SU1699392A1 - Method for cultivation of crawfishes - Google Patents

Abstract

The invention relates to the artificial breeding of crayfish and can be used on cancer hosts. The purpose of the invention is to increase the survival rate of females after spawning and larvae and reduce the time required to obtain marketable products. The essence of the invention is that, after 2.5-3 months of crayfish, the crayfish are additionally kept in containers with controlled environmental parameters until they reach commercial sizes, the rate of water exchange during the period of larvae is maintained at 6 - 10 l / min after the jigging of females at the level of no more than 12 l / min, during the period of additional keeping of juveniles in tanks with controlled environmental parameters - at the level of 13-18 l / min, while the density of planting of juveniles leaves 75-150 pcs. / m2 The females are fed to the larvae before the transition. for feeding, and as the substrate for the larvae, del is initially used, and after differentiation of the floors - sand 2 tab. V,

Description

The invention relates to the cultivation of crustaceans and can be used in the breeding of crayfish in artificial conditions.

With the modern cultivation of crustaceans, industrial methods are becoming more widespread, based on the content of hydrobionts during compacted landings using artificial feed and maximum flow.

The known method of cultivation of crayfish includes obtaining larvae in incubation tanks, growing their nursery ponds at the age of the youngsters, wintering the younglings and growing two-year-olds to commercial size (length 10-11 cm, weight 30-40 g).

The disadvantage of this method is the inability to regulate the growth of cancers and accelerate it.

The closest in technical essence and the achieved result to the proposed method is the Simplified method for obtaining planting material of crayfish, including the production of larvae in incubation tanks with water flow 80-100 l / min / ha, the content of larvae for 25 days in baths with water flow of 20 l / min at a temperature C with a planting density of 3-6 thousand pieces / m2 on the substrate in the form of lattice ppastin,

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her wasps

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feeding them in 2–3 doses and the next-i-following transfer of juvenile fish into ponds for rearing to commercial size.

The disadvantages of the described method are the following:

1) the lack of feeding of females and larvae that were not separated from them during the incubation period, which leads to a decrease in the release of larvae and mortality of females after spawning;

2) flow through water in incubation tanks of the order of 80-100 l / min / ha and 20 l / min with subsequent maintenance of the larvae, the substrate in the form of lattice plates does not meet the biological needs of females and larvae during this period, as a result survival (larval survival is 80%);

3) in this method, commercial cancer is obtained at least 2 years after the larvae are obtained, the technological process presupposes the presence of a system of nursery, wintering and feeding ponds.

The purpose of the invention is to increase the survival rate of females after spawning and larvae and reduce the time required to obtain marketable products.

This goal is achieved by the fact that the young of the crayfish after 2.5-3 months of keeping in the ponds are additionally kept in containers with controlled environmental parameters until it reaches commercial size, the rate of water exchange during the period of larvae is maintained at 6-10 l / min after felling of females at the level of not more than 12 l / min, during the period of additional keeping of young fry in tanks with controlled environmental parameters at the level of 13-18 l / min, while the density of landing of young fry is 75-150 p / m2 The females are fed during the preparation of the larvae before the larvae migrate to active power, as a substrate for the larvae initially used Del, and after differentiation floors - sand,

The present invention has the following advantages over the known:

1) maintaining flowage in incubation tanks at a level of 6-10 l / min imitates the natural conditions of spawning and creates a favorable mode for hatching of larvae;

2) feeding the females and larvae before their transition to active feeding allows -0

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does not increase the viability of females and larvae (survival rates of 98-100% and 95-100%, respectively);

3) use as a substrate for the maintenance of larvae before differentiation of the sexes, and then sand 7–10 cm deep also increases survival, since it imitates natural shelters;

4) flowability of 13–18 l / min and a density of 75–150 pieces / m2 in tanks at the last stage of cultivation provides the optimal hydrochemical regime for the cultivation of commercial cancer;

5) translation of crayfish after 2.5–3 months of keeping in nursery ponds in a tank with controlled medium eliminates their wintering and subsequent keeping in feeding ponds and speeds up the production of crawfish size 2.5–3 times

The method is carried out as follows.

Female crayfish with caviar are delivered to the incubation workshop and transplanted into adaptation pools. After adaptation, females with caviar are transplanted into devices for breeding crayfish, for example, according to Aut. No. 1364256, which, in connection with design features, feed them during the entire incubation period.

To ensure a sufficient number of larvae, they are obtained in batches at least twice — the first batch immediately after mating of the producers, and the second batch in periods close to their natural spawning. Larvae are obtained by known methods, for example, by auth. No. 1329716.

Females with caviar are kept until the larvae are obtained in water with a flow rate of 6–10 l / min and are fed during the entire incubation period with balanced feed AD-1 (wheat bran - 28%, wheat - 14%, barley - 10%, sunflower meal - 20%, soybean meal - 5%, fishmeal 12%, hydrolysis yeast - 7%, herbs for flour - 1%, vegetable oil - 2%, premix - 1%). The size of the diet of females to reach the eye stage is 0.7% wet weight, then decreases to 0.35% after the larvae hatch — 0.2% (females 3 days after hatching the larvae do not feed, and to the larvae that separate from females only 7-10 days through the water fed nutrients

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the company). The frequency of feeding is one time per day in the morning or evening.

After the second molt, the larvae of the females are removed from the devices together with the upper platform, and the resulting larvae 1-1.1 cm long and weighing 30-37 mg are left to grow in the same containers with a density of 5 thousand pieces / m2 during water exchange 10 -12 l / min. The water temperature is maintained at 22-24 ° C.

The larvae are fed to them with feed AD-1 at the rate of 10-13% of wet weight. After swarming, switch to AS-1 feed (hydrolysis yeast - 10%, dry milk - 20%, fish meal - 35%, soybean meal - 15%, sunflower meal 15%, vegetable oil - 4%, premix PM-2 - 1%) at the rate of 8-10% of wet weight.

The first batch of larvae is kept on the substrate, and then the del is removed and sand is 7-10 cm deep. This batch of larvae is grown for a month until the larvae reach a length of 2.5-3.0 cm and a weight of 350- 400 mg.

The second batch of larvae was grown for 2 weeks on a delhi substrate until they reached a length of 1.3-1.4 cm and a weight of 70-100 mg.

Then the young of both batches are transported to nursery ponds and transplanted with a density of 30 pcs / m2. The content in the ponds continues during summer time (June-August) - 2.5–3 months. The young during this period reach a length of 7–8 cm and a mass of 13–18 g.

larvae plantations were 5000 mg / m2. After two weeks, in connection with

At the last stage of breeding, the young of the crayfish were transferred from ponds to tanks with controlled medium with a density of 75-150 pcs / m2 and flow through them were grown for another two weeks with a water density of 13-18 l / min, temperature

due to the fact that the water temperature in the ponds (16 C) did not allow the release of juveniles,

2000 mg / m2, and a 7–10 cm layer of sand was used as a substrate. The young reached a length of 3.07 + 0.3 cm and a mass of 393–0.05 mg. Survival rate was 90%. I

water 22-24 C, oxygen concentration 6-8 mg / l. After 2.5-3 months, the crayfish reach the field size - length 10-11 cm and weight 30-40 g.

The density of planting of cancers in each case is determined by taking into account the data on their breathing, the volume of water, the amount of oxygen dissolved in it and the critical (minimum) oxygen content (3 mg / l), which cannot be consumed for breathing and should serve as a reserve for boiling. crayfish. The data are given in table. one"

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Example 1 “Calfs were harvested at the end of April immediately after mating, and brought to adaptation pools with a water temperature of 18–22 ° C, kept for 24 hours, and placed in crayfish breeding machines on the basis of auth. К ° 1364256 During the whole spawning period, females were fed AB-1 fodder mixture. The size of their ration until the caviar stage reached the ocellus was 0.7% of their wet weight, then 0.35%, and after the larvae hatch and before they were separated from the females, 0.2%. As a result, the nutrient supply of the females does not decrease, the females easily change after the larvae are obtained.

The water flow rate during the maintenance of females was 5 l / min, the oxygen concentration was 6 mg / l, and the water temperature was 22 ° C. On caviar, 12.6% of females developed saprolegnis.

After the second molt, the larvae of the females were deposited from the device, and the larvae were left in the same containers for growing.

The survival rate of females during the spawning period was 95%, during the period of molting and before hardening of the shell - 97%. The average yield of larvae compared with physiological fertility was 64.7% „

The length of the larvae during the transition to independent feeding was 1.1 + + 0.394 cm, weight - 37.04 + 0.9 mg. The larvae were grown at a water temperature of 22 ° C, water exchange at 12 l / min. As a substrate, a del of various configuration was used. Density

larvae plantations were 5000 mg / m2. After two weeks, in connection with

they were grown another two weeks; the flesh was grown another two weeks with the raps, in that the water temperature in the ponds (16 C) did not allow the young to release,

they were trained for another two weeks with a raft

2000 mg / m2, and a 7–10 cm layer of sand was used as a substrate. The young reached a length of 3.07 + 0.3 cm and a mass of 393–0.05 mg. Survival rate was 90%. I

Then grown young crayfish from

the tanks were transplanted into adult ponds, where they were grown for 2.5 months at a planting density of 30 mg / m2. Zooplankton biomass — at the time of transplantation, the young in the ponds were at least 3 g / m3. Survival in ponds 85%.

After the specified period, the cancers were transplanted again in containers with controlled parameters of the medium, in particular, the water strength was 12 l / min, temperature 22 ° С, oxygen content 8 mg / l, and were grown for 3 months. Plastic and ceramic nests were used as substrates. The cancers were fed AS-1 as food, the ration value, as they grew and accumulated mass, varied from 2% of wet weight to 0.7%.

By the end of the cultivation, the crayfish reached a commercial size, the length was 10.0 + 0.547 cm, the weight was 35.8 + 0.395 g.

The survival rate at the stage of additional cultivation in containers with controlled medium is 90%.

Overall survival from the resulting larvae was 42.6% 0

Example 2. Analogously to example 1, females with caviar were kept in water with a flow rate of 6.5 l / min, the larvae after jigging females for a month were ground in water with a water exchange rate of 13 l / min, at that time a change in behavior was noted and anxiety.

The survival rate of the larvae after rearing during the month was 90% t after rearing in ponds — 84%.

The rate of water exchange in tanks with controlled environmental parameters remained at 13 l / min. The survival rate at this stage is 91%. Overall survival rate from the obtained larvae was 54.5%.

Example 3. Analogously to example 1, the rate of water exchange was - when keeping females with caviar and receiving larvae - 8 l / min, after jigging females - 12 l / min (larvae survival rate 96.5%), after transplanting from ponds in additional content - 15 l / min. Survival at the last stage of cultivation - 95% "Total survival rate from the obtained larvae - 69.0%"

Example 40 Analogously to Example 1, the rate of water exchange in the period of larval production was 10 l / min, after the deposition of females - 12 l / min (larvae survival rate 95.0%), during the period of additional content in. containers with controlled environmental parameters - 18 l / min (survival rate of 90.8%) „Total survival rate of larvae from the resulting was 65.3%, crayfish reached fishery

the left size is 10.2 + 0.159 cm in length and the mass is 37.9 + 0.18 g.

Example 5. Similarly to the example

The rate of water exchange in the period of larvae production was 12 l / min, after the jigging of females it remained at the level of 12 l / min (larvae survival rate of 89.2%). in the period of additional content

in containers after the pond - 20 l / min. The young reached a commercial size, the survival rate at the last stage was 78%. Overall survival from the resulting larvae was 47.7%.

However, during the preparation of the larvae and the additional content after transplantation from the pond, due to the high rate of water exchange, a considerable part of the feed was removed, and the water and energy consumption for its heating increased, which could not be considered appropriate.

The results of experiments 1-5 are summarized in table. 2

 Example 6. Similarly to the example of 3 females with caviar and larvae that did not secrete from females did not feed. As a result, after the separation of the larvae from the females, the survival rate of the latter was 80%, and the larvae had a reduced viability, their survival after 2 weeks of growing was 32% , the survival rate in the ponds of the remaining larvae is 75%.

At the end of the cultivation, the survival rate was 90%. Overall survival rate - 35.2%.

Example 1 “Similarly, RU 3 juvenile crayfish were grown in ponds for 3 months. The length of the crayfish during this period reached 10.32 + 0.48 cm, weight 38.946+ +1.058 g0 Survival rate 83.8%.

Example 8. Analogously to example 3, young crayfish were kept in ponds

2 months. The length of the crayfish — when released from ponds — was 8.27 + 0.32 cm, weight 29.500 + 0.320 g. With further cultivation, you dreamed that in order to achieve marketable weight it was necessary to have a longer content in containers with controlled environmental parameters, which was economically disadvantageous

Example 9

3 young crayfish kept in ponds

4 months (from June to September) However, their growth ceased at the end of August as a result of a decrease in temperature to

15 С „Length of crayfish after 4 months

the content in the pond was 10.81 + 0.32 cm, weight 37.811 + 1.14 g, which corresponds to the size after 3 months.

Claims (1)

1. The method of cultivation of crayfish, including keeping the females with caviar, feeding them until larvae are obtained, separating the latter from the females and keeping them in containers with an artificial substrate at a water temperature of 22 to 24 ° C, oxygen concentration from 6 to 8 mg / l and a controlled rate of water exchange and the subsequent cultivation of fry to obtain marketable products containing them in ponds, characterized in that, in order to increase the survival rate of females and larvae, shorten the time for obtaining marketable products, fry contain crayfish dah for from 2.5 to 3 months, and further development to marketable products is carried out in containers at water exchange rates from 13 to 18 l / min, while the rate of water exchange while keeping females with caviar is set to 6 5 to 10 l / min, and when the content of the larvae in containers is no more than 12 l / min „ 20. The method of claim 1, wherein the substrate for the larvae is initially used del, and after the differentiation of sexes - sand. Table 1 Density of landing of females and young crayfish Mass in mg. Growing crayfish to commercial weight at different rates of water exchange (results of experiments 1-5) table 2