The cultivation of juvenile crabs in plastic greenhouses serves as a foundational technique for developing various crab farming models. It plays a crucial role in increasing the size of marketable crabs and improving the survival rate of seedlings. This method is based on the biological needs of young crabs, offering an optimal ecological environment—such as water plants, suitable water temperature, and adequate feed. By doing so, it not only enhances ecological benefits but also boosts economic returns.
This eco-agricultural model can be implemented on underutilized lands, such as coastal or inland wastelands and abandoned areas. It helps improve land use efficiency while simultaneously enhancing both ecological and economic outcomes. The social impact is also significant, making this approach a sustainable and valuable solution for rural development. Below are the key technical aspects of the model.
**I. Greenhouse Construction and Preparation**
1. The pool area for scaffolding is typically 0.5 to 1.0 mu (667 square meters), with a depth of 0.8–1.2 meters and a water depth of 0.3–0.8 meters. The pools should be oriented east-west, with a flat bottom and a slope ratio of 1:1.5. A steel or bamboo frame greenhouse is installed, with large mesh films secured around the edges and buried into the soil. A bamboo bridge is placed in the center, 30 cm above the water surface for easy management and feeding. Two air pipes are installed 20 cm from the pool bottom, with air holes drilled every 25 cm. A heating boiler is used during winter to maintain optimal temperatures.
2. Before planting, wild and desolate fields should be desilted and sun-dried. About 10 days prior to planting, 250 kg of quicklime per 667 square meters is applied to purify the soil.
3. Aquatic plants such as water peanuts, bitter grasses, or disinfected willow roots and brown skins are transplanted to provide shelter and attachment points for young crabs. These plants should cover 40–60% of the water surface.
4. One week before introducing feed, the water is filtered through a 60-80 mesh sieve, and the inlet water level is set to 30 cm. Chicken manure (50 kg) and urea (5 kg) are added per 667 square meters to cultivate natural food sources.
5. Water temperature inside the greenhouse should be maintained at 22–28°C. When introducing crabs, the temperature difference between the greenhouse and the nursery pool should not exceed 3°C.
**II. Seedling Introduction**
Typically, 5–10 kg of seedlings are introduced per 667 square meters. The crabs should be uniform in size, healthy, and free from damage. Before placing them in the water, they should be sprinkled with water 3–4 times or soaked in a bath for 2–3 minutes each time to acclimate.
**III. Production Management**
1. Within the first 15 days, the water level should be kept at 36 cm, then gradually increased to 80 cm. In the middle and late stages of culture, water should be changed daily by 50–80%.
2. Water quality should be maintained by using fertilizers, live organisms, and cooling methods. Water transparency should be kept at 40–50 cm.
3. Feeding starts one week after seedlings are introduced. Initially, egg yolk, milk powder, and fish worms (copepods) are fed at a rate of 150–100%. As crabs grow, the feeding rate decreases: 80–50% for II–III stage crabs, and 30–15% for IV–V stage crabs. Feedings occur 5–7 times per day for I–II stage, 3–4 times for II–III stage, and once or twice for IV–V stage.
4. Disease prevention involves applying 5–10 kg of lime per 667 square meters monthly. A mixture of 1% furazolidone or oxytetracycline is mixed with bait for 2–3 days. During the molting period, reduce water changes.
5. Daily inspections are essential. During hot seasons, open the greenhouse doors from 9 am to 3 pm for ventilation and oxygenation, and change water regularly.
**IV. Harvesting Juvenile Crabs**
Juvenile crabs are usually cultured for about 30 days, reaching a weight of 2,000–5,000 per kilogram. They can be harvested according to customer demand using methods like drainage collection, netting, or manual picking.
**V. Benefit Analysis**
The growth rate generally ranges from 20% to 40%. On average, 80–120 kg of juvenile crabs can be produced per 667 square meters, with an output value of 2.5–4 million yuan and a profit of 8,000–15,000 yuan per 667 square meters.
**VI. Challenges and Suggestions**
1. Place seedlings in shallow water with sufficient vegetation.
2. Purchase high-quality seedlings to ensure a high survival rate.
3. Keep aquatic plants fresh, ensuring they cover at least 30% of the water surface.
Glacier Nine Degrees Beer
Glacier Nine Degrees Beer,Lime Glacier Nine Degrees with Friends,Icy Beer for Hot Summer Days,Smooth Glacier Nine Degrees for Lazy Saturdays
Yanbian Baichuan Import and Export Trade Co., LTD , https://www.baichuanbeer.com