How to Increase Yield in Crayfish Farming

In recent years, artificial crayfish farming has begun in many regions of China, but yields vary widely, with high yields reaching 400-500 kg per mu and low yields of only a few dozen kg. To improve the survival rate of farming and achieve high quality and high yield, the following main technical measures must be mastered.

1 Reasonable farming density

Maintaining a reasonable farming density is not only conducive to fully tapping the pond's productivity, but can also increase the yield, size and economic benefits of the crayfish. If one-sidedly pursues yield by increasing farming density, it will increase the difficulty of farming management, and crayfish will also kill each other while competing for living space. The large amount of leftover bait and excrement produced by high-density farming will also degrade water quality, further shrinking the living space for crayfish. The pond environment has a relatively large impact on crayfish burrowing. Under conditions of relatively fertile water, more bottom mud and abundant organic matter, burrows decrease, which can also lead to crayfish killing each other. Generally speaking, the reasonable farming density for pond monoculture of crayfish is: in spring (February-March), stock 30,000-40,000 juvenile crayfish of 2-4 cm per mu of water surface; in summer (July-August), generally do not stock juveniles, but stock high-quality parent crayfish, 20-25 kg per mu of water surface, with a male-to-female ratio of 3:1; in autumn (September-October), stock 30,000-50,000 juveniles just leaving their mothers (body length 10-12 mm) per mu of water surface.

2 Stocking sizes should be basically consistent

When stocking crayfish, note that the stocking sizes should not differ too greatly; otherwise, large, medium and small sizes must be stocked separately in three types of ponds. During the grow-out process, also pay attention to the size of the crayfish. If sizes are uneven, large crayfish will eat small crayfish, greatly reducing the survival rate and affecting the improvement of farming yield.

3 Correct feeding

Feeding is key in crayfish farming. When feeding, attention should be paid to five aspects: the type of bait, the palatability of the bait, determination of the feeding amount, the feeding method and the feeding time. Crayfish are omnivorous animals and can consume both animal-based and plant-based bait. In farming production, some cereal and grass plant-based bait and animal-based feed such as live river snails are usually fed. Crayfish are rather greedy feeders. Insufficient feeding not only affects the normal growth of crayfish, but also leads to cannibalism, so it must be ensured that crayfish can consume enough bait and that the bait is fresh. Excessive feeding or improper feeding methods will cause bait waste and degrade water quality. Generally, the feeding amount is calculated according to the body weight of the crayfish in the pond. In the peak growth season (April-September), the feeding amount is 7%-8% of the crayfish body weight, and in other seasons it is 1%-3% of the body weight. In actual feeding, the amount should be flexibly adjusted according to specific conditions, such as weather conditions, water quality, the amount of aquatic animals and plants in the pond, and the amount of leftover bait. Crayfish have the habit of hiding by day and coming out at night, often emerging at night to move and feed, and generally hiding among aquatic plants to rest during the day. Therefore, generally around 9:00, feed 20%-30% of the total bait amount, and around 17:00, feed 70%-80%.

4 Improve water quality in a timely manner

Wild crayfish often live in foul ditches, and many farmers mistakenly believe that crayfish have strong pollution tolerance and can survive under relatively poor water quality conditions. In fact, excessively poor water quality conditions will reduce the constitution and vitality of crayfish. During crayfish farming, the pond water transparency should be maintained at 30-40 cm, the pH value at 7.5-8.5, and dissolved oxygen above 3 mg/L. For this reason, water quality management should be strengthened, new water should be added frequently, and quicklime slurry should be splashed once every 15-20 days at 3-5 g per cubic meter of water to regulate water quality, increase the content of ionic calcium in the water, and provide the calcium needed for crayfish molting and growth. Once the pond water becomes aged, it should be replaced in a timely manner to keep the pond water “fertile, lively, tender and refreshing”, promoting timely molting and growth of crayfish. When water temperature is suitable and bait is sufficient, juveniles generally can reach a commercial size of about 20 g each in 60-90 days.

5 Increase hiding places

Crayfish are naturally fierce and have a strong habit of occupying territory. When there are not enough burrows and aquatic plants for them to hide or conceal themselves, cannibalism becomes extremely serious. Taking advantage of the crayfish's burrowing habit, building artificial burrows can effectively prevent crayfish from killing each other. Artificial burrows can be built on slopes below the water level, with an opening diameter of 6-10 cm and a depth of 15-30 cm. Crayfish also have the habit of clinging to aquatic plants. Planting or placing aquatic plants such as alligator weed, hydrilla, water hyacinth, pondweed and water lettuce in the farming pond can not only provide hiding places for crayfish, but also increase their living space and reduce mutual killing. At the same time, aquatic plants can also serve as food for crayfish, reducing the consumption of artificial feed and saving farming costs.