Sharing Experience in Northern River Crab Farming Management

The scientific name of the river crab is Chinese mitten crab (Eriocheir sinensis). Its flesh is delicious and nutritious, and it has certain medicinal value. Domestic market demand is large, economic returns are considerable, and farming prospects are broad. But we all know that the weather in the north in winter is much colder than in the south, so how do you farm crabs in the north?

Experience in Northern River Crab Farming Management

1. Seedling selection: At present, in our country, river crab seedlings from the Yangtze River system are considered the best, while river crab seedlings from the Liao River system and Zhejiang system are not suitable for introduction and farming. In addition, seedlings must undergo strict quarantine; do not introduce and farm diseased river crab seedlings. 

2. Farming methods: At present, river crab farming mainly adopts two methods: pond farming and rice paddy farming. 

1. Intensive pond culture 

① Pond selection and renovation: River crab farming waters require fresh water quality and water sources, stable water levels, no pollution, high transparency and dissolved oxygen, convenient drainage and irrigation, and abundant aquatic plants and aquatic animals such as snails and shellfish. 

② Stocking: After the pond is cleared and disinfected for 15 days, choose cloudy and rainy days or times when the temperature is low in the morning or evening each day to release seedlings. Stocking density: release 2-year-old juvenile crabs (individual weight 5 grams) at 2000-3000 per 667 sq m (1 mu); when stocking crab seedlings, release 0.8-1 kg per 667 sq m. An appropriate amount of silver carp and bighead carp can be stocked at the same time. 

③ Feeding management: Feed artificial compound feed. At present, specialized compound feed with a crude protein content above 35% is mostly used in various places. Animal feed such as fish, silkworm pupae, earthworms, snail and mussel meat, slaughterhouse offal, or other animal carcasses can also be fed. Appropriately feed plant-based feed such as aquatic plants, vegetables, grain, rice bran, and wheat bran. The feed fed is required to be fresh and not moldy, with balanced nutrition. When feeding, place the feed on the slope near the water level line or in shallow water. Set 3-5 feeding points per 667 sq m, feed once every evening, and the feeding amount is 3%-5% of body weight. Adjust the feeding amount according to the food intake of the previous day. 

2. Rice paddy crab farming 

① Field selection: Choose fields with sufficient water sources and good water quality, no pollution, convenient drainage and irrigation, and strong water retention. Rice planting requirements: choose varieties with excellent rice quality, small leaf opening angle, hard stems, strong fertilizer tolerance, lodging resistance, and disease resistance. 

② Crab seedling stocking: 15 days before stocking, remove silt and debris, and disinfect with quicklime plus tea seed cake. Use 150 grams of quicklime and 50 grams of tea seed cake per sq m. First sprinkle quicklime, and the next day sprinkle tea seed cake that has been soaked for 24 hours. 

③ Feeding management: Feed must be given as soon as the crab seedlings are put into the field. Feed small fish or snail and mussel meat mixed with soybean cake and wheat bran, or feed compound feed or animal-based feed such as slaughterhouse offal. The daily feeding amount depends on food intake and is generally 3% of total body weight, fed once a day in the evening. Under normal circumstances, rice fields used for crab farming should maintain a water depth of more than 30 cm, and the water level should be deepened in high-temperature seasons; change the water once every 15-20 days to keep the water quality fresh; patrol frequently, deal with problems promptly when found, and do a good job in preventing escape, theft, and natural enemies. 

Precautions for Crab Farming 

1. Purchase high-quality crab seedlings 

The quality of crab seedlings determines the quality of the final adult crabs. Never buy cheap crab seedlings from improper channels for farming! You should know that in the end the ones who suffer are the crab farmers themselves! 

2. Prevent precocious sexual maturity in river crabs 

Precocious sexual maturity in river crabs will lead to reduced quality of adult crabs and lower returns. The main causes of precocious sexual maturity in river crabs are poor quality crab seedlings, excessive feeding, and poor water quality. Preventive measures are: 

① Control feeding amount and feed quality. 

② Control stocking density. 

③ Control water quality and water temperature. 

3. Pay attention to water quality regulation and reduce burrowing by river crabs 

Choose a quiet place with sufficient water sources, good water quality, transparency of 30-40 cm, no pollution, and suitable water temperature for farming. Crab farming water bodies should consist of deep and shallow parts, and aquatic plants should be planted in the water. Pay attention to feed nutrition, combining green, rough, and concentrated feed. 

4. Prevent disease and natural enemies 

Regularly splash quicklime, about once every 20 days. River crabs are sensitive to pesticides and chemical fertilizers, so use as little or no pesticides as possible (such as dimethoate, trichlorfon, etc.). Rice paddy crab farming should also use less chemical fertilizer to avoid losses. 

Damage to river crabs by natural enemies generally includes rodent damage, frog damage, bird damage, etc. Effective protective measures should be taken to keep river crabs away from the threat of natural enemies. 

Escape Prevention and Harvesting of Crabs 

Escape prevention is one of the keys to successful crab farming! For escape prevention facilities, fiberglass tiles or calcium-plastic boards are better. Although plastic film is economical, it ages easily, has poor firmness, and is easy to damage. Moreover, holes are not easy to find and can easily cause crab escapes. Patrol the pond frequently; more care brings more harvest. Persist in patrolling the pond once in the morning and once in the evening every day, often observe the feeding and activity of river crabs, regularly check the escape prevention situation, especially do inspection work before rain and wind, and repair holes promptly when found. Remove residual bait and dead crabs in time. 

Harvesting should be carried out at the appropriate time (around mid-September, collected in the evening). 

There are various harvesting methods, which should be selected according to actual conditions: 

1. Trap capture (using the phototactic characteristics of river crabs). 

2. Crab cage capture. 

3. Water release capture (river crabs like water flow, suitable for catching button crabs). 

4. Cast net capture or direct manual capture by hand. 

In summary, under such a stocking model, if managed properly, the size of river crabs mature after autumn can reach 100-180 grams, and the recapture rate is also very high. If commercial crabs are raised according to size grade standards to small surround nets or temporary holding boxes for temporary holding and marketed at the right time, the economic benefits are very considerable!