The scientific name of the river crab is *Eriocheir sinensis*, commonly known as the Chinese mitten crab. It is highly valued for its delicious meat, rich nutritional content, and potential medicinal benefits. With a strong domestic demand and significant economic returns, crab farming has become a promising industry, especially in northern regions where it can be successfully cultivated with proper techniques.
So, how can you breed crabs in the north? Here are the key steps and considerations:
First, selecting high-quality seedlings is crucial. In China, crabs from the Yangtze River system are considered the best for breeding. Crabs from the Liaohe or Zhejiang River systems are not recommended for introduction due to their lower adaptability. Before purchasing, ensure that the seedlings come from a reputable source and have undergone strict quarantine to avoid introducing diseases.
Second, there are two main breeding methods: pond culture and rice field farming.
1. **Pond Intensive Culture**
- **Pond Selection**: Choose a pond with a clean water source, stable water level, good transparency, and sufficient dissolved oxygen. The area should support aquatic plants like water grasses and snails.
- **Stocking**: Disinfect the pond for 15 days before stocking. It’s best to introduce seedlings during rainy days or early morning/evening when temperatures are cooler. For 2nd instar crabs (around 5g), stock 2000–3000 per acre. Adult crabs can be stocked at 0.8–1 kg per acre. You can also add a small amount of squid to enhance biodiversity.
- **Feeding Management**: Use high-protein compound feed (over 35% crude protein) or natural food sources such as fish, silkworm pupae, snail meat, and slaughterhouse waste. Include plant-based feeds like vegetables, grains, and bran. Feed once daily in the evening, placing food near the waterline at 3–5 points per acre. Adjust feeding amounts based on the previous day’s intake, typically 3–5% of the crabs’ body weight.
2. **Rice Field Crab Farming**
- **Field Preparation**: Select fields with good water quality, sufficient irrigation, and strong water retention. Use rice varieties that are resistant to lodging and disease.
- **Stocking Process**: Two weeks before stocking, remove silt and debris, then disinfect using 150g of quicklime and 50g of tea bran per square meter. Apply lime first, then sprinkle tea bran soaked overnight.
- **Feeding and Management**: Immediately after stocking, feed crabs with a mix of bean cake, wheat bran, and small fish or snail meat. Animal by-products like fish scraps can also be used. Feed once daily in the evening, with an average of 3% of the total weight. Maintain a water depth of at least 30 cm, increase it during hot weather, and change water every 15–20 days. Regularly inspect for issues and implement anti-predator measures.
Third, several important precautions must be taken during the breeding process:
- **High-Quality Seedlings**: Avoid cheap, low-quality seedlings from unverified sources, as they can lead to poor growth and lower profits.
- **Prevent Early Maturation**: Overfeeding, poor water quality, and incorrect stocking density can cause crabs to mature too quickly, reducing their market value. Control feeding amounts, maintain good water conditions, and regulate temperature.
- **Water Quality Management**: Keep the water clear (30–40 cm visibility), free of pollution, and well-aerated. Plant aquatic vegetation to provide shelter and improve habitat.
- **Disease and Predator Control**: Regularly apply lime to control pathogens. Avoid pesticides and fertilizers, as crabs are sensitive to them. Protect against predators like birds, frogs, and rodents.
Fourth, effective escape prevention and harvesting are essential. Use durable materials like fiberglass tiles or calcium plastic panels for pond fencing. Avoid plastic films due to their tendency to degrade. Conduct daily inspections, check for leaks, and remove leftover food and dead crabs promptly.
Harvesting should occur around mid-September, typically in the evening. Methods include trapping with light, netting, manual collection, or water fishing. After harvest, place crabs in small enclosures or temporary boxes for sale.
In conclusion, with proper management, crabs raised in this system can reach 100–180g in size by autumn, with a high catch rate and significant economic returns. This makes crab farming a viable and profitable option for northern farmers.
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