When it comes to farms and pastures, people will definitely think of green farms full of various crops-grain, oil, cotton and sugar, and pastures where cattle and sheep are grazing on the grass. Primitive people made a living by fishing and hunting. They hunted wild animals with bows and spears on land and caught fish and shrimp with nets in the water. Later, people learned to domesticate cattle, sheep, pigs, chickens and other animals, so there was a pasture. Later, I learned to grow food and cash crops, so I had a farm. There are abundant aquatic resources in the ocean. Capturing natural animals and collecting natural seaweed can barely meet people's needs, but the need to establish offshore farms is not so urgent. In addition, the marine environment is far worse than land, and it is difficult to develop artificial farming in rough waters, so the main force of marine fishery is fishing.
Zeng Chengkui, a famous marine biologist in China, put forward the concepts of marine farm and pasture, and advocated turning the blue land into a farm for planting marine plants and a pasture for breeding marine animals. He took the lead in cultivating seaweed and laver seedlings in China, and studied the artificial propagation methods of seaweeds and laver. Kelp and laver are both large brown algae, which are marine vegetables and rich in iodine and calcium. In shallow water, the structure attached to kelp and laver floats by plastic floating balls, so that these algae can live in the transparent layer, fully carry out photosynthesis, and can also apply chemical fertilizer. In the past, the barren sea surface became farmland for growing seaweed. Algae such as Undaria pinnatifida and macroalgae can also be planted in a similar way.
Macroalgae can be planted and micro algae can be raised. Spirulina is a very small algae, but it has amazing ability to produce protein, and its reproduction speed is very fast. In Guangdong, Hainan and other subtropical and tropical coastal areas, ponds are built to attract seawater to raise spirulina, and the yield is very high. Some people even imagine that spirulina will become the main food on the table in the future, which may be exaggerated. At present, spirulina is only mixed with bread and biscuits to add nutrients such as protein, and most products are used as bait to feed aquatic products such as fish and shrimp.
There is a blue-green algae that grows on the bottom of the sea. It breeds quickly and grows luxuriantly, and can form a dense waterproof layer on the seabed. Planting cyanobacteria in the salt pond of Yantian can also prevent the salt pond from seepage.
Artemia can also be raised in Yantian. Artemia, also called harvest worm, is a small crustacean and a distant relative of shrimp. This animal is rich in carotene, which can not only be used as feed for marine cultured animals, but also be extracted from it as functional food and medicine.
Spartina is a kind of nutritious feed, which can be planted on the beach by the sea.
Giant seaweed along the coast
Giant algae grow very fast and are planted in the sea in large quantities. After harvest, it can be used as fuel to generate electricity, which is a promising renewable energy source.
In addition to breeding prawns by releasing them, shrimp ponds can also be built on the seashore to attract mariculture. In 1980s, there were many people who raised shrimps and became rich in the coastal areas of China, and a large number of shrimps were exported. Seedling raising, disease prevention and fattening are the key technologies of shrimp culture. But later, more people raised prawns, and the density of prawns in the shrimp pond was so high that the water in the pond was overnourished, and even the coastal seawater was polluted. Sometimes, a large number of algae grow, and the oxygen in seawater is consumed, which leads to the "red tide" disaster. When the sea water is polluted, shrimp is easy to get sick and die. In recent years, scientists have developed some methods to prevent and treat prawn diseases, but they have not been completely solved. Since 1990s, shrimp culture in China has been hit hard by a large number of deaths in some shrimp ponds.
Artificial shrimp farm
In addition to prawns, Penaeus monodon, Macrobrachium rosenbergii, South American white shrimp and lobster can also be raised, which has stronger disease resistance than prawns.
After the artificial culture of crabs is solved, they can be cultured in ponds or artificial reefs by the sea.
Shellfish has a small range of activities and is most suitable for farming, and does not need a lot of bait. Shellfish culture in China has developed rapidly. Scallops are now the most widely cultivated. The adductor muscles of scallops are very developed and delicious. Before artificial breeding, scallops dried with the adductor muscle of scallops are very precious seafood. In 1980s, China introduced several new scallop varieties from abroad and developed breeding methods. In the past ten years, it has been widely planted in coastal areas. Scallops are kept in cages, which float on the sea. Scallops feed on plankton in the sea and grow up in cages. After a while, put the cage away, remove algae and other marine animals parasitic on shells, and put them in the sea, and you can harvest them in a short time. Abalone is not a fish, but a shellfish and a rare seafood. Its shell is called concha Haliotidis, which is a traditional Chinese medicine. It lives on rocks, and now it has found a way to raise seedlings and put them in a sea pool by the sea. Sea cucumbers and sea urchins have also begun to be stocked in sea pools, and they have gained a lot. Mussels can be raised in bellows. Oyster culture has a long history and can be cultivated on bamboo chips inserted in the beach or bamboo rafts floating on the sea. Shellfish such as clams, clams and bees should be kept on the beach. When the pearl shell enters foreign bodies such as sand, it will secrete liquid to wrap the foreign bodies, and over time it will form dazzling pearls. Hepu, Guangxi, is famous for producing "Nanzhu" in history. In China, shellfish breeding and pearl picking have now developed into an industry.
It is more difficult to raise fish than shellfish. Fish need more room to move. They can't just eat plankton in seawater. They need to constantly put in bait, and the problem of fry is not easy to solve. Many kinds of fish live in the sea and lay eggs in brackish water at the mouth of the river when they grow up, such as mullet (barracuda); Some fish lay eggs in the ocean, while young fish are concentrated in estuaries, and adult fish live in fresh water, just like eels. Therefore, raising eels requires fishing eel fry from the estuary where young fish are concentrated. Raise fish artificially, but also domesticate them, so that they can adapt to the life in cages or fish ponds and grow up. At present, mullet, perch, grouper, snapper, whitebait, eel, flounder, salmon and tilapia have been able to migrate to the environment arranged for them to grow. Cultivating the habit of fish eating plankton directly can reduce the cost of farming. Now, many kinds of feed organisms have been developed, such as spirulina and Artemia, which are delicious and nutritious food for fish. Plankton used as fish feed has to be cultivated artificially on a large scale, otherwise it is not only too expensive to catch plankton in the sea, but also difficult to meet the needs.
Kelp farm
In the development of farms and pastures, the ocean has incomparable advantages over land. Only the surface layer of land can be used, while seawater can be used in layers on the ocean. Together with the bottom of the sea, it becomes a three-dimensional marine farm and pasture. Mixed culture of fish, shrimp, shellfish and algae is much better than simply raising a kind of aquatic products, which can not only create a suitable local ecological environment, but also make full use of nutrients, because some varieties of waste just happen to be other people's food. Fishermen in Shandong and Liaoning raise a variety of aquatic products at the same time: the upper layer is transparent and suitable for raising algae such as kelp and laver; Scallop culture in middle cage; Fish culture in the lower layer; Sea cucumber, sea urchin, crab, etc. Raised at the bottom. Proper collocation can not only save the sea surface, reduce investment, but also prevent biological diseases, create a cleaner environment, and increase the output of various products. It's killing two birds with one stone!
sea cucumber
Marine farms and pastures must maintain a good environment. Scientific instruments should be used to monitor the temperature, salinity, pH value, dissolved oxygen and biological oxygen consumption of seawater in farms, and manual control should be carried out to ventilate and change water in time to prevent polluted seawater from leaking to farms and pastures.
For aquatic products in marine farms and pastures, a variety of vaccines, antibiotics and hormone drugs have been developed to deal with viruses and bacteria. Fish interferon is an effective drug to treat fish diseases, and ultrasonic wave can enhance the immune function of fish.
From the low-value algae cultivation in 1950s to the all-round development of fish, shrimp, shellfish and algae and the key cultivation of marine treasures, the output value of aquaculture in China has ranked first in the world. Two island counties, Changhai in Liaoning and Changdao in Shandong, have become the richest counties in China by aquaculture. Shandong province put forward the slogan of building "Shandong on the sea" and vigorously developed aquaculture. China has 370,000 square kilometers of shallow sea area, 20,000 square kilometers of intertidal beaches and 1.3 million square kilometers of beaches. If all the sea areas suitable for aquaculture are developed into Fulan farms, how many protein can be provided!
Protein in marine organisms is of high quality and easily absorbed by the stomach, which is necessary for human development and has the function of strengthening brain cells. Seafood is low in cholesterol, rich in iodine, easily absorbed calcium and various vitamins, especially vitamins A and D. In short, seafood is not only delicious, but also nutritious, and is an ideal food for human beings.