Research report on aquaculture

Abstract: The polyculture of Asparagus and oysters and the polyculture of shrimps and crabs are the prevailing mode of farming in South Australia, which has brought huge economic benefits to South Australia. After the polyculture of Asparagus and Pacific oysters, no serious red tide occurred in the area. . Our team conducted a field study on this, interviewed the farmers and recorded the mixed breeding process of the asparagus and oysters, so that we really learned the farming knowledge. These two models have great significance for farmers in the local and other regions. This paper reviews the breeding methods of these two models and discusses their effects on ecological balance. The survey found that the promotion of this model has its irreplaceable value both in terms of economic benefits and marine ecological protection.

Keyword polyculture benefit ecological balance

1. Research background

Shantou Nan'ao County is the only island county in Guangdong Province. It is located at the eastern end of Guangdong Province, at the junction of the South China Sea and the Taiwan Strait. There are 35 islands with a total area of ​​108.57 square kilometers, of which the main island Nanao Island covers an area of ​​106.14 square kilometers and the coastline is 76.77 kilometers. With a population of 72,000, marine fishery is still the main industry. The county has a sea area of ​​4,600 square kilometers, and the marine fishing industry is developed. It is one of the top 100 counties in the country. The island's aquaculture industry is also very prosperous, mainly breeding shrimp, crab, abalone and other seafood. During the investigation, we were pleasantly surprised to find that the pattern of polyps and oysters mixed with polyps and shrimps and crabs was very popular in the local area, and according to the farmers, the results were very good. Therefore, we have focused on this discussion and research.

Asparagus is native to the province of Shandong Province and Okinawa, Japan. It is not only a high-quality raw material for extracting agar, but also a rare marine vegetable for human green health food, or an excellent feed for marine animals such as abalone. The cultivation of asparagus also has its unique function to purify the sea environment and reduce the occurrence of red tide. It has high edible, medicinal and economic value and produces good ecological effects. From 1999 to XX, the Institute of Oceanology of the Chinese Academy of Sciences, the Guangdong Ocean Resources Research and Development Center and the Science and Technology Xinghai Office of Nan'ao County cooperated to carry out the project “Research on the migration of E. sinensis to the southeastern Australian sea area of ​​the Yangtze River”. The results have reached the scale of production.

Pacific oyster is native to Japan and Australia. It is a famous and economical shellfish with rich nutrition and fleshy taste. It is known as the “Marine Milk Boutique”. South Australia has excellent natural conditions and the development of Pacific oysters has a unique advantage. As early as 1984, South Australia introduced the Pacific oysters for hanging test, which was successful in one fell swoop and has been promoted as a conventional variety.

According to reports, in South Australia Island, local fishermen try to “interleave” polyculture of Asparagus and Pacific oysters, which not only increases the income-generating opportunities for fishermen, but also builds a giant sewage treatment plant in the sea to effectively purify seawater. Pollution [1]. A red tide occurred in Shantou in 1998, but since the introduction of the asparagus in 1999, there has been no red tide in the nearby waters.

Shrimp and crab polyculture is a set of farming methods that island fishermen have figured out in recent years. It is suitable for many areas. Because of its obvious effect, it has been promoted. Almost every farmer adopts this model. There are already patterns of lobster and crab mixed in all parts of the country. It is said that the lobster production in this way is 10 percentage points higher than the lobster production alone, and the lobster is relatively large and healthy. Crabs are relatively large in size, and mature time will be one or two weeks earlier. There are also patterns of polyculture of fish and shrimp. This model has obvious benefits and is particularly prevalent in the middle and lower reaches of the Yangtze River. Its advantage is that the fish can feed on the excrement of the shrimp, which not only reduces the feed, but also keeps the pond water quality better, which is beneficial to the shrimp culture, because the water quality requirement during the growth of the shrimp is much higher than that of the feed. Claim. In addition, there are breeding methods in which fish, ducks and rice coexist, but only in places with sufficient water in the south, the feces of fish and ducks are not only the best nourishment of rice, but also greatly reduce the occurrence of pests and diseases. Formed a partial ecological balance model.

2. Survey activity overview

Researcher: School of Chemistry and Environment, South China Normal University, Santuo Township Social Practice Service Team, Nanao Island, Shantou

Research time: July 15, 2019 to July 22, 2019

Research location: Xishan Village Road Section of Houzhai Town, Yangyu Village Farm of Houzhai Town, and offshore culture area of ​​Yangyu Village

3. Introduction to research methods

Our research team used the form of interviews to interview farmers through field visits to understand the current development of the South Australian aquaculture industry.

In this interview, our research team paid special attention to the details, especially during the interview process, paying attention to the communication and interaction with the farmers. Also, special attention is paid to some of the particularly subtle farming experiences mentioned by farmers, many of which are the secrets to their success.

During the interview, we recorded our research process through photography and video recording, which increased the credibility and persuasiveness of our research results. In particular, I am very grateful to the farmer who has been farming in the sea. I specially drove us to go out to sea to film his oyster farming methods and processes.

Despite the many problems encountered during the investigation, for example, the weather is hot, some farming areas are sparsely populated, and farmers are refusing to be interviewed... but every time our research team members can persist, and the research methods can be adjusted in time, combined with the local The specific situation is to develop a set of research plans that are appropriate for it. The head of our research team will also hold regular seminars and summarize the results of the survey in a timely manner.

4. Research results

4.1 Polyculture mode of Asparagus and oysters [2]

4.1.1 Cultivation mode of Asparagus

4.1.1.1 筏式单养龙菜. This is the main form of cultivation, most of which are 3 龙 龙 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续 连续

4.1.1.2 Asparagus and kelp round rotation. Asparagus is cultivated from September to December, and kelp is cultivated in December-April, and asparagus is cultivated from April to July. A few are cultivated asparagus from July to September.

4.1.1.3 Asparagus and oyster-style rotation. In the summer, autumn and winter seasons, pleated oysters are hoisted, and after winter and spring oysters are harvested, Asparagus is cultivated 1茬--2茬.

4.1.2 Cultivation techniques of Asparagus

4.1.2.1 Sea area selection. 1 Substrate: except for the rugged rock reef bottom. 2 water depth: water depth of 2.0m or more under the large dry tide line in winter. 3 Wind waves and water currents: At present, due to the strong cultivation equipment and strong wind and wave resistance, it can be cultured in the sea areas with more tidal currents, and the sea areas with less wind and waves require smooth flow. 4 Water quality: The water quality in the southern sea area is generally fertile. As long as the proportion of seawater in the sea area during the breeding season is above 1.018, there is no serious pollution of industrial wastewater.

4.1.2.2 Sea area layout. The requirements are arranged in a "good" shape.

4.1.2.3 Truss setting

Positioning piling. Since the production of asparagus in the south is to avoid the typhoon period in the hot season, the main factor in considering the direction is the trend, and the direction should be as smooth as possible. After the position of the dice is determined, determine the length of the crucible and the distance between the piles. The length of the body is 50m--65m, and the pure length of the anchor cable is 2 times -3 times of the water depth at full tide. The horizontal distance between the two piles of a rafter is twice the length of the body and the length of the other side of the right triangle formed by the anchor cable and the water depth. The distance between the two rafts is the pile spacing between adjacent piles. Different farming modes are different, some 2.5m--3.0m, some 4.5m--5.5m, so that the pile can be determined. Bit.

The pile foundation material varies depending on the bottom material of the sea area. The sand area with sand bottom should use pine with a diameter of 13cm and a length of 2m as the pile; the sea area at the bottom of the sediment should be about 16cm in diameter and more than 3m in length; the sea area in the soft mud bottom should be thrown 50kg--100kg iron anchor. . Note that the end of the bamboo should open the bamboo joint, and the length is about 1/3 of the total length. In addition to the iron anchors, each pile is drilled at the top to tie the pile rope.

Squat. Before the squatting, the anchor cable should be connected with the pile rope. The sling rope and the corresponding float should be tied to the sea every 50cm--60cm on the floating raft, and the cross rope should be reinforced on both sides of each gantry. The floating sling, the horizontal rope and the anchor cable are well connected, and then the loose rafters are arranged to make the spacing uniform, which constitutes a single truss. The tightness of the truss should be optimal at the highest tide.

The materials used in each district. In addition to the pile foundation, there are 2160 wire - 2800 wire polyethylene floating rope, horizontal rope, 180 wire polyethylene sling and 2800 wire - 3600 wire polyethylene pile rope, anchor cable and float.

4.1.2.4 Take seedlings, seedlings, and seedlings

time. When the water temperature drops to 27 ° C, it is about the end of September to the beginning of October.

Miao rope. 180 silk - 360 silk polyethylene rope, there are 3 strands of 3 flowers, 3 strands of 6 flowers in two forms, the twist of the seedling rope must be appropriate, too loose and easy to fall off the seedlings, too tight and easy to hurt the seedlings. The seedling rope should be treated a few days before the seedlings, that is, the new seedling rope is soaked in water for 1 day, and the old seedling rope is disinfected and washed with 200ppm bleaching powder.

Take the seedlings. Since the growth rate of the base of Asparagus is slower than that of the top, in addition to the selection of the asparagus, which has good growth, purple color and less algae, it is also necessary to use the base algae as seedlings. During the seedling period, the algae should be prevented from drying and the temperature should exceed 30 °C.

Clip seedlings. The cluster clamp method should be used. The amount of seedlings is 50g of asparagus with rice seedlings per meter. After removing the algae, the seedlings of the asparagus are about 5g as a small cluster through the seedling rope, and a cluster of seedlings is placed every 5cm--10cm. Sandwiched in the middle of the seedling, the ends are exposed 5cm-6cm. When the seedlings are clamped, prevent sun exposure and dry algae to prevent dehydration of the algae and exceed the upper temperature limit.

Hanging seedlings. Connect the ends of the clipped ropes to the slings on the floating raft.

4.1.2.5 Cultivation management

Water layer regulation. The adjustment of the cultivated water layer is actually to regulate the light receiving of the asparagus. Asparagus is a good light seaweed. The light is too slow to grow slowly, but too strong light has an inhibitory effect on growth. Even the pigment is decomposed by sunlight and fades to yellow. If it is not adjusted in time, it will turn off.

Adjust the truss. In addition to appropriate increase or decrease of buoyancy, the broken rope should be replenished in time; always pay attention to check the firmness of the truss, the tension of each raft should be consistent, and the requirements should be uniform to ensure production safety, and the asparagus is evenly exposed. .

Fertilization. The waters in the southern part of the sea are fertile and generally do not fertilize; however, in some seasons, when the nutrient salt in the local sea area is insufficient, the bag should be considered for fertilization.

After 2 months to 3 months of growth, the asparagus weight gain is more than 100 times. At this time, the algae body is thicker and the color is purple and black. When the rice seedling rope reaches 3kg, it can be harvested. Unless the pests and diseases are severely robbed, it is not advisable to harvest too early because the premature harvest of Asparagus has a low gel content. The harvest should be brought to the shore together with the seedling rope. It is not advisable to take the harvesting method and retain the base. It should be done on a sunny morning to ensure that the asparagus can be exposed in time without deterioration. If it is not dried on the first day, it must be dried on the next day so that it can be stored in bags.

4.1.3 Method of culture of Pacific oysters

Pacific oysters are broad-salt and wide-temperature inner bay shellfish, which are characterized by large individuals, fast growth, high yield and strong adaptability. Its soft body is plump, tender, delicious and has high nutritional value. South Australia is particularly suitable for the cultivation of Pacific oysters. According to incomplete statistics, almost all farmers are cultured Pacific oysters. The breeding methods include a long rope type, a pole type and a column type.

Mainly in the sea area, the main breeding measures are:

Sea area selection: According to the characteristics of Pacific oysters with large body size, small fixation points and poor resistance to wind and waves, we should choose sea areas with small wind and waves, smooth flow, no pollution, fresh water injection and rich food.

Set up and stocking density: set up in the downstream, each floating stem is 50-60 meters long, the spacing between the tables is 5 meters, 30-50 sets are connected to one area, the length of the pile stem depends on the water depth of the sea area, and the length of the pile is the tide. More than twice the depth of the tide. The waste foam plastic is used as a float, and a bunch of shellfish is suspended every 0.4-0.5 m on the floating stem. Each seedling string has 10 shells, each with about 10 capsules.

Daily management: First, the seedlings are protected in the early stage. After purchasing the seedlings, it is best to hold them in the local seawater ponds. The seedlings of the holdings are about 1 cm long, and they are raised in the sea area. Mud to avoid suffocating seedlings. The second is to remove the attachments and wash the sludge in time. As the water temperature rises, there are more attachments on the oysters, which hinders the filtration of the oysters and affects the growth. When cleaning and washing, it should be handled gently to prevent the oysters from falling off. Third, it is necessary to prevent the slings from being entangled and dropped between the strings. In the typhoon-prone season, do truss reinforcement and prevent the work.

4.1.4 Benefits of polyculture mode of Asparagus and oyster [3]

The culture of Pacific oysters in South Australia is very large. However, due to the high seawater salinity and insufficient technical level, the seedlings are poor. The general seedlings are generally imported from Fujian Province with high seedling technology. If the culture density of Pacific oysters is too large, the yield will decrease. After the oysters are cultured, their excretion will cause eutrophication of seawater. When mixed with Asparagus, the excrement can be absorbed by Asparagus. The oxygen that is spit out is used for oysters, while the asparagus can be fed by oysters.

During our interview, some land-based farmers raised their concerns about whether large-scale cultivation of oysters in the coastal areas would cause pollution of their inland aquaculture water sources. In fact, according to our research, this is impossible. Because, since the oysters and the asparagus have been mixed, the water quality is not only polluted, but the farmed wastewater that has been excluded from the land can be purified. So their concerns don't exist.

4.2 Shrimp and crab polyculture technology

The shrimps cultivated by the farmers in South Australia are mainly white shrimps and grass shrimps, and the crabs are mainly crabs.

4.2.1 Management of aquatic plants

Planting water plants in shrimp and crab polyculture ponds can play a role in blocking sunlight and lowering water temperature. At the same time, water plants can provide a large amount of vitamins and other nutrients, and one of the important bait for foot and crab to maintain healthy growth. The large amount of water grass can also be used as a concealer in the shrimp and crab clam shells, which is beneficial to reduce white-phase killing and increase survival rate. In addition, the growth of aquatic plants can absorb nutrients such as nitrogen, phosphorus and potassium in water, which is beneficial to reduce the content of harmful components such as ammonia nitrogen and nitrite, and improve the culture ecology of ponds. However, the species of aquatic plants in the past are mainly Eryza, which grows early, grows fast, is well-nourished, but is not resistant to high temperatures. The grass is particularly prone to decay during the hot summer season, and the decaying water grass will cause deterioration of water quality and proliferation of bacteria. The crab disease caused by this will cause significant losses, so measures must be taken to prevent it.

When the growth of aquatic plants is too lush, the water plants at the surface of 20 to 30 cm should be cut off in time, or measures such as ventilation should be adopted to reduce the biomass of the aquatic plants. This method can effectively solve the problem of decay of water plants in summer. When a large area of ​​water plants rots, the surface of the rotten grass can be cut off, and the bio-organic fertilizer is splashed, so that the water plants can resume growth as soon as possible. For ponds with a small number of water plants, some floating plants such as water peanuts, water hyacinth and duckweed can be replenished, and some high quality aquatic plants such as Hydrilla verticillata or Elodea can be replanted to improve the ecological conditions of the pond. 4.2.2 Water Quality Management [4]

A good water environment is an important guarantee for high yield and high efficiency of shrimp and crab polyculture. In the hot season, the water temperature in the pond is high, the water quality changes rapidly, and the water quality deteriorates often causes a large number of deaths of shrimps and crabs. Therefore, the shrimp and crab polyculture pond should change water more frequently and take corresponding water quality improvement measures.

Frequent water injection or water exchange can promote the exchange of water and achieve the purpose of stimulating the growth of shrimp and crab clam shells. When the water quality of the water source is poor, the pond water body must be disinfected and treated after water injection. The disinfectant can be selected from dibromohydantoin, bromochlorohydantoin, bromine-rich, strong chlorinated, bleaching powder, chlorine dioxide, povidone iodine and dioxygenated quaternary ammonium salt complex iodine. The concentration is 0.1-0.3. g/m3. The water injection time of the pond is preferably from 10:00 to 15:00. Water should not be added or changed after 17:00 in the afternoon. This will cause the oxygen in the surface water to be consumed in advance due to the convection of the water. In the evening, the oxygen-deficient floating head will appear. phenomenon.

Ponds with less water plants often produce a lot of cyanobacteria. At this time, it is difficult to improve the water quality by changing the water alone, and it will promote the outbreak of cyanobacteria. It can be sprayed twice a day with a concentration of 0.4 g/m3 of strong chlorine or chlorine dioxide. Control it. If a large amount of cyanobacteria has been found to have died in the pool, the shrimp and crab should be arrested and listed as early as possible to reduce losses. If the water source has good water quality, it can be solved by completely changing the water.

For ponds with deteriorating quality, multiple sediments and biological agents can be used to adjust to ensure the normal growth of shrimps and crabs.

4.2.3 aeration

The shrimp and crab polyculture ponds must be equipped with an aerator or water pump. When the weather is very hot, the aerator should be turned on at noon to fully oxidize the oxygen-consuming organic matter at the bottom to improve the dissolved oxygen in the evening. If the oxygen is turned on after midnight, it must be turned on until the daytime to shut down. If it is rainy or cloudy, it must be continuously oxygenated throughout the day to prevent the death of shrimp and crab. In addition, appropriate amounts of chemical oxygenators should be provided during the cultivation of shrimps and crabs to prevent accidental anoxic accidents.

4.2.4 Feed Management [5]

Excessive feeding often causes a large amount of feed to be deposited at the bottom of the pool and causes deterioration of the ecology of the sediment and water. Feeding animal feed is more likely to pollute water than feeding plant-based feed. Therefore, the feeding of shrimp and crab polyculture ponds should pay attention to the following items: 1 High-quality pellet feed, with plant feed; with late end to 9 At the beginning of the month, the supply of animal feed can be increased, but the bait should be disinfected. It can usually be soaked with 20 mg/L potassium permanganate for 10 minutes to kill the bacteria. 3 Periodically spray biological agents or bio-organic fertilizer to improve the water ecology. To prevent the occurrence of diseases; 4 in the sweltering thunderstorm days or a large number of clam shells of shrimps and crabs should reduce the feeding amount of feed to prevent the remaining feed from polluting the pool water and the bottom of the pool to cause the disease of shrimps and crabs; 5 adding 1% to the feed 2% of allicin or 1% to 5% of biological agents and other non-polluting drugs to prevent disease, if the disease has occurred, 1% can be used. The florfenicol is mixed with the bait for treatment, but should be stopped 1 month before the start of the arrest to prevent drug residues. 6 In order to reduce the damage of the pond ecology to the residual bait, an attractant can be added to the feed to improve the utilization rate of the feed.

4.2.5 Farming experience of local farmers

Experience 1: The southwest wind is suitable for breeding. The high temperature can make the shrimp and crab grow fast, 25-30 degrees Celsius is the most suitable, but the high temperature is easy to make the seawater deteriorate, and the water should be changed frequently.

Experience 2: 2-3 times a day. Using tools to test whether the feed is suitable can prevent the waste of feed.

Tool: Place the feed in a disc-shaped meshed tool. Put it in the water. After 2-3 hours, there is still no need to look at the feed to judge whether the feed is suitable. On the one hand, it can ensure that the shrimp and crab are full. On the one hand, it can ensure that the feed is not wasted, and the excess feed will prevent the eutrophication of the seawater and pollute the seawater. .

Experience 3: When the red tide occurs and the water cannot be changed, only the disinfectant can be added. The disinfectant is the “degradation spirit”. Its main function is sterilization and adjust the pH value. See the photo for specific ingredients. Use ph test paper to measure ph value. After rain, it is acidic. The pH value can be adjusted by syrup or lime. Neutral is the best.

Experience 4: Winter is not suitable for breeding, you should put the water to the bottom of the pool, you can disinfect. When there is fog in spring, it is easy to lack oxygen and need oxygen. At 3 or 4 in the morning, the air pressure is low and oxygen is required.

Experience 5: Generally, small fish are added with feed, of course, small fish is better.

5. Research summary and recommendations

After this investigation, we found that the aquaculture industry on Nan'ao Island has matured. Regardless of inland farming or offshore aquaculture, farmers have mastered certain farming techniques and have rich farming experience. According to their reports, although the water quality has deteriorated in recent years due to global influence, compared with other areas, the water quality in the offshore areas of Nan'ao Island is still very good. In particular, it can be said that there has been almost no large area of ​​explosion in the past decade. The red tide phenomenon, the breeding status tends to be good. The farming income of farmers in recent years has tended to be stable, and the farming confidence of farmers has also increased.

Suggest:

1 The government may set up a breeding fund to help raise the problem of farmers' owing in special circumstances, such as typhoons or other geological disasters.

2 Farmers can organize their own breeding federations to provide a platform for exchanges for farmers to exchange experiences on a regular basis.

6 Acknowledgement

The survey was supported by local farmers in South Australia. Thanks to their active cooperation, our hungry research activities were carried out smoothly. I am also very grateful to the local authorities for providing us with some local farming materials, which makes our research more purposeful and targeted. I would like to thank all the units and individuals who have supported and assisted this research!

7 reference tools

[1]Xu Guo. South Australia became the largest Pacific oyster breeding base in Guangdong [j]. Aquatic Science and Technology Information, XX,

[2] Meng Wei, Song Jianzhong, Qu Hongxia, Wang Dezhi, Zhang Dongjie. A new model of shallow sea culture——Pacific oysters easy to fatten [j]. Chinese aquatic products, XX,

[3] Li Jing, Gao Weiming, Yang Huili. Impact of seawater pond culture on coastal ecological environment——Taking Hebei Province as an example [j]. Marine Development and Management, 2010,

[4] Li Zhongbao, Wu Zhongqing. Comparative study on the heterozygosity of several elite cultured shrimps. Marine Science, XX

[5] Wang Ligong, applying ecological principles to comprehensively rule shrimp disease [j]. Scientific fish farming, XX,