The prospect of aquaculture in the future ten years

Introduction: aquaculture production has increased by 11% every year in the past decade, which is the fastest growing part of the world's food economy From 13 million tons in 1990 to 31 million tons in 1998, aquaculture as a source of food has surpassed animal husbandry at the end of the century In the last century, the world relied on two natural systems: the ocean and the pasture to meet people's needs for animal protein This era has come to an end, because both systems have reached the limits of their production In the 40 years from 1950 to 1990, four fifths of beef production came from pastures, from 19 million tons to 53 million tons, almost tripling The major beef consumers are Argentina (69 kg per year), the United States (45 kg), Brazil (39 kg) and Australia (36 kg) At the same time, ocean capture increased from 19 million tons to 86 million tons, more than quadrupling But after 1990, neither has grown much The extra production of meat and aquatic products depends on captivity and pond culture The efficiency with which cattle, sheep and fish turn food into protein begins to affect production and our diets One kilogram of cattle needs seven kilograms of grain, while one kilogram of fish needs less than two kilograms of grain Water shortage is also a concern, because 1000 tons of water can produce 1 ton of grain In a world with less water and less land, fish ponds have obvious advantages over cattle pens in producing low-cost protein Meat production is concentrated in industrialized countries, with about 85% of aquaculture in developing countries China has a history of fish farming for more than 3000 years In 1998, it produced 21 million tons of aquatic products, accounting for 67.7% of the world's aquaculture production India, the second largest producer, produced only 2 million tons In industrialized countries, Japan, the United States and Norway are major aquaculture countries Japan produces 800000 tons of high-value varieties such as sea fans, oysters and yellowtail grouper The 450000 tons of aquatic products produced in the United States are mainly catfish The 400000 tons of aquatic products produced in Norway are mainly salmon Now that the oceans are overfished, developing countries are turning to aquaculture to meet the growing demand for seafood Due to the pressure of population, only a small amount of rice is planted in Japan, and it turns to the ocean for animal protein source Today, 125 million people in Japan consume 10 million tons of seafood a year If China, with a population ten times that of Japan, eats seafood like the Japanese, it needs 100 million tons of seafood, which is equal to the global catch There are more than 220 kinds of fish, shrimp and shellfish in commercial culture, only a dozen of which are the main varieties of world production In 1998, there were 11 million tons of five species of Cyprinidae (widely cultivated in China), accounting for one third of the world's total aquaculture output There are 3.4 million tons of oysters in the Middle Pacific Ocean, followed by scallops and mussels China keeps fish in ponds, lakes, reservoirs and rice fields There are 5 million hectares of land devoted to fish farming, mainly for multi species mixed farming, and 1.7 million hectares of rice fields for fish farming For thousands of years, we have developed the technology of mixed cultivation of four big fishes They are fed at different levels of the food chain Silver carp and bighead carp are filter fed They eat plankton Grass carp mainly eat grass The bottom carp eat organic debris at the bottom of the pool Most of China's aquaculture is integrated with agriculture, which can use agricultural wastes such as pig manure and water to promote the growth of plankton The yield of mixed culture is generally more than half of that of single culture, and so is that of India Due to the lack of land and water resources, aquaculture farmers in China rely on increasing food supply to improve the productivity of ponds The input per hectare increased from 2.4 tons in 1990 to 4.1 tons in 1996 In the United States, catfish, the dominant breed of aquaculture, needs 1.6kg of feed to grow 1kg of meat Last year's catfish production was about 270000 tons, more than 2 pounds per person American catfish consumption exceeded that of mutton American catfish production is concentrated in four states: Mississippi, Louisiana, Alabama and Arkansas Mississippi has 45000 hectares of catfish ponds, and 60% of the catfish production in the United States is exported, which is the largest catfish product in the world There are two kinds of aquatic products that cause far-reaching environmental disasters: Sanmen fish (annual output of 700000 tons) and shrimp (annual output of 1.1 million tons) Most of them are farmed and produced in industrial countries, mainly Norway for consumption in European countries Shrimp farming is mostly in developing countries, important countries are Thailand, Ecuador and Indonesia, export to rich society Sanmen fish is a carnivorous fish The feed includes fish meal, which is typically made by anchovy, herring and fish processing plants The production of herbivorous species such as Cyprinids and catfish has greatly reduced the pressure on the marine fishery In contrast, the cultivation of Sanmen fish has actually increased this pressure, because it takes 5 tons of marine products to raise 1 ton of Sanmen fish In addition, one of the concerns is that the purpose of rapid growth is not to release the farmed three door fish Because the storm or animals such as seals escape from the enclosure, they can breed together with the wild three door fish, thus weakening the survival ability of the wild population The three door fish growing in the coastal cage or enclosure also discharge a large amount of waste, which is an urgent problem to be solved For example, the waste generated by three fish farmed in Norway is equal to the domestic sewage discharged by 4 million Norwegians Shrimp culture is often carried out after clearing the coastal mangroves, which protect the coastline and the cradle of nearby fish The destruction of mangroves will cause the decline of local fisheries, which is not worth the loss In addition, prawn feed also contains a lot of fish meal Prawn culture and three door fish culture increase the pressure of marine fishery The world is facing the production limit of Marine Fisheries and pastures The annual growth of 80 million people needs to produce more animal protein What is the most effective way? Herbivorous fish species such as carps in mixed culture, catfish in paddy field or catfish in pond provide an efficient way to expand animal protein supply in the hungry world Fish farming is not the only way to solve the world's food problem, but as China has shown, it provides low-cost sources of animal protein for low-income people The country with the fastest aquaculture development in the past decade may also be the country with the fastest development in the next decade.