CATDOLL : CATDOLL: What is the ratio of crab seedlings to adult crabs?

1. What is the ratio of crab seedlings to adult crabs?

The authentic crab seedlings weigh about 5-10 grams each. After 4-5 moltings in 4-5 months, the adult crabs weigh 75-200 grams each, and the weight gain is 15-25 times. The weight gain of female crabs is less, while that of male crabs is more. In the actual production of river crab farming, the net weight gain is 7-15 times, excluding some river crabs that were injured or killed during the farming process. Provided by Erli River Crab Farming Base.

2. How to catch river crab fry?

Crab seedlings are highly seasonal. Generally, the peak season lasts only two or three days. Therefore, whenever the flood season is approaching, there must be someone on duty to observe and test catch crab seedlings. Once crab seedlings are caught, they will be organized to catch them immediately. The main fishing tool is "fishing in the sea". A circular net for catching fish seedlings, which uses a combination of fixed positioning and lighting to catch seedlings, has a better effect. The survival rates of the scooped crab seedlings after being out of water for 24 hours, 36 hours, and 48 hours were 90%, 60%~80%, and 30%~50%, respectively. Therefore, the caught crab seedlings should be transported as quickly as possible. If they cannot reach the destination on the same day, they should be kept temporarily.

3. What preparations should be done before releasing river crab seedlings?

The quality of the preparation work before stocking crab seedlings directly affects the survival rate and metamorphosis rate of crab seedlings after they are put into the pond. Pond cleaning. Pond cleaning should be carried out in winter as much as possible, and the cleaned pond should be allowed to dry, freeze and expose to the sun. Escape prevention. Before disinfecting the breeding pond, build an escape prevention wall to prevent harmful organisms from entering the pond after disinfection. Disinfection. Before stocking, use drugs to clean the pond and kill harmful organisms and pathogens in the pond. Planting grass. 20 days before the crab seedlings are put into the pond, plant aquatic plants all over the pond bottom, and lay out aquatic plants such as water peanuts. Fertilization. 7-10 days before the crab seedlings are put into the pond, fill the pond with 30-40 cm of water, fertilize, and cultivate natural bait. Stocking. Before stocking, the stocking amount of each pond should be determined, and each pond should be stocked at one time. If they are not stocked at the same time, the size of the crabs in the early and late stages will be too different, resulting in food grabbing and cannibalism.

4. What is the method of transporting river crab seedlings?

At present, all places use dry transportation, and only spray a small amount of water to moisten. The water used can only be river water or river water. Tap water cannot be used. If there is no river water, tap water should be placed in a tank in advance to "gas and volatilize the chlorine and remove the iron. The box for crab seedlings is made of wood boards with window screens, 63 cm long, 46 cm wide, and 8.5-10 cm high. There is a 3.5-10 cm opening on each side.

5 x28 (or 14) square centimeters rectangular screen. This specification of crab seedling box can generally hold 1 ~ 1. 25 kg. If the road is close, the amount can be increased appropriately. If the road is far away and the seedlings are temporarily raised, the dead and living seedlings should be separated, so as to improve the survival rate of transportation. The following aspects should be paid attention to during transportation: First, short-distance transportation does not need to be temporarily raised, and it can be transported as soon as it is caught; long-distance transportation must determine the transportation route and location, and try to shorten the transportation time.

Second, before loading the seedlings, check the seedling container to see if it is worn out or cracked, and wash and soak the seedling box. Third, when putting the crab seedlings into the container, the crab seedlings must be loosened to prevent the crab seedlings from being stuck to their limbs by water. Fourth, when transporting by car or train, the windows and doors on the car must be closed, and the windows and doors must be opened when parking. Otherwise, when the car is moving fast, the wind is strong, which is not conducive to maintaining a certain humidity in the crab seedling box.

Fifth, during the transportation process, the humidity of the crab seedlings should be frequently observed, and water should be sprayed with a sprayer at the appropriate time, but it should not be sprayed too much. Too much water will easily cause the bristles and appendages of the crab seedlings to stick to the mesh of the seedling box, causing death. Sixth, during transportation, attention should be paid to climate changes, and attention should be paid to heat preservation, moisture retention, rain protection, wind protection, etc.

5. Why are there yellow crabs among river crabs?

Yellow crabs are river crabs that have not reached sexual maturity, while green crabs are river crabs that have reached sexual maturity. Yellow crabs are relatively small, generally between 100 and 200 grams, with some only 50 grams, and their shells are light yellow. The bristles on the legs (especially the chelipeds) of male crabs are short and sparse, and there are no bristles on the upper and lower sides of the palm of the chelipeds; the abdomen of female crabs is not legged and is triangular. The body of green crabs is larger than that of yellow crabs, and the shell is dark green. The chelipeds and legs of male crabs are strong and powerful, and the hairs on the chelipeds are thick and long; the abdomen of female crabs becomes wider, covering the entire plastron of the head and thorax, and the edges are densely covered with short black hairs.