Fishing methods of crayfish

Crayfish breeding is a relatively good development prospect in the aquatic industry at present. With the continuous improvement of people's living standard in recent years, crayfish is not only popular in the midnight snack world, but now it has gradually become a common dish on the daily dining table. Let's learn about crayfish related information together with Xiao Bian.

How to catch crayfish

Crayfish grow fast, pond breeding crayfish, after 3~5 months of breeding, adult shrimp specifications reach more than 30 grams, can be caught on the market. The young shrimps stocked in March and April can be harvested at the end of May and the beginning of June, concentrated at the end of July, and all harvested in August; the conditions and preparations for rice fields stocked in September and October. The area of paddy field should be large, generally dozens of acres to hundreds of acres. The ridge is high and can hold water depths of 40~60 cm. Ditch with width of 1~ 1.5m and depth of 0.8m shall be excavated along the periphery of the ridge. For larger fields,"cross" or "well" shaped ditch shall be excavated in the middle, with width of 0.5~ 1m and depth of 0.5m. Other preparations are the same as those of the rice field shrimp culture.

Young shrimps can be harvested in March of the second year and can be harvested at the end of May.

Crayfish fishing methods are many, can be used shrimp cage, cage net, hand net, shrimp net and other tools to catch, can also be used fishing rod fishing or pull net catch, finally catch dry pond. From the middle of March to the middle of July, shrimp cage and ground cage net were used to catch shrimp, and the effect was better. Shrimp cages and ground cages have various styles, such as soft ground cages made of useful nets and shrimp cages made of bamboo. It should be noted that before crayfish is caught, drugs should be used with caution for disease prevention and treatment in ponds and rice fields, otherwise the recapture rate of crayfish will be affected. The residue of drugs will also affect the quality of commercial shrimp, resulting in market sales obstacles and affecting breeding benefits.

Life Habits of Crayfish

Crayfish are nocturnal animals and live on the bottom of the camp. It inhabits lakes, rivers, reservoirs, swamps, ponds, ditches, and sometimes rice paddies. However, there are more in still water ditches, ponds and shallow lakes where food is abundant. The habitat is mostly soil, and there are more hidden objects such as aquatic plants, roots or stones. During the day, they often lurk in dark corners, rocks, bushes or caves at the bottom of water bodies, and come out to feed at night. Under natural conditions, due to lack of bait and low transparency of water, it can also be seen foraging during the day. The shrimp has strong climbing ability and burrowing ability.

Under the condition of oxygen deficiency, bait deficiency, pollution and other biological, physiological and chemical factors, it often climbs out of the water surface and enters another water body. When it rains, especially when it rains heavily, the shrimp often climbs out of the water. During the growing season, crayfish rarely dig holes. The longest crayfish burrow can reach 100cm and the diameter can reach 9.2cm. Crayfish can make use of artificial burrows and original burrows and other hidden objects in water, and its burrowing behavior mostly occurs in breeding period. Therefore, proper increase of artificial nests in culture ponds and technical measures can greatly reduce the destructiveness of shrimp to pond ridges and banks.

Introduction to biological characteristics of crayfish

1. Classification and distribution. Crayfish belongs to Arthropod phylum, Crustacea, Decapoda, Crayfish family, Procambarus genus in animal taxonomy, and is called crayfish or Procambarus clarkii. It is a small and medium-sized individual in freshwater crayfish, native to North America, and now widely distributed in more than 20 countries and regions on five continents. The main producing areas of crayfish in China are the middle and lower reaches of the Yangtze River.

2. Morphological characteristics. The whole body of crayfish consists of 20 segments from head, chest and abdomen, 19 pairs of appendages except tail segment without appendages, and the body surface has hard carapace. Sexually mature individuals are dark red or crimson, immature individuals pale brown, tan, reddish brown, sometimes also see blue. Common individuals are 4 - 16 cm long.

3. Food habits. Crayfish are omnivorous animals, feeding mainly on organic detritus. It can feed on all kinds of grains, cakes, vegetables, terrestrial grass, aquatic plants in water, epiphytes, zooplankton, aquatic insects, microbenthos and animal carcasses, and also likes to eat artificial compound feed. At 20~25℃, crayfish ingested 3.2% of its body weight per day, 2.6% of its body weight per day, 1.1% of its body weight per day, 1.2% of its body weight per day, 2.8% of its body weight per day, 4.9% of its body weight per day, and 14.8% of its body weight per day. It can be seen that crayfish like to eat animal substances.

4. Growth and molting. Crayfish, like other crustaceans, must shed their carapace to complete their mutant growth. In Jingmen area, the average length of juvenile prawns separated from their mothers in the middle of September was about 1.0 cm and the average weight was 0.04 g. The average length of juvenile prawns cultured in cages until the end of November was 5.19 cm and the average weight was 4.50 g. The maximum length was 7.4 cm and the weight was 12.24 g. In July of the second year, the average length of the fish was 10.2Cm and the average weight was 34.51g. In ponds with good conditions, young shrimps that have just left their mothers can reach market specifications within 2 to 3 months of growth.

5. Breeding habits. Sex ratio: The ratio of female to male is more than male in the two size groups of body length 3.0~8.0Cm and 8.1~13.5Cm. In the small size group, females accounted for 51.5% of the total, males accounted for 48.5%, and the ratio of females to males was 1.06:1. In the large size group, females accounted for 55.9% and males for 44.1% of the total, and the ratio of females to males was 1.17:1. The reason why females were more than males in large size group was that males were easy to die after mating, and the larger the male individual, the higher the mortality rate.

Crayfish farming precautions

First, people. In the process of raising crayfish, the people who raise crayfish can be said to be "Cheng Xiao He defeated Xiao He". Success lies in human management, and failure also lies in human management. For example, seedling release, water grass management, water quality problems, when releasing seedlings should be gently placed, the shrimp seedlings scattered to let the shrimp seedlings slowly climb away, and some people because of a large number of shrimp seedlings, they directly pour shrimp seedlings on the edge of the pond, shrimp seedlings are piled together, finally lead to hypoxia death, shrimp seedlings lost more than half; In high temperature season, aquatic plants grow rapidly. If they are not "decapitated", they will soon spread to the whole pond, resulting in poor water fluidity. Once the aquatic plants rot, they will also cause the problem of black and smelly water. If the crayfish is not treated in time, the phenomenon of black bottom and death will occur.

Second, climate. After all, crayfish breeding in outer pond still depends on heaven. Climate determines the growth speed of crayfish and affects the incidence of crayfish. Therefore, it can be said that crayfish breeding is "man's plan is in heaven". For example, in June and July of this year, the continuous rainy days and low temperature led to slow growth of crayfish. After August, there were more than 40 consecutive days of high temperature weather. More than half of the crayfish appeared uphill and grassy, and some were found late and not treated in time.

Third, pests and natural enemies. In March, April, July and August of this year, pests occur particularly severely. In serious ponds, the leaves of aquatic plants in the whole pond are eaten up in two or three days. Crayfish lose the shelter of aquatic plants and kill each other when molting, resulting in a high mortality rate when molting. Natural enemies such as rats, snakes and frogs will devour crayfish shrimp larvae.

Fourth, feed quality. The quality of feed determines whether crayfish eat or not and how much feed they eat. High-quality feed crayfish eat vigorously, grow fast, have less disease, feed coefficient is also low, can reduce feed cost.

Fifth, fluctuations. Market fluctuations are divided into two parts, one is the seed price, the other is the commodity shrimp price. In early March and April, the price of shrimp seedlings was between 18- 22 yuan per catty. After this batch of seedlings was put down, they could not be listed until May Day. The shrimp with large seedling specifications could be sold at a good price before May Day, about 28 yuan per catty. After May Day, the price of commercial shrimp dropped all the way, and 13 yuan per catty was sold. Buy seedlings at a high price, sell shrimp at a low price, and the profits from breeding crayfish will be eaten up by more than half.

Although the demand for crayfish was relatively large, its price fluctuated greatly. Therefore, crayfish farming could not be achieved overnight. Only by constantly learning and developing new farming techniques could better quality lobsters be bred.