Business idea - crayfish

Cultivation of crayfish in the pond

After settling pond females with a fertilized eggs with the coming of spring is hatching of larvae, and they grow and develop in a natural environment. This method is the most simple and the most suitable for the breeding of crayfish in the ponds, constructed on the plot. The role of the host is only in how to maintain the water of the necessary conditions (oxygen regime, water hardness, Ph), the ecology of river crayfish, as well as organize their supplemented, if the fodder base of its insufficient.

Mating and spawning. 

In the autumn, when a female leave the larvae and she sheds, the pond is planted males in the ratio of 3:1. Mating season depends on the geographical location of the district. In the North-West region of the mating takes place in October - November, in the Krasnodar krai in December - January, in the delta of the Volga even later. In the period of the mating of crabs are very active, go to the bottom of the pond, get under a plant or go to the shore of the pond even during the day. The outward signs of readiness of males to mate are: swelling and vibration white appendages of the first two pairs of abdominal legs, bent forward, which serve to push the seed weight. Sometimes the genital openings males can be seen projecting out the end of the seminal ducts milky color. For mating need to catch the large males, then the struggle of different sex animals during mating ended in victory for the male, and fertilization of eggs in the female body will happen without serious injury of a female. The fact mating can be identified by the presence of the sexual holes female milky-white body. The yang females that have passed pairing, but did not start to spawning, these masses (first sub-dialects) are saved to moult.
After fertilization, the female is hidden from the male in the hole, and the male fertilizes the one-two and so exhausted that hunger sometimes eats the last female immediately after mating. Therefore, you should choose large males and control the ratio of sexual partners in the population in favour of females. The highest fertility differ females dlinnopaly-logo cancer (table.), which lay, depending on their size, from 50 to 900 eggs and more than a year. The fertility of female shirokopaly cancer lower by approximately 25%. Females with caviar length of 6,5-7,9 occurs only 2.8%, with a length of 9 cm, the percentage of females with caviar comes to 34.7%, with the length of 9.5-59%, and only when the length of 10.5 cm and above all they can participate in the process of reproduction.

Table 

The number of eggs in the female crayfish

Female after mating after about 20 days starting to spawning. Caviar is covered with a substance that hardens in contact with water and attached to the abdominal legs on the threads of this substance. The color just delayed caviar depends on environmental factors, in which live crayfish, but especially from the composition of their food. just delayed caviar has shades of violet-brown to dark-brown color; do not fertilize and the deceased caviar acquires a yellowish color. Mature eggs river cancer is covered with a thin transparent membrane. Yolk consists of a viscous liquid with numerous fat bubbles of different diameter. The weight of the eggs is from 11 to 17 mg, and the diameter of 2.3-3.2 mm. It contains before produce 60,7% moisture and 5.3% of dry substance. Content of protein and calcium salts as well respectively 61,2% and 0.5% to the total mass of eggs.

photo: molto river cancer

During the follow-up eggs, the female moves pseudopodia in the first time is very rare, because the germs in this period is less sensitive to oxygen deficiency. In the later stages of embryonic development they need more oxygen, so it is more energetically working belly legs, spending on these activities 1/3 of the total time. In the period of the maximum photosynthesis (from 12 to 15 hours) often there is a glut in the surface layer of water with oxygen, and it stands out even in the atmosphere. At night, on the contrary, plants consume oxygen and produce carbon dioxide. In addition, oxygen, absorb and other aquatic animals. These factors mainly form the daily mode of oxygen.

Conclusion and growth of larvae of crabs .

At low temperatures, water embryonic development of the fertilized eggs cancers can stay up to 7-8 months. During this period, in the northern part of the amplitude of temperature fluctuations may be up to 20 C and more. This pause in the development of embryos is a biological and practical interest in connection with the possibility of growing larvae of crabs in the basins of-nurseries or aquariums in a more rapid pace, what will be the talk further. Conclusion larvae occurs at temperatures from 18 to 25 C and ends depending on the geographic position in may-June. Developing larvae cancer are very sensitive to the deficit of oxygen in the water, so for its content to keep and maintain with the help of technical means of aeration, especially with the onset of winter, when the pond is covered with ice, with the result that often kills. After the first week of life larvae begin to eat the remnants of eddges shells, point algae, the hyphae of fungi, and two weeks later, eating mainly animal food: dafnia, cyclops, small insect larvae and only in small quantities green plants. However, already in the month of age diet larvae consists mainly of green plants - 63%, planktonic crustaceans - 28,3%, as well as other food - 8,2%.

Young, you can feed the fish and meat minced meat, meat of molluscs, boiled vegetables and potatoes, combined feed for herbivorous fish. Food is better placed in the trough, which lowered into the water in the deep places, and fix it on the vertical riser or some other way. Young mature females spawn not every year, but with the age of their fertility increases, and they are approximately 10 years of age begin to lay their eggs each year. With proper management can be achieved significant increase of their fertility, size and weight, and their longevity increases in connection with the protection of crayfish from enemies, disinfection of water and food during the period of bad harvest of aquatic vegetation. In the natural breeding of crayfish feeding them to start in march - April from the diet in 0.5% of live weight crayfish, increasing the quantity of food in the warm time of the year and decreasing at a low temperature. In a period of growth and moult of the number of food increase up to 2-2,5% of live weight cancer. In the winter period appetite crayfish small, therefore supplemented give at low standards, or it altogether cease. Crawfish - long culture, so when they grow appropriate in the course of 5-6 years after the first settlement annually launch new party of larvae in the pond. Hunting will be possible for a fourth year.

The breeding of crayfish in the ponds in comparison with natural water bodies has a significant advantage. In the ponds, you can establish good monitoring the growth and development of cancers, and in connection with the optimization of the conditions of life of these animals through biotechnology increases the performance of the pool and the fertility of crayfish. In favourable weather conditions and care on the part of the human individual river cancer length of 9.5 cm and a weight of 33.4 g is achieved with two molto (cancers grow only during moulting, as they shed the shell) size of 10.5-10.9 cm and the average weight of a giant city in one of the warm season. Added products under such conditions as compared with the natural reservoirs speak about 54 kg/ha, while unit growth of cancer in 13.4 g. Under average conditions of habitat crayfish and with an annual replanting of gravid females within three years of additional products in the ponds will be approximately 39 kg/ha and with unit growth of the mass of cancer at 9.8 g. All of these examples relate to the ponds of the small sizes (0,3-0,5 hectares), in which the natural breeding and minimum maintenance with moderately developed thickets of aquatic and riparian plants and large usable area (small place from 30 to 60 cm depth) enough food to feed growing cancers.