in Li Shizhen's Compendium of Materia Medica in the Ming Dynasty: "Stone fish can sing out of water" and "it comes from the ocean every April, and the sound is like thunder, which harms people to explore the bottom with bamboo tubes. When they hear its voice, they are cut off by the net. " According to statistics, the fishing output of Pseudosciaena crocea in China is 1974 tons, which is the highest in history, and then the output has decreased year by year. 1986 was only 17200 tons, only 8.7% of that of 12 years ago. In just twenty or thirty years, all the large yellow croaker in the East China Sea has been killed, which is amazing. Pseudosciaena crocea, with a very high yield in China, was once one of the "four major seafood" in the offshore of China. Now, things have changed and disappeared. The disappearance of large yellow croaker may put the whole marine ecosystem under the pressure of collapse. In 2003, the American magazine Science published an article saying that overfishing led to a sharp decline in the number of sharks in the Atlantic Ocean. In recent years, the number of jellyfish from the Yellow Sea to the Sea of Japan has greatly increased, and overfishing of marine fish is one of the reasons. The explosive growth of jellyfish will not only affect the changes of zooplankton population, but also affect the decrease of herbivorous copepods, leading to the occurrence of secondary blooms, which undoubtedly poses a major threat to the ecosystem. China Marine Development Report pointed out that long-term overfishing has led to serious degradation of marine fishery ecosystem, which is difficult to reverse. At present, 87% of the fish in the world are considered to be overexploited or completely exploited. According to the report of the United Nations Environment Programme 20 10, if the world continues to fish at the current rate, all fish may be extinct before 2050. According to literature statistics, about15 marine mammals in the world are on the verge of extinction. Due to the interlocking of food chain and food web, the number of a species is sharply reduced or even extinct, which will inevitably lead to the fracture of a link in the food chain where the species is located, which will inevitably lead to the survival threat of related organisms, and then lead to the sharp decline of marine biodiversity, and ultimately destroy the stability of the structure and function of marine ecosystems. From March 1 2065438, Guangxi will implement the most forbidden fishing system in the history of the Pearl River; Hezhou has the strictest "no fishing order", and illegal fishing can be punished; Before June 3 1, all fishing operations were banned on the Sanjiang River in Shaoguan ... a series of news reports, etc. It fully shows that the government has strengthened the control of fishing to protect the marine ecosystem. British marine biologist Paul said, "Big fish, including swordfish and catfish, are disappearing. If we don't stop it, we will see an ocean full of terrible little things, and no one wants to eat it. What we may end up with is a garbage dump full of plankton. "
1.2 Formation of "Marine Garbage Belt"
In the process of fishing, a lot of garbage will inevitably be produced, and most of the garbage will be discharged into the ocean. Marine plastic waste produced by marine fishery activities has become one of the important factors that destroy the environment. According to a statistic published in Nature-Communication, a sub-issue of Nature magazine, there are115-2410000 tons of plastic waste discharged into the sea through rivers every year in the world, and Asia accounts for 67% of the total global pollution. Most of the 20 most polluted rivers are located in Asia, and more than 90% of marine plastic waste comes from the most polluted 122 rivers, among which 103 is also located in Asia. Affected by the East Asian monsoon, from May to 10 every year, 74% of the garbage enters the sea through rivers. According to the British "Mirror" reported on March 6, Richard, a 45-year-old former mechanical design engineer in Britain? Horner found that the water was full of bottles, wrapping paper and bags when he was swimming near the beautiful coast of Menglan Island in Indonesia. Bali used to be picturesque, but now it is so seriously polluted by seawater.
2. Impact of offshore aquaculture on the environment
2. 1 Eutrophication of water resources and frequent marine disasters
The residual bait and excrement produced by offshore aquaculture enter the water body, and the N, P nutrients, suspended particulate matter and organic matter contained in the residual bait and excrement will become the pollution source of water eutrophication. Eutrophication of water body accelerates the growth of algae, forms a suitable environment, and provides cheap conditions for disasters such as red tide and water bloom. Take the red tide as an example. From 2008 to 20 12, there were 66.6 red tide disasters every year, and the red tide disaster area was about 10556km2.
2.2 Biodiversity and destruction of coastal ecosystems
Offshore aquaculture has a great impact on the ecosystem, and shrimp culture has a significant impact on mangroves. However, mangroves play a very important buffering role in the process of mainland-coastal water exchange. For example, after the mangrove forest in Futian, Shenzhen is destroyed, the species and number of birds that inhabit for food will be reduced, and the balance of mangrove wetland ecosystem will also be destroyed. Pests, especially LEPIDOPTERA insects, lack natural enemies, and pests occur in large numbers, even reducing the pH value of water, which has toxic effects on most aquatic organisms and leads to many environmental changes. It can be seen that the influence of unreasonable marine fishery activities not only leads to the decline of marine biodiversity and the destruction of habitats, but also directly or indirectly affects the stability of terrestrial ecosystems. The scientific evidence is irrefutable: the earth's climate is changing, and strange things are happening all over the earth-coral reef deaths, large-scale mudslides, unusual rainstorms, and persistent droughts in some areas ... It can be said that marine ecosystems participate in the material circulation and energy flow of the entire biosphere and play an important role in the global climate, water bodies and environment.
3 Conclusion
With the improvement of people's living standards, the demand for seafood is increasing, and marine fishery has also developed rapidly, which is called an important part of China's economy. However, while blindly pursuing economic benefits, it ignores the sustainable development of marine economy, which has caused serious impact on the environment. A series of environmental problems, such as degradation of marine ecosystem, flooding of marine garbage, serious eutrophication of water bodies, frequent marine disasters, decline of biodiversity and destruction of coastal ecosystems, have become increasingly prominent. If we take into account the sustainable development of marine economy while reaping economic benefits, I believe that China's marine economy will make a qualitative leap.