Ecological polyculture technology of shrimp shrimp in marine ponds
Wang Hua and others
Ginseng is one of the important marine cultured species in northern China and has significant economic benefits. Pond culture of traditional single species of thorn ginseng has problems such as predator infestation, large quantities of natural bait are difficult to be fully utilized, and idle water resources in ponds during the summer dormancy period are wasted. In recent years, predators have gradually become the main factor affecting the cultivation of ginseng ponds, especially the breeding of small arthropods such as copepods and hook shrimp compete with the living space of farmed ginseng, invade the surface of ginseng, interfere with the normal feeding growth of ginseng, and cause the epidermis of ginseng to fester until the skin dies.
Since 2014, the team has carried out experimental research on ecological polyculture with ginseng as the leading species, and established an ecological breeding model of ginseng-shrimp by taking advantage of the characteristics of shrimp feeding on haplopods such as copepods in the pond. This is a multi-trophic level ecological green breeding model, which will be in different ecological niches of multi-trophic levels of breeding, can make full use of bait, space and other resources, improve the utilization efficiency of materials and energy in the system, and obtain greater economic benefits. After years of improved maturation, this technology has become more and more mature, and is currently promoted and applied in more than 80,000 mu in the ginseng breeding area of Shandong Province, with significant economic and ecological benefits. The advantages and technical points of this model are introduced by taking the ecological polyculture of Ginseng-Vannabin shrimp and Nippon shrimp in 2020 as an example.
1. Materials and methods
(1) Pond environmental optimization
The test pond is a breeding pond of Laiyang Ocean Fishery Co., Ltd., located at the mouth of the Wulong River, which can naturally absorb tide, facilitate inlet and drainage, and have excellent water quality. The test pond has an area of 60 mu, a depth of 2 m, and a hard sediment bottom. Clear the pond 30 days before the seedlings are released to remove predators and pathogenic microorganisms of ginseng and shrimp. Pond water inlet to 60 cm ~ 80 cm water level, appropriate application of nitrogen, phosphorus inorganic fertilizer water, transparency to maintain 25 cm ~ 40 cm. The water inlet is equipped with 2 barriers of 40 mesh to 60 mesh. Breed bait organisms before seedling release, transplant suitable algae, and moderately cultivate small arthropods such as cockroaches and hook shrimp. Single-cultured ginseng ponds adjacent to the test ponds and under the same conditions were selected as control ponds.
(2) Seed selection and medium cultivation
Select high-quality Penaeus vannas and Nicholas nigra seed, check the parent test report and seed production testing records to ensure that the fry meet SPF standards and disease-free levels. The seedlings are appropriately marked in the early stage, under the following conditions: water depth of more than 1m, dissolved oxygen is not less than 5mg/L, the transparency of pool water is 25cm~40cm, and the water color is light green or yellow-green. The size of The Vannas shrimp seed is about 1.5 cm, and 2000 fish per mu are stocked, while the size of the Japanese shrimp fry is above 1.0 cm, and 750 fish are stocked per mu. Select high-quality ginseng seedlings, the specifications are 5g/head~10g/head, and 2000 heads are stocked per mu. On April 7, 2020, when the water temperature in the pond is suitable, the Japanese shrimp seed is first stocked, the ginseng seedlings are stocked from April 18 to 20, and the Vanabin shrimp seedlings are stocked on May 5, and the seedling release time is selected in the morning of sunny days.
(3) Environmental regulation and control
From April to May, the amount of water exchange will be reduced, and after June, the amount of water will be increased according to the quality conditions of the inlet water. When the dissolved oxygen of the pond is less than 4mg/L in summer, the waterwheel aerator can be used for oxygenation to solve the problem of water temperature and dissolved oxygen stratification during the high temperature period. Timely adjust the water level, create water temperature conditions for the growth of breeding objects, increase light transmittance, promote the reproduction and growth of benthic diatoms and beneficial bacteria, and increase the biomass of bait in the pond. Pay attention to the disinfection treatment of the pond, apply quicklime, etc. to regulate the water quality, improve the substrate, and create a good ecological environment for the animals bred in the pond.
(4) Daily management
The daily management adheres to the daily morning and evening pond patrol system, monitors the changes in the pond water environment and the feeding and activities of ginseng and shrimp, and checks whether the breeding facilities are operating normally. Do a good job of production logs, and make complete records of meteorology, water temperature, water quality, management, drug use and use methods. Timely application of immune enhancers, etc., to increase the disease resistance and immunity of ginseng and shrimp. Random sampling of ginseng, shrimp growth, feeding and survival rates every 1 month.
2. Results and analysis
(1) Breeding results
Monitoring the survival rates of Ginseng, Penaeus vannamei and Nichopsis in the polyculture process, it can be seen from Table 1 that the survival rate of ginseng in ecological polyculture is more than 85% per month, which is not significantly different from the monoculture model; the final survival rate of Vannabin shrimp is 74.6%. Japanese shrimp was 68.4%.
Table 1 Survival rates of Ginseng, Penaeus vannas and Nicholas nigricans in different patterns
The growth of ginseng in the polyculture mode of ginseng and shrimp is shown in Table 2. During the experiment, the weight gain of ginseng in the monoculture mode was significantly lower than that in the ecological polyculture mode. In the summer heat, Vanabin and Nicholas nigricans feed vigorously, and their excreta and other organic detritus settle to the bottom of the pond, which to a certain extent promotes the feeding activities of ginseng and reduces growth stagnation caused by sleep.
Table 2 Growth of ginseng in different ecological culture models
(2) Benefit analysis
After 5 months of breeding, the polyculture pond harvested a total of 2136 kg of Vannabin shrimp, the yield per mu was 35.6 kg/mu, according to the average price of 50 yuan / kg, the average output value of 1780 yuan per mu; Japanese shrimp 462kg, mu yield of 7.7kg / mu, according to the average price of 180 yuan / kg, the average output value of 1386 yuan per mu. Because this model does not require bait, the increased cost is only shrimp fry, mesh, labor costs, drugs and other costs, about 700 yuan / mu, therefore, only polyculture shrimp new profit of about 2460 yuan / mu. At the same time, the growth rate of large-scale ginseng seed in the ecological polyculture mode is also higher than that of the monoculture mode, and the introduction of shrimp has also increased the additional benefits of farmed ginseng.
3. Discussion
(1) Pattern analysis
Ginseng is a typical benthic animal that makes full use of organic detritus that settle to the bottom of the pond and the excrement of other aquatic animals. In single-species pond culture systems, where the bottom nutrients are mainly derived from pond inlet and drainage, in ecological polyculture pond culture systems, ginseng can use detritus such as organic particulate matter from other farmed animals. In shrimp and other types of polyculture, the utilization rate of nitrogen and phosphorus by cultured organisms is improved compared with that of conventional single species culture, and ginseng plays the role of "scavenger" at the bottom of the pond in the breeding system, which can improve the quality of the water environment at the bottom of the water body.
In this model, 2 species of farmed shrimp are active in the middle and upper water bodies of the pond, feeding on the natural food in the pond, and their metabolites can be reused by the ginseng at the bottom of the pond to promote the growth of ginseng and improve the water and substrate conditions, so as to achieve the whole process of breeding without bait. At the same time, the agitation of shrimp in the water body increases the amount of dissolved oxygen and promotes the growth and metabolism of ginseng. Japanese shrimp has the habit of submerged sand and benthic activities, Vanabin shrimp like to move in the middle layer of water bodies with abundant bait, and the bottom spines participate in the ecological polyculture of multi-species shrimp, which makes full use of the water body space of pond culture, and achieves the effect of ecological environmental protection while making full use of breeding resources.
(2) Pay attention to the problem
In this model, the pond culture objects are mainly ginseng, and the stocking of ginseng seed does not need to be reduced compared with the single pond. At the same time, the density of shrimp fry should not be too large, especially the density of Japanese shrimp is generally within 1000 fish/mu. The ecological environment regulation of the pond should be mainly suitable for the growth of ginseng, taking into account P. vannabin and P. Nicholas. Summer ginseng culture should maintain a certain pond water level, and shrimp have no special requirements for pond water level, so the water level adjustment should depend on the growth of ginseng and the overall environment of the pond.
One of the advantages of multi-species ecological breeding in ponds is that it can effectively control the breeding of predators, and the hedgehog predators such as copepods, hook shrimp and cockroaches in the culture ponds are very ideal biological bait for Penaeus vannabin and Nicholas nigricans, without the need for additional feeding of shrimp. Ginseng is the most important source of economic benefits in culture ponds, so the culture of ginseng should be placed first.
(3) Prospects
Compared with the traditional single culture of ginseng, this technology can give full play to the advantages of each ecological niche breeding object in the multi-trophic hierarchy system, highlight the scavenger role of ginseng in the ecosystem, and realize the mutual benefit and symbiosis of the breeding objects at various nutrient levels. Its comprehensive breeding efficiency per unit area can be increased by more than 30% compared with the traditional single culture model, which can not only greatly improve the utilization rate of various resources in the pond area, reduce production costs, but also effectively reduce the impact of aquaculture waste on the marine environment, reduce the harm of pond predators, reduce the incidence of diseases, and ensure the quality and safety of aquaculture products. Through the adjustment of aquaculture species, the industrial structure can be further optimized, and the overall transformation and upgrading of the marine aquaculture industry can be promoted, and the quality and efficiency can be improved, which is in line with the current national requirements for the green development of marine aquaculture, and the promotion prospects are broad.