RU2525334C2 - Method of continuous breeding tropical crawfish - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: invention relates to the field of aquaculture. The method provides obtaining 2-3 generations of viable juveniles per year from females of tropical crawfish which are managed throughout a yearly cycle in the same container, common with males with the rate of stocking of no more than four family groups per 1 m². In the container the individual shelters are provided in an amount of at least one shelter for each crawfish and similar but smaller shelters for larvae and juveniles of crawfish in an amount of not less than 500 units per each square metre of the container. The light regime "day-night" of 14 and 10 hours, respectively, is created, for 2 months and 10 and 14 hours for 1 month with the fourfold repetition of this cycle throughout the year. The juveniles grown to 10-20 mg are caught at least once a week, while retaining formed family groups of crawfish.

EFFECT: invention provides obtaining planting material for organisation of year-round industrial production of marketable food crawfish.

4 cl, 1 tbl, 1 ex

Description

The invention relates to the field of aquaculture and is intended for year-round production of planting material for tropical cancer using for the organization of year-round industrial production of commercial food-grade cancer.

A known method for producing juvenile crayfish in the "biocomplex", based on the long-term maintenance in the pools of females with laid eggs, with a possible change in the timing of spawning due to preliminary thermal reactivation of females and males.

In this case, the hatching time of the larvae can be reduced or lengthened during 2-3 months of the spring-summer period [1]. The main significant disadvantage of this method is that spawning occurs only once a year for a relatively short period of time.

There is another method for producing juvenile crayfish, the essence of which is aimed at reducing the intensity of cannibalism and increasing the yield of planting material. The method consists in the fact that before hatching, the larvae of the female eggs are transferred to a separate container in which, after reaching the 2nd stage of development of the larvae, two oncoming water flows with a temperature different by 2-3 ° C are created, and the fodder for juveniles is set for fodder sites based on: 1 site for 10-15 individuals [2].

The main significant disadvantages of this method are:

- a single larval and juvenile obtaining from a single female during the year;

- the necessary transplantation of females with caviar in the last stages of development as a result of stress can lead to complete or partial abortive dropping of eggs;

- the presence of technical difficulties in creating oncoming water flows, placement and maintenance of a large number of feeding places, in the conditions of industrial application of the proposed method.

There is also known a method of commercial cultivation of tropical crayfish, one of the technological stages of which is to obtain larvae and juveniles in September-November from females that laid eggs during growing in a pond and kept in industrial conditions at a water temperature of 25-28 ° C without a long winter diapause [3].

The main significant disadvantages of this method, adopted by the applicant as a prototype, are:

- the possibility of only one-time obtaining of the larva in September-November for the subsequent rearing of juveniles and the growth of commercial cancer in the summer period;

- ineffective, single use of tropical cancer producers, capable, in their biological properties, of repeated spawning during the annual cycle.

- the need to transfer (transplant) females with laid eggs to industrial conditions from the pond, where they were raised during the summer under conditions close to natural conditions, which is accompanied by a sharp change in water composition, temperature and hydrochemical conditions and other external factors, which often leads to complete or partial abortive shedding of developing embryos, stress molting and death of a significant number of females.

The main task solved by the claimed invention is reliable year-round provision of multiple spawning of tropical cancer producers and year-round production of planting material.

The problem is solved in the invention due to the fact that 2-3 generations of viable juveniles are obtained from females of tropical crayfish, which are kept throughout the entire annual cycle in the same fish-breeding tank common with males, with a water temperature of 26-28 ° C , pH 7.5-8.5, with oxygen not lower than 7 mgO ₂ / L, with nitrogenous compounds within fish breeding standards for cyprinids and a density of no more than four family groups per 1 m ² , with individual shelters in the form of open cavities , in an amount of at least 1 shelter for each cancer, and a illogical shelters for larval and juvenile crayfish, but smaller cross-section, in an amount of not less than 500 units. for each square meter of capacity, they create a day-night light mode for 14 and 10 hours, respectively, for 2 months and 10 and 14 hours for 1 month with a four-fold repetition of this cycle throughout the year, with adults being regularly fed once cancers by eating, in the evening, each time with a separate type of natural food of animal or vegetable origin, and systematically, at least once a week, juveniles grown up to 10-20 mg are caught, and throughout the whole year formed family groups of cancers, not dividing them by sex and not transplanting for special pre-spawning preparation into separate containers with different conditions of detention.

In addition, the task is solved in the invention due to the fact that as an individual shelter it is proposed to use open cavities of round or square section with a cross-sectional area of at least 20 cm ² for adult crayfish and a cross section of 0.5-1.5 cm ² for larvae juvenile crayfish.

Neither from the materials of patent and scientific and technical information, nor from long-term practice in the field of aquaculture, was known about a method for breeding tropical crayfish with essential features identical to those claimed in a method for continuous breeding of tropical crayfish.

From this follows a legitimate conclusion about the novelty of the claimed technical solution. The claimed combination of essential features (significant differences) affects the receipt of a technical effect, while each of these features is necessary, and taken together are sufficient to obtain it, i.e. there is a causal relationship between the essential features of the proposed solution and the obtained technical result (expressed in the solution of the problem), where the set of essential features is the cause, and the technical result obtained is the result.

Here, the conclusion about the conformity of the claimed method to the criterion of "inventive step" is valid.

This solution, as shown by testing, can be implemented with its essential features repeatedly in a production environment, which confirms its compliance with the criteria of the invention - "industrial applicability".

The inventive method is tested in the semi-production conditions of the scientific-innovative production enterprise "Shrimp Consulting" and a small innovative enterprise "Eco-tropic". Below are the results of testing.

Example. Out of the number of adult commercial crayfish aged 6–8 months, grown in an open pond, in September, apparently undamaged, healthy, with pronounced secondary sexual characteristics of males and females were selected and family groups of 1 male and 3-4 were formed from them females. In total, 5 such groups were selected that, after a month of overexposure in a fish tank at a temperature of 26-28 ° C in October, were planted in a small fish tank (plastic pool) with an area of 1 m ² , a depth of 40 cm and equipped with a closed water supply system with forced aeration and adjustable temperature. An automatic water heater with a power of 300 W, adjusted to a maximum temperature of 28 ° C, was installed in the pool. A 100 W incandescent lamp and a time relay set for a 14-hour lamp on-time period (from 8 to 22 hours) were placed above the pool.

In the pool at the bottom, 20 shelters were placed for manufacturers in the form of scraps of polyethylene pipes with a diameter of 50 mm and a length of 150-200 mm. In addition, shelters for juveniles were installed at the bottom in the form of transverse strips of wall plastic panels 8-10 mm thick and 30-50 mm wide. The internal partitions of these panels create a cellular structure in which juvenile crayfish are freely housed. In total, such cells turned out 620 pcs.

During overexposure 3 females died. The total number of spawned producers was 23 ind. (5 males and 18 females, i.e. 5 family groups). When planting, it turned out that 2 females already hatched eggs.

Harvested feeds included: frozen - purified from fat and blood vessels beef spleen and liver, fillet of pike and perch, ground pumpkin and carrots, as well as buckwheat, millet, and hercules. Feeding was carried out in the evening, once a day, according to a pre-compiled calendar schedule, where only one type of feed was indicated for each day. The spleen, liver and fish were given in finely chopped form, ground vegetables and cereals - without preliminary preparation. The amount of food was not regulated - fed by eatability. Special feeds for juveniles were not introduced.

Maintenance of the spawning pool consisted of monitoring water temperature, aeration, weekly checking pH, oxygen concentration, nitrogenous substances (ammonium ions, nitrites). Every day, the pool was cleaned of solid waste using a siphon and replenishment of water losses during evaporation and cleaning (10 l per day).

During the first month of maintenance, intense competition for territory was observed among males and females. As a result, 1 male and 2 females died (1 of them with caviar). In November there were fewer conflicts, the males occupied a permanent territory and permanent shelters for themselves and actively guarded them, and females were located nearby in the shelters. In early November, the first crayfish larvae that left the female appeared, as well as two females with laid eggs. In the early days, larvae rarely appeared in open places - hiding under the tail of a female or in shelters. Later, their apparent number increased, and the first fishing with the help of a net gave 83 pcs. juvenile cancers weighing more than 10 mg each. The next harvest brought 46 pcs. They did not achieve a full catch of juveniles, because for this, it was necessary to raise all the shelters from the pool, which could have a negative effect on producers and, first of all, on females carrying eggs. Two months later, the day-night light regime was changed by 10 and 14 hours, respectively, and it was maintained for a month, after which the cycle was repeated every three months, which stimulated spawning activity and ensured physiological restoration of the producers.

In this mode, the spawning pool was operated for a full 11 months (until September of the following year, inclusive). In total, the appearance of females with newly laid eggs 43 times was recorded during this period.

The results of observations and registration of juveniles are presented on a monthly basis in table 1.

Table 1 month Number of females with newly laid eggs, pcs. Number of caught juveniles Number of victims, pcs. October 2 1 male, 1 female November 2 129 1 female December four 366 January 3 717 February 3 564 March four 525 1 female April 3 772 May 5 608 June four 983 July 5 819 1 female August 6 1077 September 3 1196 1 male Total 44 7756 2 males, 4 females

During the year of operation, one spawning pool with four family groups gave 7756 pcs. juvenile tropical cancer. The average productivity of one female was 189 pieces of juveniles at the age of no more than 2 weeks (3 females with caviar were not taken into account in September). Adjusted for death, the average number of females during the year amounted to 15 pcs., Hence, for each female an average of 2.9 spawning per year.

The proposed method for breeding tropical crayfish has several advantages compared to the prototype given in the application:

- provides continuous production of planting material of different ages throughout the year, regardless of the season;

- allows three times to reduce the number of producers required to obtain the same number of juveniles;

- reduces the stressful effects of technological operations on producers and young crayfish, thereby reducing the level of unproductive losses;

- simplifies maintenance of spawning pools and care for producers and juveniles;

- allows you to control and adjust the entire breeding process, starting with the selection of the composition of producers, spawning, and to obtain viable juveniles.

Information sources

1. N.Ya. Cherkashin. Dynamics of populations of cancers of the genera Pontastacus and Caspiastacus (Crustacea, Dekapoda, Astacidae) and ways to increase them. M., 2002

2. V.V. Yuknyavichus, E.K. Lekevichus. A method of growing juvenile crayfish. A.S. SU 1717034 A1.

3. A.I.Khoroshko. The method of commercial cultivation of tropical crayfish. A.S. RU 2340173 C2. - prototype.

Claims (4)

1. A method of continuous breeding of tropical crayfish on the basis of obtaining larvae from producers kept under industrial conditions, characterized in that they receive 2-3 generations of viable juveniles per year from females of tropical crayfish, which are kept throughout the entire annual cycle in the same common with males, fish tank with a water temperature of 26-28 ° C, pH 7.5-8.5, oxygen not lower than 7 mgO ₂ / L, with nitrogenous compounds within fish breeding standards for cyprinids and a landing density of not more than four family groups on 1 m ² , with individual shelters in the form of open cavities, in an amount of at least 1 shelter for each cancer and similar shelters for larvae and juvenile cancers, but of a smaller cross section, in an amount of at least 500 pcs. for each square meter of capacity, they create a day-night light mode for 14 and 10 hours, respectively, for 2 months and 10 and 14 hours for 1 month with a four-fold repetition of this cycle throughout the year, with adults being regularly fed once crayfish, by eating, in the evening, each time with a separate type of natural food of animal or vegetable origin, and systematically, at least once a week, juveniles grown up to 10-20 mg are caught, and throughout the year the formed family groups of crayfish are kept, not dividing them by sex and not transplanting for special pre-spawning preparation into separate fish breeding tanks with different conditions. 2. The method according to claim 1, characterized in that during the entire annual cycle in a fish tank with family groups of crayfish, the temperature and hydrochemical parameters of the water are optimal for spawning crayfish. 3. The method according to claim 1, characterized in that as an individual shelter use open cavities of round or square cross section with a cross-sectional area of at least 20 cm ² for adult crayfish and a cross section of 0.5 to 1.5 cm ² for larvae and juveniles crayfish. 4. The method according to claim 1, characterized in that only producers are fed once a day with only one type of natural feed or animal or vegetable origin.