Breeding crayfish at home. Conditions for growing crayfish for sale in a pond or aquarium

Breeding crayfish at home as a business: where to start?

Breeding crayfish is profitable and interesting activity. In Russia, crayfish meat is popular, and it is not cheap. But few people breed crayfish on an industrial scale. Therefore, small crayfish farms will bring good income to the owners.

The crayfish breeding business has many advantages:

• initial capital - 220 thousand rubles;
• does not require special skills;
• does not take much time;
• brings income from 100 thousand rubles. in year.

Breeding crayfish at home as a business has the following disadvantages:

• seasonality (crayfish reproduce and grow from May to October);
• unforeseen circumstances (death of crayfish due to freezing of water or from infections);
• deferred result (income of 300–400 thousand rubles is possible in the 5th year of creating a crayfish farm).

Crayfish farming business plan

To organize the operation of a large crayfish farm with modern equipment, you need a large start-up capital. But if you start with small volumes, the initial costs will be small.

What is the profit?

In a year, 600 adult crayfish will give rise to 20,000 young (120 kg). They can be left, and then after 2–3 years they will reach a marketable weight of 40–70 g (800–1400 kg), or they can be sold. At average cost juvenile crayfish 250 rubles/kg, you will receive 30 thousand rubles.

If you wait, you can sell large crayfish at a price of 400 rubles/kg, and you will receive 320–560 thousand rubles. in year. While this is not so much, over time the crayfish farm will bring a stable income.

Stages of implementing a crayfish farming business plan

The implementation of a business plan for crayfish breeding includes 5 stages:

1. paperwork;
2. creation and equipping of a reservoir;
3. purchasing crayfish;
4. mastering methods of growing crayfish;
5. sales of products.

Registration of individual entrepreneur

Documents for product sales

1. Sanitary certificate for a vehicle for transporting crayfish. You will get it from your local veterinarian.
2. Declaration of Conformity. It is issued at the local branch of Rosselkhoznadzor.
3. Veterinary certificate form No. 2. It will be issued at the veterinary station or department of Rosselkhoznadzor. To obtain a certificate, you will have to allow representatives of the organization to take a water sample and take a couple of animals for testing.
4. Certification according to GOST R 50380-2005. Issued by the local branch of Rosselkhoznadzor or commercial organizations.

Sample of veterinary certificate form No. 2.

Creation of reservoirs

To create crayfish farms, artificial and natural open reservoirs, pools and aquariums are used.

You can learn how to grow and keep sturgeon at home for sale

Breeding crayfish in artificial reservoirs as a business

The optimal pond area is 30–60 m2, and the depth is 1–3 m. Such a pond can be dug even without the help of an excavator.

Divide the pond into segments or build 3-4 separate ponds, since later you will have to place adult crayfish, females with eggs and young animals in different compartments.

There are a number of requirements for ponds for breeding crayfish:

1. Bottom. Crayfish love to dig holes, so provide a pond with a sandy, clay or muddy bottom. Place stones, pebbles and driftwood there so that the animals have construction material for houses.
2. Temperature. Comfortable temperature for crayfish is 18ºС. In such conditions, animals grow and reproduce quickly. Temperatures below 18ºC will slow growth.
3. The pond should not freeze. In winter, when the reservoir is covered with a crust of ice, crayfish hibernate and stop growing and reproducing. If the water freezes to the bottom, the animals will die. In order for crayfish to survive the winter, in cold regions a deep wintering hole is arranged in the pond, where the crayfish are placed during periods of frost.
4. Water purity. The reservoir for breeding crayfish must contain clean fresh water. Renew it every 2-3 weeks, taking 30% at a time so as not to disturb the established microclimate of the pond. You can supply water to the reservoir and arrange a drain so that the water can flow.
5. Shadow. Crayfish do not tolerate water heated by the sun, so plant spreading willows along the edge of the pond. They will protect animals from sunlight.
6. Crayfish planting density. Do not place more than 8 animals per 1 m2, as they are prone to fights and cannibalism.

Crayfish Care

Crayfish do not require much attention, but a novice owner of a crayfish farm should know the characteristics of his charges.

Water

Water indicators:

• oxygen saturation – 5–7 mg per 1 liter of water;
• hydrogen saturation – 7–9 mg per 1 liter of water;
• presence of silicon and calcium;
• water exchange rate – 50 l/min per 1 thousand m2.

Reproduction

The female lays up to 100 eggs in 1 year, but survives best case scenario, 60 larvae. To get a self-replicating herd of crayfish, you will have to wait 5 years.

Cancers are prone to cannibalism. Therefore, it is not worth keeping adult crayfish and young ones in the same pond. In the spring, remove females with eggs from the general herd. Send the larvae to a heated pond: for development they need a temperature above 23ºC.

At proper care in 2 years, crayfish grow to 10–12 cm in length and weigh 50–60 g. But do not sell all the grown young animals. To ensure the herd reproduces itself, catch only 20% of the animals.

Feeding

The daily food intake for an adult crayfish is 2–5% of her body weight. If there is not enough food, the crayfish fight, damaging each other’s shells and tearing off their claws, and lose their marketable appearance. If there is too much food, the leftovers pollute the pond.

Crayfish are omnivores, so they are fed:

• pieces of meat and fish;
• potatoes and vegetables;
• aquatic plants;
• worms, larvae and plankton;
• steamed crushed grain;
• special feedstuffs.

In the morning and evening, place food in grid feeders (width - 1.5 m2) so that its remains do not pollute the pond.

If crayfish live in aquariums, more food is required. If animals live in an artificial open reservoir, they get part of their food on their own.

Marketing of crayfish

Take care of sales in advance, even before creating a farm. Usually there are no problems with the sale of goods: shops and restaurants are happy to purchase quality products.

They sell crayfish:

• restaurants;
• cafe;
• supermarkets;
• beer bars;
• shops.

Experienced businessmen advise where you will exhibit your products.

Despite the obvious benefits, few people breed crayfish. There are still few competitors in this area. Therefore, if you open a crayfish farm, rest assured that in a few years your costs will more than pay off.

Breeding crayfish at home as a business - what do you need to know? Watch the next video lesson:

Crayfish in a country pond

Breeding crayfish in the country has recently become fashionable. Not every summer resident can do this, but if you have the desire, it’s worth a try. What do you need to know and be able to do for this? Know: structure, life cycle and ecology of crustaceans. Be able to: support the necessary conditions in a pond.

The shell-clad body and 19 pairs of limbs indicate the ancient origin of these arthropods. Ancient crayfish reached more than a meter in length, and their modern descendants - lobsters, scorpions and well-known freshwater crayfish - are significantly inferior to them in size, although they are similar in appearance. Despite their formidable appearance, crayfish are peaceful animals that consume plants and dead animals as food; they are orderlies of reservoirs.

The chitin-calcium shell inherited from ancient ancestors cannot increase as the cancer grows, so it has to be discarded. A molting crayfish sheds not only its outer case, but also the membrane of its gills, eyes, and even the esophagus. Of all the solid parts of the body, cancer retains only the white calcium formations located in the walls of the stomach - gastroliths. In the Middle Ages, they were called “crawfish stones” and were considered a miracle cure, but in fact, gastroliths are a depot of calcium, which after molting is used to recreate the shell and other solid organs. Crayfish molt 8 times in the first year of life, 5 times in the second year, and then 1-2 times a year. Molting is especially dangerous for juveniles - the soft-bodied crustacean becomes easy prey for any predator. Adult crayfish also do not always molt successfully; it happens that a claw gets stuck in the old shell, then the crayfish tears it off in order to free itself (but like many other arthropods, crayfish are able to regenerate lost limbs).

Crayfish mate in the fall, then the females lay 100-300 eggs, which they carry under their abdomen all winter and spring, washing them with water using swimming legs. The offspring hatch in June/July. Small crustaceans first hang motionless on the female’s legs, after the first molt they try to get away from her (but if there is danger, they hide under her abdomen), and after the second molt they move on to independent existence.

Crayfish lead a solitary lifestyle; they vigilantly guard their shelters under stones or snags with their claws out. Therefore, in the breeding pond it is necessary to equip a sufficient number of nooks and add wood material (fragments of branches, roots) to construct shelters. In search of food, crayfish leave their shelters late in the evening, “graze” all night and return home early in the morning, before sunrise. They do not go far from shelters, especially females and old males. In late autumn, crayfish go to deep places in the reservoir. Crayfish are not afraid of long periods without water.

In recent years, pollution of water bodies and (as a consequence) an increase in epidemics among crayfish populations in the rivers and lakes of Europe have led to a sharp reduction in their numbers. The species that suffered the most was the broad-toed crayfish (with a smooth, spineless shell and a bright ruby-colored body and claws), which has been fished for a long time. Therefore it is better without depleting Natural resources, start breeding crayfish in a pond.

The native species of crayfish suitable for breeding are the northern broad-toed crayfish and the southern long-toed crayfish. Currently, biotechnology is being developed for the artificial breeding of signal crayfish (introduced species) with white spots on the claws with a blue border. Signal crayfish does not suffer from crayfish plague and grows quickly. When growing juvenile crayfish, I recommend using technology accelerated development, when the time of embryonic diapause is reduced by temperature exposure. As a result, the crustaceans hatch in early spring and by autumn they become much larger and more viable.

Crayfish farming can be done from May to October, as long as the water in the reservoirs does not freeze. First of all, you need to dig at least three reservoirs on the site. The soil must have low permeability to avoid water loss due to seepage. Areas with meadow soils and weakly permeable soils (clay, loam) are best suited. Sandy soils can be used to construct a pond, strengthening dams, slopes and its bed plastic film, and the film should be covered with soil on top. The size of one reservoir is 5x10 m, shallow, the bottom is sandy, with rocky shelters, in the coastal part you can plant aquatic plants. Running water is brought to the dug hole and a drain is arranged, fenced with a fine-mesh strong mesh.

Naturally, much will be determined by the size of your plot, but Special attention You need to pay attention to the layout of the pond bed, good water supply and the possibility of complete water discharge. It would be ideal if a stream flows through the site, then the reservoir is provided with running water, and several reservoirs in a row can be made along the path of the stream. When breeding crayfish, it is necessary to carefully monitor water quality. Water analysis can be done at any sanitary-epidemiological station or in an agrochemical laboratory. Water must be free from various impurities, have no foreign odors, tastes or colors. The presence of free chlorine, hydrogen sulfide and methane in the water is unacceptable (these substances can cause death or an outbreak of disease).

Breeding crayfish are placed in ponds, and food is placed on special wooden trays. You can feed crayfish with pieces of meat, fish, and potatoes. After several months, the crayfish will begin to reproduce; one pair of crayfish can produce about 30 young crayfish per year. It takes 3-5 years from the egg stage of a broad-clawed crayfish to its commercial size; narrow-clawed crayfish grow faster. The first stage larvae emerge in May-June; they can be reared in the same pond or transplanted into another. Yearling crayfish are caught and transplanted into feeding ponds, where the stocking density is lower.

Well-developed crayfish are eaten, mainly as a snack for beer. They are boiled in boiling water, adding salt, dill, and pepper. It is necessary to cook the crayfish over high heat, maintaining it so throughout the cooking process. Cooking time, as a rule, is up to 25 minutes, and readiness is indicated by the bright redness of the shell. In any case, there is no need to skimp on salt, because the cancer is covered with a shell and therefore does not absorb salt well. Dill can be placed in the pot in the form of seeds or roots; it gives crayfish meat a special piquancy in taste. If spices are not used or used in insufficient quantities, then crayfish meat may seem tasteless to you. To enhance the flavor, it’s a good idea to add spices such as a couple of onions, cut into halves, currant or cherry leaves while cooking the crayfish. They can also be boiled in beer, cucumber pickle, milk and wine.

A. Lenshin, assistant

Departments of St. Petersburg State University

Newspaper "GARDENER" No. 54, 2010.

One of the rather interesting and profitable types of business is crayfish farming. Moreover, it is not carried out by large farms, but, as a rule, by small household enterprises. With all the favorable conditions created for the reproduction, growth of crayfish and their further sale, you can not only recoup your costs in a season, but also remain in good plus. You can make very good money from such an interesting and profitable business. In this article, we will look at some of the basics and components of the process.

First, you need to realize that the organization itself, which requires a divorce in monetary terms, will be about 200,000 rubles. It is worth immediately noting that this is the maximum amount for the proper design of the habitat and maintenance of these animals.

The initial stage will be digging a pit for the pond and further arranging it if a ready-made one is not available. Having dug a pit, which, by the way, should preferably occupy an area of ​​30-60 sq.m. (more is possible) and have a depth of 1-3 (up to 6) meters, you need to proceed to the direct arrangement of the relief of its shore and bottom. It is better to cover the latter with stone and lightly sprinkle it with river sand, which will improve the conditions for feeding, mating and general habitat of crayfish. Breeding crayfish in a pond also requires clay or similar banks. This is necessary for animals to build burrows and reproduce. As an alternative to clay, hollow brick can be used as a bank edge, with holes ready for holes. It is preferable to have not one, but several (3-4) crayfish ponds, insuring yourself from the possible consequences of climatic or any other factors, as well as for economic reasons.

Breeding crayfish also requires directly releasing their individuals into the pond for further reproduction. For one described reservoir, about 150-200 specimens are required. The main thing is to choose good individuals for breeding. It is also worth considering that in one season a male crayfish can fertilize up to 4 females. The latter produce a lot of eggs, but from a favorable brood of one female about 30 young crayfish emerge. So we have that the estimated increase in the crayfish family in the pond is, according to conservative estimates, more than 4,500 per year (based on 160 females and 40 males). Thus, industrial is quite productive.

Having understood the arrangement of the habitat, you need to keep in mind some more important details this business. We must not forget that breeding crayfish still requires some care for the reservoir and proper feeding of the arthropods. As for water care: it is necessary to change about 20-30% of it after 2-3 weeks. Such a small percentage of replacement is due to the fact that the microclimate of the reservoir is very vulnerable, and changing a significant amount of water leads to disruption of the crayfish’s living conditions, and therefore to their death.

Selecting the diet of crayfish will not be particularly difficult, but it must be regular (once every two days) in order to prevent crayfish cannibalism, which is not uncommon among these arthropods. Under favorable conditions and abundant nutrition, the crayfish reaches marketable size in 3-5 years. It is preferable to feed them directly; it is cheap and does not lead to pond clogging. But meat, bread, larvae, fish, etc. can be used as food for crayfish.

Regarding the period of cancer reproduction, this is approximately February-March or October-November, depending on the latitude of the reservoir, climatic and other natural conditions.

Thus, crayfish farming is a very profitable business. But it is worth taking care in advance about marketing the products and collecting the necessary permits (if any are required) from the competent authorities.

Anyone who has tried crayfish meat at least once knows how tasty and tender it is. Currently, the breeding of these representatives of the fauna in Russia is practically not developed. However, demand for the product is high. Some villagers manage to make good money from crayfish fishing in their natural environment habitat, but in this way they negatively affect the natural population of these animals. Such fishing is essentially poaching. Even before the revolution, Russia was successfully breeding crayfish in an artificial environment. The resulting meat was exported to many European countries. The current state of affairs is such that the main suppliers of this product to the world market are Turkey, China and Spain, countries where previously crayfish were not found at all.

Pond

How to breed crayfish in ponds? To begin with, if it is silted or swampy. The proximity of crayfish to crucian carp, carp and other non-predatory fish is allowed. However, keep in mind that such businesses will suffer when winter comes. This is explained by the fact that crayfish tend to hibernate if the air temperature drops below fifteen degrees Celsius. In a state of suspended animation, they stop consuming food and, accordingly, do not gain weight. If the pond completely freezes to the bottom, your pets will die.

However, many businessmen are wondering how to breed crayfish in ponds, because such reservoirs are the most sustainable aquatic systems, capable of self-purification and self-renewal. At the same time, there is an opportunity to save a lot on feed, filters and aerators. Crayfish will happily feed on plankton, algae and insect larvae. The disadvantage is that in the natural environment these animals do not grow fast enough. The commercial mass is gained approximately in the fifth year of life. Thus, the business will begin to generate income only after six years. The attractive thing is that there is virtually no initial investment required.

Aquarium

How To do this, you will need an aquarium with a capacity of at least two hundred and fifty liters (frameless). Pour soil into the bottom of the container, and also place stones and driftwood there (your pets will hide behind them).

How to breed crayfish at home so that they do not hibernate? To do this, it is important to ensure that the water temperature fluctuates insignificantly and does not fall below fifteen degrees Celsius. In addition, it is important to ensure high-quality filtration and aeration of the liquid. Under such conditions, it is allowed to increase the stocking density of animals to three hundred and fifty individuals per square meter.

The only drawback of the described business is its small volumes. Industrial scale is difficult to achieve due to the limited cultivation area. However, some entrepreneurs have figured out how to breed crayfish in an aquarium in order to get maximum profit. At home, they raise the larvae to “fingerlings,” and only then release them into a natural or artificial reservoir. Thanks to this solution, it is possible to organize successful business. But how to breed crayfish at home to minimize losses? Control over water quality should come first. In this case, not very many larvae will die, in addition, they will develop much faster.

Basement

How to breed crayfish at home if you don’t want to clutter up your living space with huge aquariums? Use your basement. For most people, it plays the role of a place to store unnecessary things, but for you it will become a way to get money. If necessary, you will need to insulate the basement to prevent the crayfish from hibernating at low water temperatures. To organize lighting, purchase a lamp with a power of two hundred watts and hang it in the center of the ceiling. Equip your basement with multi-tiered shelving to accommodate aquariums. After finishing preparatory work the time will come to ask the question of how to breed crayfish.

Where to buy

Buying larvae is not easy. Most likely, you will have to raise the young animals yourself. You can even buy crayfish at the supermarket. For every male there should be two females. In autumn, mating time begins. At the end of spring, females can be easily visually distinguished from males by the presence of eggs under the tail. A kilogram of these animals can cost you from three hundred to five hundred rubles. And even such small expenses can be avoided by catching crayfish yourself in the pond.

What to feed

How to properly breed crayfish so that they actively gain weight? To do this, it is important to provide them with high-quality, nutritious nutrition. Crayfish prefer earthworms, insect larvae and small snails. In an artificial habitat, they will not refuse steamed and crushed grains, boiled potatoes and grated carrots. These products should make up the majority of the animals' diet. Meat and fish are valuable sources of protein. How to breed crayfish without making mistakes in the process of feeding them? Calculate the daily food intake of animals. It should be 2% of their weight.

Features of reproduction

Mating occurs in September and October. Males are able to fertilize up to two females in a row. If they come across a third one, they will simply eat it. This fact determines the optimal ratio of individuals of different sexes in the reservoir (two females for one male).

Initially, the eggs are located under the animal's shell. Once laid, it is secured under the tail. In order for the embryos to develop properly, the female constantly washes the eggs, thereby effectively cleaning them. After two months, the larvae hatch. For another three weeks they rest under the female’s tail to avoid many dangers. After this time, completely independent crustaceans leave their cozy shelter forever. In their natural habitat, each female is capable of raising up to twelve larvae. She cannot have more than twenty descendants a year. As for home conditions, this number can actually be tripled.

Shedding

Young crustaceans molt eight times in the first twelve months of their lives. They will have to go through this up to seven to nine more times over the next two years. Adults molt much less frequently - once or twice every 12 months. During this period, the old shell is simply discarded, as it becomes too small for the growing animal.

How to breed crayfish correctly? It is necessary to pay special attention to them during the molting period, when the animal becomes especially vulnerable to attack not only by predatory fish and birds, but also by its relatives.

Diseases

Breeding sites

If you are serious and plan to turn crayfish farming into a highly profitable business, we recommend organizing a farm. Only in this case will it be possible to establish the production of a tasty product on an industrial scale. To do this you will need the following:

- Incubation aquariums. It is very important that they are equipped with powerful heaters, compressors and a filtration system.

- Pools where crayfish are bred and have become independent individuals. There they need to be raised to the fingerling stage.

- Indoor ponds. There should be at least two, but it’s better to try to organize even more. This way the business will develop faster. The minimum area of ​​the reservoir should be 25 square meters. m, and the depth is 2 m. Keep in mind that gas exchange occurs better in elongated ponds. It is recommended that they have running water. That is why it is so important to have a river flowing nearby. If this is not possible on your farm, drill several water wells.

Be sure to place shelters for crayfish at the bottom of reservoirs. They can be fragments of plastic or ceramic pipes, stones, driftwood, etc.

Important point

What kind of crayfish is best to breed? In Russia, the most common species are Far Eastern and European. The latter are most often used on an industrial scale. They are divided into long-fingered and broad-fingered. The latter are the most valuable species. It is their abdomens that are called “crayfish necks” in cooking. However, keep in mind that this type is listed in the Red Book, so it is still better to breed long-toed crayfish. This way you will avoid problems with inspection authorities.

Lake and river crayfish are also distinguished. The first ones are most suitable for home business, because they do not hibernate and can reach impressive sizes. However, there is one drawback: lake crayfish are very capricious. To breed and successfully maintain them, you will need a warm room with an area of ​​at least twenty square meters. Crayfish are not so demanding, but they are smaller in size, and accordingly, they are not so expensive.

When purchasing animals, do not lose sight of the fact that crayfish of different species do not live in the same body of water.

A dacha is not only for garden beds

Arranging a pond on personal plot, keep in mind that it is very important for crayfish to have holes. That is why the pond should have clay banks and a rocky bottom. It is very important that it is located on your territory, then you will be able to control the breeding process and protect the animals from criminal attacks.

How to breed crayfish in the country? If the area is large enough, it is better to organize three or four reservoirs. Of course, you can do it yourself, but an excavator can handle such work much easier. Spare no expense and order the necessary equipment. After completing this stage of work, think about landscaping the reservoirs. It is better to cover the bottom with stones and sprinkle them with river sand. Plant grass (field or garden) along the edge of the pond.

Next, proceed to organizing drainage. To do this, you can use a regular pipe, which is closed on top with a valve. Put a net on the pipe so that the crayfish do not have the opportunity to leave the reservoir through a kind of tunnel.

The most exciting moment is filling the pit with water and launching the first crayfish. Now comes a period of constant concern for the habitat of animals. Remember to change the water every two to three weeks. It is better to renew the pond by about a third, so as not to greatly disturb the established microclimate.

Is it profitable to breed crayfish?

To obtain at least one ton of these animals over several years, you will need to purchase about six hundred individuals. The main costs occur during the start-up period. They amount to approximately 120 thousand rubles. for equipment of reservoirs and 50 thousand rubles. for the purchase of young animals. If you invest two hundred thousand rubles, you will earn your first million in about two years. Of course, these are just rough estimates. In fact, income depends on sales prices. In addition, keep in mind that the larger the crayfish, the more expensive they are.

How to sell?

The absence of problems with points of sale is one of the main advantages of this business. The fact is that currently competition in this area is low, and this is despite a constant shortage of crayfish. Numerous restaurants, cafes and bars may be interested in your product. As a rule, they prefer wholesale suppliers.

Did you know that salted crayfish caviar is almost as good as red caviar in taste and nutritional quality? This can also be emphasized in the process of searching for buyers. Besides, in various types In production, the chitinous shells of the animals considered, amazing in their properties, are widely used.

Conclusion

We examined in detail the question of how to breed crayfish. This business is profitable, but don't expect instant profits. Proper organization of the habitat and careful care of crayfish is the key to success.

Crayfish are invertebrate animals. They are in great demand throughout Russia. Natural populations of crayfish are decreasing every year due to poaching and disease. Natural reserves of crayfish reach their maximum every eight years, after which they decrease to a minimum.

Currently, much attention is paid to crayfish breeding in artificial reservoirs. In terms of per capita consumption, Greece and Italy lead. Crayfish were brought to these countries from the former Soviet Union. Every year, these countries supply up to 11 thousand tons of commercial crayfish to the foreign market. Spain, Portugal and China also supply crayfish.

In country and homestead ponds, you can successfully breed fast-growing species of crayfish, such as broad-toed and long-toed. Common crayfish live in rivers, lakes, ponds, floodplains, streams with clean soft water, on clay, sandy, peaty, but not rocky bottoms. Favorable temperature water for cancer is not lower than 12 degrees Celsius. The depth of the reservoir is from 1.5 to 6 - 15 m. The best habitat for crayfish is the shoreline of the reservoir with inlets, where aquatic vegetation grows well.

When eating vegetation, calcium metabolism in the body of crayfish accelerates, which contributes to the hardening of the shell after molting. On a small dam near a river, the soil near the shore should be such that it is convenient for crayfish to build holes. In addition to burrows, crayfish can be found under stones, stumps and roots.

Typically, crayfish make burrows on steep, shady banks where there is little sun. Reeds, willows, acacias, and willows can grow on the banks. Burrows can be of the following sizes: length 10–40 cm, width 5–20 cm, height 3–18 cm. In winter, crayfish burrows are located at the very bottom of the reservoir, in summer - closer to the shore, depending on the temperature.

Crayfish dig burrows using their legs and tail, supported by their front claws. Crayfish need tails not only for digging holes, but also for swimming. They swim backwards and at the same time hit the water with their tail. Crayfish, as a rule, do not live in acidic water. The optimal amount of oxygen dissolved in water for crayfish is 7–8 mg/l. A short-term reduction to a level of 2–4 mg/l is possible.

Typically, crayfish are nocturnal, but if they smell prey, they will strive for it during the day. They feed on shells, slugs, insect larvae, worms, carrion that is not very rotten, young stems of reeds, water lilies and other plants. Crayfish especially readily eat algae rich in lime, which, like the peel of shells and slugs, is used to form a shell. The shell consists of chitin - 46.73%, calcium carbonate - 46.25%, calcium phosphate 7.02%.

Female crayfish always sit alone in burrows, while males often gather in groups during wintering. Crayfish are dioecious animals. Males of long-clawed crayfish reach sexual maturity in the third year with a body length of at least 7–9 cm, and females in the fourth year with a body length of 6–7 cm. Some males are 2–3 times larger than females. The surest signs of difference are the genitals lying on the thoracic side, at the border of the chest and tail. In the male, the paired openings of the gonads are located at the base of the last pair of legs, in the female they are located at the third pair from the end. Already in September, in the female’s ovary, from 100 to 300 yellowish testicles are formed; at the same time, the male’s sperm ducts begin to greatly increase, looking like two thick white intertwined threads.

Mating occurs in October–November or February–March. In terms of timing, a lot depends on the region. Mating duration is from 15 to 20 days. Fertilization occurs inside the body. A male can fertilize up to four females in a row. After mating, the female retires to her burrow and 20–25 days after mating begins spawning, releasing eggs through the genital openings. The number of eggs in the broad-fingered species of female crayfish, from 7 to 8 cm long, reaches 68 pieces, and in the long-fingered crayfish - 60 pieces. In the broad-fingered species of female crayfish, from 8 to 9 cm long, the number of eggs reaches 93 pieces, in the long-fingered crayfish - 102; in the broad-fingered species of female crayfish from 9 to 10 cm long - 163 pieces, in the long-fingered species - 174. In the broad-fingered species of female crayfish from 11 to 12 cm in length - 302 pieces, in the long-fingered species - 350 pieces. In the broad-fingered species, female crayfish from 13 to 14 cm long have 425 pieces, in the long-fingered species there are 500 pieces.

The eggs quickly stick under the abdomen to the spoonpods and remain there until the larvae hatch. Since the eggs must be continuously washed with water enriched with oxygen, the female drives the water with a splash, bending and unbending the end of her tail. Calm water, if the female sits in a hole, stagnates, becomes depleted of oxygen and the eggs die.

Crayfish eggs can be easily damaged by water scorpions, swimming beetles, and smooth beetles. The female constantly washes the eggs from dirt, mold and algae. A female crayfish can have from 120 to 500 eggs. The hatching time of crayfish offspring depends on the weather and region. As a rule, hatching occurs at the beginning or in the second half of summer.

Externally, crayfish larvae differ little from adults, except for size. The length of one-day larvae reaches 9–16 mm. At first, they remain attached under the female’s abdomen and hold onto the mother’s leg-shaped appendages with their claws. After 10–12 days they begin to swim near the female, but in case of any danger they hide under the abdomen. After 45 days, the larvae leave the female forever. In the first summer they change their shell 7–8 times, in the second summer - 5 times, in the third and subsequent years the male 2 times, the female 1 time. This exchange occurs in a period of time from 10 minutes to several hours.

They grow slowly. By autumn they reach 3–3.5 cm in length. By the end of the second year of life, young crayfish grow to 7–9 cm, at the age of three years – 10–12 cm; By the age of five, the cancer can reach 12–15 cm in length; by the age of 20, large specimens reach 20–25 cm in length. At the age of 8–10 years, crayfish reach a length of 10–11 cm or more.

Juveniles raised in rivers and lakes reach commercial size in the third or fourth summer. In ponds, two-year-old crayfish during the warm season reach a fishing length of 10 cm and a weight of 32 g. Some crayfish with a size of 12.3 cm reach 70.5 g of weight or more. The survival rate of fingerlings in ponds with a good food supply during the growing season is much higher (85–90%) than in natural reservoirs (10–15%). The high growth rate and survival rate of juveniles is explained by the good food and temperature conditions that they find in artificial reservoirs. In rivers, juveniles do not receive even the minimum diet that covers energy expenditures for searching for food and metabolism in the body.

Under natural conditions, the sexual maturity of crayfish occurs in the third year of life with a minimum size of females of 6–7 cm. A 10-centimeter crayfish of four years old can be considered already a breeder. The timing of mating depends on the conditions in the reservoir and water temperature. In some regions this occurs in March - April at a water temperature of 8 - 12 degrees Celsius. Larvae hatch from eggs in the second half of May - the first half of June at a water temperature of 21–24 degrees. The larvae begin to live independently in such conditions 10–14 days after hatching.

Under natural conditions, crayfish go through the following stages of development. First stage: development duration is from 1 to 7 days, larval size is 1.5–2 mm; second stage: duration of development from 5 to 8 days, larval size 8.7 mm, weight 14.7 mg; third stage: development duration from 9 to 14 days, larval size 1.2 cm, weight 34.7 mg; fingerlings: development duration up to 90 days, larval size 3 cm, weight from 8 to 19 g; two-year-olds: larval size 6 cm, weight 32 g; sexually mature: development duration is three years, larval size is 6.7 cm; sexually mature: development duration 10 years, larval size 9 – 10 cm, weight – 50 g.

Depending on the age, crayfish have the following dependence in size: at the age of 20 days, the length of the male reaches 21.9 mm, the length of the female – 21.6 mm; at the age of 30 days, the length of the male is 28.5 mm, the female is 28.0 mm; at the age of 40 days, the length of the male is 34.7 mm, the female is 33.87 mm; at the age of 50 days, the length of the male is 40.2 mm, the female is 39.3 mm; at the age of 60 days, the length of the male reaches 45.3 mm, the female – 44.2 mm; at the age of 70 days, the length of the male is 49.9 mm, the female is 48.6 mm; at the age of 80 days, the length of the male is 54.0 mm, the female is 52.5 mm; at the age of 90 days, the length of the male is 57.7 mm, the female is 56.0 mm; at the age of 100 days, the length of the male is 60.7 mm, female – 59.0 mm; at the age of 110 days, the length of the male is 63.3 mm, the female is 61.5 mm; at the age of 120 days, the length of the male reaches 65.4 mm, females 63.4 mm.

Some methods of breeding crayfish

Since the testicles come out already fertilized, the main concern must be focused on the female carrying the testicles, placing her in safe room, where you can feed her until the young crayfish fall away from her. Small crayfish should be fed until autumn in pools or small flowing ponds with steep banks and a dense bottom, into which water is carried through pipes with a diameter of 20–25 cm.

There are various practices for raising crayfish. In some farms, crayfish are grown in wooden waterproof boxes made from 5-centimeter boards. The length of the box is 12–15 m, width 6 m, depth 1.2 m. The manufactured boxes are placed on the bottom of a dry pond. Water is carried into the pond through pipes with taps and outlet pipes. Small cells with a volume of 5 cubic meters and several floors are arranged along the walls of this pool. The cells are placed one above the other so that the walls of the pool form their back wall, and in front the cell should be open so that the crayfish can freely enter and exit it. Each cancer has its own cell.

Then stones and stumps are piled on the bottom of the pond so that the crayfish can hide under them. In two corners of the pond, small mounds of rich, marl clay are poured with a layer of 90 cm in height and planted with reeds, watercress and other plants. After installation, the pool is filled with water and more than a thousand females with fertilized eggs are placed in it. Crayfish are fed with scraps of finely chopped meat, young frogs, fish meat, etc. The water is coming DC a jet 25 cm thick and leaves through an outlet pipe protected by a mesh with small cells. In mid-October there may already be more than 20 thousand crayfish. Young crayfish are left until they grow a strong shell.

Under natural conditions, it is rare to find a female with more than 20 crustaceans on her tail, and some of these twenty themselves fall off prematurely, others die, so on average each female raises no more than 12 crustaceans per year. When breeding in reservoirs - pools, you can get from 35 to 65 crayfish from each female.

To remove juveniles from females, you can use the following method. Shortly before the crayfish hatch from the eggs, the females are placed in a large pond, divided into two floors by nets. The upper mesh has quite large cells; after falling away from the mother, the crustaceans will fall through them to the lower floor, where there is a second mesh with very small cells. On it, crustaceans receive the necessary food and protection from enemies.

Crayfish are very picky about water, and it often happens that they begin to crawl out of the water immediately after they are placed in a pond, lake or other body of water that looks quite suitable for their breeding. In such cases, you should keep them for several days or weeks in a basket, circle, top, lowered into water, and feed them there. If after this they are released into the wild, they immediately begin to look for places in the water where they can hide and no longer try not to get out of the water. In ponds with clean water, abundant vegetation and low water flow, artificial feeding can achieve rapid cultivation of crayfish.

In order to increase crayfish stocks and the cancer productivity of reservoirs in ponds and other natural reservoirs, it is necessary to conduct proper management, which involves carrying out biotechnical measures in rivers and reservoirs and artificial breeding of crayfish in ponds. In pond crayfish farming, crayfish productivity is understood as the increase in crayfish per unit area during the growing season.

To determine the value of the crayfish productivity of ponds, it is necessary to subtract their planting weight from the weight of the grown and caught number of crayfish (per unit area). The annual increase obtained in a pond per unit area due to natural food is called natural cancer productivity, and the increase due to natural food and feed introduced into the pond for feeding crayfish is called total cancer productivity. In natural reservoirs, crayfish productivity refers to production, that is, the catch of crayfish per year per unit area.

The catch of crayfish obtained from natural food found in water bodies depends on the availability of food and the degree of its use. The formation and development of food in reservoirs depends on environmental conditions that contribute to the intensity of life processes. As a result of complex biological processes At the bottom of the reservoir, the organic matter of sludge is destroyed by microorganisms, the oxidized elements of the ash part of the sludge are released, the water is enriched with mineral salts and the creation of primary products - phytoplankton and bacteria that absorb a solution of mineral salts and organic compounds from the water. Subsequently, the development of zooplankton and benthos occurs, feeding on primary products (phytoplankton and bacteria), necessary for the development and growth of crayfish.

Thus, cancer production is created as a result of the biological cycle of substances, and the amount of natural cancer production depends on the intensity of life processes that determine this cycle.

Food supply of reservoirs

Lower unicellular algae and bacteria that develop in the water column are united under the general name - plant plankton (phytoplankton). Algae reproduce by division very quickly. After three days, their number increases fivefold. Algae are used as food by lower aquatic animals - zooplankton, which inhabit the water column, most of which die and fall to the bottom.

Dead algae are partially used by organisms inhabiting the bottom of the reservoir (benthos), and most of it accumulates in the form of organic residues. Bacteria that develop in water reproduce even faster than algae. In 15 hours, one bacterium can produce 1 billion offspring. Some of the living bacteria, together with living algae, are consumed by zooplankton. A significant number of them die, decompose, mineralize and re-enter the biological cycle.

If there is enough oxygen in the water, organic matter decomposes quite quickly as a result of bacterial activity. In this case, carbon and hydrogen turn into carbon dioxide and water, nitrogen from protein compounds turns into urea and ammonia. Then, under the influence of nitrifying bacteria, nitrate nitrogen is created, which is well absorbed by green algae. The development of life processes in ponds creates good conditions for protein synthesis in the body of crayfish.

In addition to carbon, hydrogen, oxygen and nitrogen, the protein substances of crayfish include phosphorus, sulfur and iron (blood hemoglobin). The bones of crayfish are rich in calcium. Calculations and chemical tests waters show that the annual increase in crayfish contains significantly more nitrogen and phosphorus than in the water of ponds, which is explained by the biological cycle of substances occurring as a result of the development of life processes in ponds. The biological cycle occurs as a result of different life expectancies of organisms and reproductive abilities.

The fast and intense life process in ponds contributes to the intensive development of organisms used by crayfish as food. However, the amount of certain salts in water does not yet determine the intensity of life processes and the amount of cancer productivity. The amount of certain mineral salts present in the soil is no less important. Water leaches mineral salts from the soil, dissolving them, thereby preparing food for lower algae. Organic matter in the soil is used by bacteria and ciliates for nutrition.

Ponds built on chernozem soils have the highest cancer productivity. Ponds with loamy, clayey and sandy soils are less productive. Mineral salts and soil organic matter have great importance only in the first years after the formation of the reservoir. Then, as it ages, this value is lost. In old ponds, the role of the soil in replenishing nutrients is played by pond silt, which accumulates at the bottom. Organic substances of pond sludge containing protein, under the influence of microorganisms, enter into the cycle and provide food for phytoplankton. The cancer productivity of the pond depends on the intensity of the work of bacteria supplying nitrogen and phosphorus to the water. Nitrogen promotes the growth of plants and animals, and phosphorus promotes the growth and acceleration of decomposition processes in plant organisms, as well as the development of reproductive products in animal organisms.

Nitrogen compounds are deposited in pond mud and serve as fertilizer for underwater and above-water plants. Some of the nitrogen contained in living organisms consumed by crayfish also falls out of the cycle. The amount of nitrogen in the ponds is replenished annually. It comes with water runoff from drainage areas in the form of mineral salts and undecomposed organic residues. An indirect indicator of the amount of organic substances in water is its oxidability. The degree of oxidation is determined by the amount of oxygen absorbed by one liter of water to oxidize the organic substances contained in it. If oxidation is low, this indicates that the water is poor in nutrients for the development of phytoplankton.

For pond farms, water is considered good if its oxidability does not exceed 20 mg 02/l. If the oxidation of water is more than 20 mg 02/l, this indicates contamination of the water supply source. Such water is unsuitable for breeding crayfish.

Phosphorus, determined in combination with oxygen, is the most important biogenic substance. It is consumed by plant organisms along with nitrogen and is part of plant protein, digestible by animal organisms. Phosphorus is contained in water in the form of phosphoric acid salts and organic compounds. The main source of phosphorus replenishment in ponds is water runoff from fertilized fields in the catchment area. Phosphorus absorbed by crayfish is carried away from the reservoir and excluded from the cycle. Ordinary, unpolluted sources contain up to 0.5 mg/l of phosphorus. For intensive development of green algae, 0.2 mg of phosphorus/l is sufficient.

High productivity of crayfish breeding can be achieved if the nutrients in the pond are used by beneficial consumers. Of the lower algae that are part of the phytoplanton, beneficial consumers include microscopic protococcal green algae, mainly chlorella and scenedesmus. Blue-green algae consume nutrient salts and play a negative role. They are not used as food by zooplankton and are almost never eaten by crayfish.

Secondary production in the reservoir consists of zooplankton and benthos. Zooplankton includes ciliates, rotifers, copepods and cladocerans. Ciliates develop mainly in the coastal zone of ponds and serve as food for crayfish only in the first days after the larvae hatch from the eggs.

Copepods found in ponds are very valuable for crayfish breeding. They reproduce in large numbers at all times of the year, especially in early spring, when crayfish, exhausted after winter, begin to feed. Cladocerans are also fertile. This group includes daphnia, bosmina, polyuphemus, etc. The most valuable among the cladocerans are daphnia and moinae, which are specially bred as food for crayfish and fish.

In feeding ponds, the crayfish feeds only on part of the zooplankton - the larvae of the pusher mosquito and other mosquitoes. Mosquito larvae, chironomids or tendipedids, known as bloodworms, are of primary importance for feeding crayfish. Mollusks and their various forms contained in benthos are of some importance in the nutrition of crayfish.

Harmful insects to crayfish in a pond include water beetles, bedbugs and dragonflies. The beetles even attack crayfish fry. Particular harm to juvenile crayfish is caused by such beetles as reindeer, pond snail, water lover, diving beetle, silt beetle and their larvae. Adult dragonflies and their larvae consume crayfish food. Frogs and tadpoles also consume crayfish food. Tadpoles also eat cake, the food given to crayfish.

How to breed crayfish in ponds

Crayfish are bred in ponds of complex importance; drained bays of reservoirs specially built for crayfish breeding; massifs of peat workings; quarries; small reservoirs; sections of small rivers; estuaries; ilmenyah; lakes; rice fields, etc.

Based on the nature of water supply, ponds are divided into key, stream, river, channel, floodplain, etc.

Key ponds are supplied with water from permanent springs. They are usually constructed by embanking part of the valley or beams adjacent to the terrace above the floodplain, from which springs flow. Most ponds have a uniform depth throughout the area. At the dam they are made a little deeper - 1–1.5 m. As a rule, the water in the spring ponds is cold, with the exception of large ones with an insignificant flow of spring water. The size of ponds usually does not exceed 5 hectares, but larger ones are also found. Chemical composition pond water fluctuates greatly and mainly depends on the quantity and quality of water in the spring and on the soil on which the pond is located. In most cases, key ponds are flowing.

Stream ponds are replenished with water from streams that have a constant flow of water from springs. Ponds are created by blocking the valley with a transverse dam. These ponds have a deep part near the dam with a gradual decrease in depth towards the tops of the ponds. Such ponds usually have a well-developed coastal zone. The water temperature depends on the distance the water travels before it enters the pond, the size of the pond and the flow rate of the stream. At the sources the water is cold, further from the source and in the absence of coastal springs it is warmer than at the source, no colder than in ordinary lowland rivers. The area of ​​these ponds is small - from 5 to 10 hectares, but can be 25–30 hectares.

River ponds are supplied with water from rivers. According to the nature of their structure, they are divided into channel and floodplain. Channel dams are created by blocking the river valley with a transverse dam. The main purpose of the dam is to use water energy for small hydroelectric power stations, driving mills, grist mills, butter churns, to supply water to crab nurseries located in the floodplains of the river below the dam, etc. The area of ​​such ponds can be from 5 to 350 hectares. The depth of the reservoir is usually at least 3–4 m. Towards the top and along the banks, the depths go to zero.

Ponds are generally warm-water and durable. The salt composition of the water in them depends on its quality in the river, the drainage area and its drainage, on the nature of the bottom bed and on ground inflows. Floodplain ponds are formed when the lower part of the floodplain is embanked. Water is supplied to the ponds to the level of the pond's water horizon using a dam that raises water in the river and canal, which is located in the elevated part of the floodplain. Such ponds are located in the floodplain of the main river and are supplied with water from a channel.

Floodplain ponds are arranged for breeding crayfish, as well as for gravity irrigation of land plots located on the floodplain below the pond. Ponds vary in size; in crayfish farms they are made with an area of ​​30–100 hectares. At the dam, the depth of the ponds does not exceed 1.5–2.0 m and gradually decreases towards the terrace above the floodplain. The chemical composition of pond water is determined by the quality of the river water and the soil of the pond bed. Summer rainwater and ground currents have almost no effect on water quality.

Atmospheric ponds are powered by surface runoff. As a rule, they are filled with groundwater and rainwater (ground-atmospheric nutrition). Ponds are constructed by blocking wet hollows and gullies that have inflows of surface groundwater. At the dam the depth of the ponds is 1.5–2 m, then it gradually decreases towards the top. The area of ​​soil-atmospheric ponds can be from 10 to 50 hectares. The composition of water is determined by the quality of spring water flowing from the catchment area, the soil of the bed and groundwater. In winter, death is observed in such ponds.

Ponds with atmospheric water supply are built in the same way as soil-atmospheric ones, only they are laid in dry valleys and ravines that do not have an inflow of surface groundwater. They are supplied with water from spring and summer runoff. The area of ​​the ponds is 10–50 or more. Such ponds are inhabited by crushed crucian carp.

Floodplain dams are among the reservoirs with ground-atmospheric water supply. They are erected by embanking a section of the floodplain or by means of a transverse dam in the lower part of the floodplain, flooded by flood water. From the beginning of the decline in low water, shields are installed in the dams to block the water.

Dams are located in logs above the water horizon in the river. Every year they are filled with flood waters. They are replenished with water from summer runoff from the local catchment area and partly from groundwater. Dams are mainly used for breeding crayfish and for irrigation. The area of ​​such ponds is from 5 to 100 hectares. Their banks are flat and overgrown with vegetation. Steep and steep banks are rare.

When constructing new ponds and devices for breeding crayfish, the following should be provided: a drainage system that allows water to be drained and drained the pond bed for the winter or only in the fall for the time of catching crayfish, as well as a crayfish-barrier top that prevents crayfish from leaving the ponds if they are built on small rivers and streams.

If for some reason the water from the pond cannot be drained, two or three ponds should be built, placing them one after the other. With this arrangement of ponds, water is first drained to catch crayfish from the lower pond, then it is filled with water from the pond located above. The upper pond is left drained for the winter, and the remaining water reserves in the lower pond are used for various needs.

How to make drainage ditches. A proper pond ditch network includes a main ditch, side branches to low areas, and upland ditches that intercept groundwater and eliminate swamping of individual areas of the pond. It is necessary to arrange drainage ditches in such a way as to ensure complete drainage of water from low areas, as well as to drain the pond bed.

In terms of their design, ponds must comply with sanitary and hygienic requirements aimed at creating unfavorable conditions for the development of malaria mosquito larvae. To avoid swamping of areas adjacent to pond dams, quarries are made drainage or a ditch is provided for discharging seepage water and draining the adjacent area. The river bed located below the dam is straightened to lower the water level in the river and drain the floodplain. Small ponds and large ponds with shallow floodplains should be avoided.

When constructing complex ponds, special attention should be paid to their depth. For breeding crayfish in the northern regions and the middle zone, the average depth of ponds should be within 0.8 m, in the southern regions - 1 m. For feeding ponds, such ponds are optimal. At greater depths, crayfish production decreases. When constructing floodplain ponds in specialized farms, smaller average depths are allowed. In some cases, at such depths, the productivity of crayfish becomes greater.

The choice of sites for constructing ponds is of great importance for crayfish production. Ponds can be built on a variety of plots of land with different soils, provided that dams can be built on them and the areas filled with water. The more fertile the soil of the pond, the higher the productivity of crayfish in it.

Quite often, low-fertility soils that are unsuitable for arable land are allocated for ponds - saline, dry areas in ravines that produce low yields of grass, etc.

How to breed crayfish in the bays of reservoirs

Navigable and energy reservoirs differ from ordinary reservoirs by strong fluctuations in water levels, especially in summer period when the flow of water into the reservoir is reduced to a minimum. In various reservoirs, such fluctuations reach 2 -17 m. As a result of a decrease in the water level in the reservoir, a temporary drying zone is formed. This feature is sharply expressed in reservoirs of the plains with their vast areas of shallow water, constituting from 40 to 80% of the reservoir area.

Typically, shallow waters are drained in the autumn. winter period. During the spring flood, the drained areas are again covered with water. In seasonal reservoirs they are completely covered, in reservoirs of long-term regulation - completely in high-water years.

In contrast to the temporary drainage zone, the non-dischargeable part of reservoirs is called a permanent flood zone. For the life of crayfish in reservoirs, the zones have different meanings. The zone of constant flooding is the wintering site, and the drying zone is usually the breeding site. Both zones can be successfully used for breeding crayfish.

Draining large areas of shallow water and at the same time completely freeing them from wild crayfish during this period opens up great prospects for organizing pond crayfish farming. Water level fluctuations occur here in the same way as in conventional reservoirs. The decrease in the water horizon begins in the summer and continues until the spring flood.

The drained areas of reservoirs suitable for constructing ponds are the floodplains of small rivers, streams, gullies, hollows and other depressions along which water flows from the drainage area into the rivers. In autumn these areas are drained and frozen in winter. During the spring flood, dried and frozen areas are again covered with water.

With the least amount of money, bays that cut deeply into the mainland and have a narrow exit into the reservoir can be used. The hydrological regime of fenced-off bays differs from ponds in that the bays are filled with water not directly from the drainage area, but from the reservoir, with the beginning of the water rise.

The water temperature in the ponds at this time is significantly higher than in fenced off bays, since more water enters the bays. cold water from reservoirs covered with ice. Subsequently, the water temperature in the bays is almost the same as the temperature of the ponds.

Fenced-off bays are divided into two groups according to water supply conditions. One group includes bays with dependent water supply, the other - with independent ones. Bays with dependent water supply receive water from reservoirs and when the water horizon drops, the reservoir is not replenished with water. Bays with an independent water supply can receive water from the reservoir in the spring, and after the water horizon drops, the water in the reservoir is supplied with water due to the constant influx of water in streams and rivers flowing into the bay. The salt composition can be different, since, in addition to soils, wastewater also affects the quality of water in bays.

According to the conditions for releasing water, bays are also divided into two groups - early and late release from water. The early release bays can be drained in the fall before freeze-up, the late release bays - only as a result of the winter lowering of the water horizon during the freeze-up period.

Bays, deeply cut into the mainland and freed from water at the end of September, are usually used for feeding ponds. This makes it possible to fence off large areas from the reservoir with dams in the autumn. To reduce the cost of crayfish production and maintenance, individual bays are made at least 15 hectares in size. The greatest depth of the bays should be close to the depths of the crayfish ponds - 1.5–2 m.

To completely drain the bays it is necessary that greatest depths were in the lower part of the bays, and gradually decreased towards the middle and upper parts of the bay. If there are streams flowing into bays, the depths of the ponds during the period of depression in the channel part should not exceed the height of the reservoir level.

How to breed crayfish in peat excavations

Peat massifs are divided into high, transitional and lowland. In the northern regions, highland peat bogs predominate; to the south, lowland peat bogs are more common. Raised peat bogs are formed as a result of the deposition of dying sphagnum mosses, wild rosemary, cotton grass, pommel, cassandra and other plants that tolerate high acidity, under which decomposition occurs slowly.

In lowlands, hollows, floodplains of rivers and on lakes, lowland swamps are formed as a result of the deposition of dying remains of reeds, sedges, cattails, reeds and other plants growing in an alkaline, slightly alkaline or neutral environment. In such swamps, the process of decomposition of vegetation remains is not inhibited. increased acidity, but a lack of oxygen. The water of lowland swamps contains little dissolved oxygen. Atmospheric oxygen is prevented from reaching decaying vegetation due to the layer of water covering the swamps. Transitional swamps occupy a middle position between highland and lowland swamps.

Exist different ways peat extraction, after which excavations of varying quality remain. With the hydraulic method, quarries look like long and wide reservoirs. If the machine-molding method is used with baggers or excavators, narrow and long quarries with a depth of 3 m or more are obtained. With the milling method, when peat is produced thin layers, the milling fields remain relatively large area, with a flat bottom. Such fields are most suitable for constructing ponds. The natural productivity of ponds on them is almost twice as high as ponds built on quarries that are mined hydraulically.

In peat workings, the soil is generally acidic, with a pH of 4.1–4.4, which means that the natural productivity of crayfish ponds there is very low unless liming is carried out.

The soil of peat excavations contains many organic compounds tightly bound to colloids of humic substances, which quickly adsorb phosphorus compounds found in the form of insoluble compounds. To use these organic compounds, it is necessary to eliminate the acidity of the water and provide a sufficient amount of oxygen in the bottom layers for the development of microorganisms that mineralize organic matter and enrich the water with nitrogen and phosphorus.

Ponds on peat workings are almost no different from ordinary ponds on peaty or loamy soils, except for the pH of the water, which ranges from 6.6–6.8. If you add lime to the soil every year, the pH of the water will approach neutral. In ponds in peat workings, the food supply develops well, especially zooplankton, the intensive use of which ensures high productivity of crayfish.

How to breed crayfish in reservoirs

Based on the nature of water supply, reservoirs are divided into several groups: with water supply from precipitation, from permanent sources and with mixed water supply.

Irrigation reservoirs are constructed to retain atmospheric water. In spring they are filled with water to the design level. In June, water is taken from the reservoir for irrigation, as a result of which its horizon decreases and the area is reduced by almost 70% of the area flooded in spring.

In such reservoirs, the stocking density of crayfish is calculated at average density, which is half the sum of the area of ​​the reservoir when planting crayfish and its area in August, after water consumption, or according to the maximum mirror of the spring flood. When calculating based on the maximum surface of spring flooding with a decrease in the area of ​​the reservoir in summer, crayfish need additional feeding.

For some industries, for example, starch, sugar factories, some metallurgical and others, industrial reservoirs are installed. These reservoirs can be quite successfully used for growing crayfish, provided that the water is released and the crayfish are caught in winter or early spring and then refilled with water during high water. For breeding crayfish, such reservoirs are best used using pond crayfish farming methods by annually populating and catching everything that is grown, for example, reservoirs that can be lowered or fished longitudinally, as well as by methods of reproducing herds that do not have conditions for reproduction and do not go with the water into time of spring flood.

To catch crayfish, when constructing new reservoirs, provision should be made for bottom drains to completely drain the water. Large reservoirs, the water from which is never drained, must be adapted for seine fishing by smoothing out the unevenness of the bottom. To do this, remove bushes, trees and thickets of tough vegetation and uproot stumps. After removing stumps and stones, the holes are covered with earth; The steep banks of ravines and rivers are cut at an angle of 45 degrees. If reservoirs are populated with crayfish, provision should be made for the construction of dismountable crayfish-barrier dams during floods.

How to breed crayfish in shallow lakes

The country has a huge number of small lakes that are quite suitable for successfully breeding crayfish, but they are almost never used for these purposes.

Floodplain lakes of various sizes are part of the hydrological complex of rivers, in the floodplains of which they are located and are divided into several types: oxbow lakes, riverbed lakes, central floodplain (valley), near-terrace floodplain and dam lakes.

Typically, floodplain lakes are shallow, with an average depth of 1–1.5 m; in summer, the water in them warms up well. The content of dissolved oxygen in water fluctuates sharply throughout the day. During the day, the water is oversaturated with oxygen; at night, the amount of oxygen decreases due to the intensive consumption of oxygen by algae and the decomposition of organic matter at the bottom.

In winter, when the lakes are covered with ice and snow, the oxygen in the water is gradually depleted by the decomposition of algae, which die off in the fall. Oxygen deficiency is accompanied by complete death. Therefore, crayfish farming in floodplain lakes is carried out by spring planting and mandatory autumn catching of grown crayfish.

Floodplain lakes have an excellent food supply. Despite prolonged coverage by a significant layer of water during floods, zooplankton maintains a constant species composition. Particularly strong development of phytoplankton and zooplankton is observed after the decline of high waters. The benthos is distinguished by its diverse species composition and abundant development, especially of larvae and chironomids. In large quantities in the lakes there are larvae of various insects, oligochaete worms and various mollusks. The residual mass of the bottom natural food of crayfish reaches 100 g per 1 square meter. m. In terms of natural productivity of crayfish, floodplain lakes are often superior to ponds.

As crayfish grounds, floodplain lakes are divided into several groups - drainage, non-discharge oblong oxbow lakes and wide lakes of the central floodplain. The bottom of the drainage lakes is located above the water horizon in the river, so they are easy to make drainage. Such lakes are no different from drainage ponds; the productivity of crayfish in them can be very high.

Non-draining oxbow lakes are oblong, small area, they can be well processed with longitudinal nets. Among the oxbow lakes there are also very large ones, from which crayfish are caught by pumping out water with powerful pumps. Non-draining lakes of the central floodplain usually have a large area and width and cannot be fished with longitudinal shallows either before settlement or in the fall. Crayfish can only be caught from them by pumping out water annually. The costs of pumping water do not exceed the costs of catching crayfish with seines. Leaving the bottom of lakes without water during the winter helps to increase their crayfish productivity.

Floodplain lakes, which are filled only in years of maximum floods, often become shallow and are not used for crayfish breeding. To drain such lakes, they dig a ditch or deepen the source enough to drain the remaining water and leave it for summer in years of minimal floods. Some lakes are shallow due to the great depth of the channels through which water flows during floods. The water level in them is increased in various ways. For example, a simple sluice is built on a discharge ditch. The lock consists of sheet piling rows at the level of the lowest water horizon and piles, which have a lateral connection with the banks by enclosing the sides with slabs, planks or blocks. The space between the side walls of the gateway is filled with soil or peat and compacted. The gateway is covered with shields inserted into the grooves of the piles in two rows. The lock is opened for the winter. When the level of spring water rises, it freely passes through the sluice and fills the reservoir.

To prevent wild animals from entering the reservoir, gratings with vertical rods are inserted into the grooves. When the water level begins to drop, the grates are removed and the sluice is closed with two rows of panels. To reduce water loss, soil or peat is poured between the panels, leaving them until autumn. During the autumn descent, shallow waters overgrown with hard vegetation are cleared of water, which improves conditions for catching crayfish.

How to breed crayfish in ilmen and estuaries

Ilmeni (depressions) are located in the southwestern part of the Caspian basin, between sandy and silty ridges. Ilmeni have an elongated shape, their bottom is muddy, the banks are sandy and flat, the depth is 1–2 m, the area is from 30 to 100 hectares. Almost all ilmens are connected by channels through which flood water flows. total area The Ilmen fund is about 173 thousand hectares. Ilmen, which in ancient times had some importance for the reproduction of cancer stocks, has now lost its former importance.

In the area where the ilmens are located, adjacent to the western part of the Volga delta, summer is usually hot, long, with an abundance of sunny days. There is little precipitation. The amount of oxygen dissolved in water in summer ranges from 6.2 to 16 ml per 1 liter. In deep-sea ilmen, the oxygen content in winter ranges from 50 to 92% saturation. The growing season lasts almost eight months; the bottom of reservoirs is rich in food for crayfish.

In the Volga delta, winter lasts only three months with short frosts. In such conditions, for breeding crayfish, it is possible to completely dispense with the construction of wintering ponds, which are the most expensive part of a crayfish nursery.

According to specialists’ calculations, when pumping out the remaining water in the fall to catch crayfish, it is possible to create a pond farm on an area of ​​60 thousand hectares with an annual capacity of up to 300 thousand crayfish. Ilmeni, which are not subject to winter death, are also suitable for growing crayfish. It is recommended to populate them with yearlings and catch marketable crayfish not in the same year in the fall, but a year later, when the three-year-old carp reaches a weight of 2 kg. When growing for three years, you can pump out water and catch crayfish not from all the ilmen, but from half of them, which will reduce labor costs by half and ensure the production of large, highly valuable crayfish.

With a three-year cultivation period, the need for cancer-planting material is half as much as with a two-year period. With proper crayfish operation of ilmens, draining them using pumping units you can get more than 3 quintals, and in 2 years - 6 quintals from 1 ha. This is exactly the productivity of crayfish in the Volga delta that was obtained in the ilmen with an area of ​​75 hectares in the Astrakhan region.

As a rule, ilmens are distinguished by a rich food supply. The benthos biomass here on average per year is 477 kg per 1 ha, compared to 103 kg in the ilmen of the central delta. The biomass of plankton is correspondingly 8 g instead of 5.2–6.5 per 1 cubic m of water. In summer, the biomass of ilmen is on average about three thousand organisms weighing 48 g per 1 square meter. m.

The drainage ilmens available in the Volga delta can be used for the joint cultivation of fingerlings and table crayfish with the release of fingerlings into the river for the reproduction of crayfish stocks. When two-year-olds and underyearlings are raised together, the cancer productivity of ilmen can be increased by 45–55%.

Estuaries located at the mouths of rivers flowing into the Azov and Black Sea, arose in connection with the formation of deltas as a result of centuries-old river sediments and the action of sea waves, forming spits and bays. Numerous Kuban estuaries arose on the site of a sea bay, separated from the sea by a spit, which was gradually filled with sediment from the Kuban River.

The area of ​​the estuaries is constantly changing. The reasons for the changes are flat banks, shallow depths, fluctuations in the water horizon depending on its influx, etc. The shallowness of the estuaries determines their unique thermal regime, characterized by rapid heating of water in the spring and rapid cooling in the fall. In spring, the water temperature in the estuary is warmer than in the sea, and in autumn it is colder. Quietly hot weather The water temperature reaches more than 35 degrees Celsius. In the thickets during the day, the water temperature at the bottom is 7–9 degrees lower than at the surface.

In winter, for an average of 75–80 days, the estuaries are covered with ice 15–30 cm thick. In severe winters with prolonged ice cover and large ice thickness, death occurs.

Many estuaries are silted, the silt layer usually reaches 0.5 m, in some 2–3 m. The salinity of the water is variable and depends on the connection with the river and the sea. Most of the Kuban estuaries are desalinated, their salinity is no more than 2%, while the salinity of the Azov Sea reaches almost 12%.

Most estuaries are heavily overgrown with coastal reeds, cattails, sedges, etc. The common underwater vegetation is chara, hornwort, pondweed, and urut. The spring cycle of zooplankton development begins in April. The biomass of zooplankton reaches 18 g per 1 cubic meter. m of water. In estuaries where salinity reaches less than 5%, crustaceans, chironomid larvae, and various mollusks develop well. Zooplankton and zoobenthos are richer in saline estuaries.

Currently, according to the scheme of crayfish reclamation measures for the reproduction of commercial crayfish in water bodies Krasnodar region The main area of ​​the estuaries is allocated for the construction of nurseries. 16 thousand hectares of estuaries and all dead-end estuaries that are not important for the reproduction of commercial crayfish in the Sea of ​​Azov are allocated for the construction of commercial farms.

How to breed crayfish in small rivers

A good base for growing crayfish are sections of small rivers, the length of which is more than 1 km. Small rivers are divided into mountain and lowland. The flow of rivers makes it possible to feed crayfish in them during compacted plantings and thereby increase the productivity of crayfish to 18 c per 1 ha.

The area of ​​rivers can be significantly increased by installing simple bridges on them, allowing them to raise the water horizon and at the same time use them as headwaters to retain crayfish in a fenced off section of the river. Before planting the crayfish, areas fenced off with jumpers must be carefully fished with nonsense.

How to transport crayfish

It is best to transport crayfish in baskets filled with dry, smooth straw or dry moss. When receiving crayfish at their destination, you should not immediately transfer them to water; you must first water them from a watering can while they are still in the basket.

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