Method for recovering and thickening of procambarus clarkia diapause fry

Abstract

The present application belongs to the technical field of aquaculture, and relates to a method for recovering and growing of Procambarus clarkia diapause fry, which comprises two stages of diapause recovery and growing: first, the diapause fry is placed in recovery liquid A, and slowly warmed to room temperature at a rate of 2 DEG C per day to realize recovery of the vitality of the fry; then, the recovered fry is transferred to a growing system, and through management measures such as regulation of water quality (pH 7.5-8.6, salinity 0.10-0.50 ‰, water temperature 15-30 DEG C), hierarchical feeding (special feed in the early stage, and shrimp feed in the later stage), regular water change and probiotic supplement, the fry is cultivated to a size of greater than or equal to 1 g. The present application significantly improves the recovery rate (greater than or equal to 95%) and the survival rate (greater than or equal to 88%) of the diapause fry, shortens the cultivation period, promotes the cultivation of large-scale and high-uniformity fry, and provides stable fry source for the out-of-season cultivation of Procambarus clarkia.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, specifically to a method for the recovery and rearing of diapause seedlings of Procambarus clarkii. Background Technology

[0002] The red swamp crayfish (Procambarus clarkii), also known as the crayfish, is a very important freshwater economic shrimp species in my country. It is characterized by its strong adaptability and high farming efficiency, and its aquaculture industry has become one of the important pillar industries for rural revitalization and increasing farmers' income.

[0003] Traditional red swamp crayfish (Procambarus clarkii) farming relies heavily on natural reproduction to obtain spring seedlings. However, the concentrated supply of seedlings, uneven size, and unstable survival rates severely restrict yield increases and easily lead to concentrated market supply, thus impacting the healthy development of the entire industry. To address this issue, our team proposed a method for maintaining and storing red swamp crayfish in diapause. This method involves inducing diapause in the seedlings, halting their growth, and then resuming farming during the off-season to achieve a stable year-round supply. However, in existing diapause maintenance processes, the seedlings are affected by external environmental factors, resulting in stunted growth and decreased vitality. Direct release into ponds leads to extremely low survival rates. Therefore, combining effective diapause recovery techniques with efficient seedling rearing techniques is crucial for achieving a stable year-round supply of seedlings and ultimately ensuring a year-round crayfish population.

[0004] Although crayfish farming technology is becoming increasingly mature, a standardized and scalable technical procedure is still lacking in the recovery and high-survival-rate nursery stages of diapause larvae. Therefore, researching and promoting an efficient method for the recovery and nursery of diapause larvae of the red swamp crayfish will effectively bridge the gap between factory-style seedling production and outdoor pond farming, shorten the farming cycle, and ensure a year-round supply of live crayfish. This is of great significance for improving farming success rates, tapping into the production potential of ponds, maximizing industry benefits, and ultimately helping farmers increase their income and achieve prosperity. Summary of the Invention

[0005] Based on the biological characteristics of the red swamp crayfish, this invention solves the technical problems encountered in the large-scale recovery and rearing of red swamp crayfish larvae through industrialized rearing technology. It aims to provide a new technology for the rearing of red swamp crayfish larvae and innovates in process flow and technical methods to achieve large-scale, high-survival-rate seedling cultivation, providing a stable and high-quality seedling source for off-season aquaculture.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for the recovery and rearing of diapause-inducing Procambarus clarkii seedlings includes two core stages: diapause-inducing seedling recovery and rearing. Diapause recovery treatment: Place the diapause-bound Procambarus clarkii larvae into recovery solution A, which is prepared by adding 500-1000 mg of ascorbic acid powder per 1 L of water. Initially, lower the temperature of recovery solution A to the diapause temperature of the larvae (10°C), then place the diapause-bound larvae into it, and slowly increase the temperature at a rate of 2°C per day until the water temperature matches the room temperature (20-25°C). Successful recovery is determined when the larvae regain vitality, become active, and disperse.

[0007] Nursery rearing: Successfully revived shrimp larvae are transferred to the nursery system and further reared until they reach an individual size of 1g or more. The nursery system includes a main nursery pond and nursery net cages within it, equipped with water circulation, aeration, and biological filtration facilities. The nursery process includes precise water quality control, graded feeding, regular water changes, probiotic supplementation, growth monitoring, and disease control to ensure the healthy growth of shrimp larvae in a controlled environment. Furthermore, the construction and management of the nursery system includes the following key technical features: 1. Graining System Structure: The main coarsening tank has an area of ​​200-1000 m² and a depth of 0.7 m. It contains net cages with a projection area of ​​1-4 m² and a height of 0.6 m, with the bottom of the net cages suspended 0.1 m above the tank bottom. Each main tank is equipped with two water circulation pumps and one aerator, and oxygen is supplied to each net cage via a pipeline system. Each square meter of net cage is equipped with one biochemical cotton filter aerator and 30-60 vertically arranged brushes.

[0008] 2. Water Quality Control: The aquaculture water body needs to undergo aeration pretreatment for ≥7 days, maintaining a stable water temperature of 15-30℃, pH value of 7.5-8.6, salinity of 0.10-0.50‰, conductivity of 400-1500μS / cm, TDS of 200-1000mg / L, and water depth of 0.4-0.5m. Before stocking, a compound vitamin at a concentration of 200-500mg / L should be added to the water body to reduce stress on the shrimp larvae.

[0009] 3. Aquaculture Management: Stocking density is 500-1000 shrimp / m². Feeding strategy is divided into two stages: For the first 15 days, feed with self-made nursery feed (0.5mm particle size), 3-5 times daily, 10-15g / 10,000 shrimp per feeding; after 15 days, switch to commercial adult shrimp feed, at a rate of no less than 80g / 10,000 shrimp per feeding. From day 7 onwards, change 1 / 4 of the water every 7 days, and supplement each cubic meter of water with freeze-dried Bacillus subtilis powder and nitrifying bacteria powder (5g each per cubic meter). Monitor shrimp growth every 5 days and adjust the nursery period according to water temperature: 20-23 days when water temperature is 22-30℃; 28-32 days when water temperature is 15-22℃.

[0010] Homemade standard roughage with a particle size of 0.5mm is composed of the following ingredients by weight: soybeans: 17, corn flour: 10, fish meal: 18, algae: 10, shell powder: 11, squid paste: 12, flaxseed oil: 5, wheat flour: 5, allicin: 10, vitamin B: 1, vitamin C: 1.

[0011] The preparation method is as follows: Weigh the raw materials according to the requirements of each component of the feed formula → put the raw materials into a pulverizer and pass them through a 40-mesh sieve → put them into a mixer and mix them → add steam to the mixture and condition it to reach a conditioning temperature of 90℃, and continue to stir → use a pellet mill to make the mixture into pellets with a particle size of 0.5mm, keep them warm and moist for about 20 minutes → dry and cool.

[0012] The main components of commercial shrimp feed include: soybean meal, rapeseed meal, cottonseed meal, fish meal, wheat flour, corn flour, soybean oil, calcium dihydrogen phosphate, shell powder, molting agent, astaxanthin, compound vitamins, compound minerals, choline chloride, antioxidants, allicin, and yeast cell wall polysaccharides. The main components of the compound Bacillus freeze-dried concentrated powder are: Bacillus licheniformis, Enterococcus faecalis, Bacillus subtilis, lactic acid bacteria and other beneficial live microorganisms; The main components of nitrifying bacteria dry powder are: nitrifying bacteria, photosynthetic bacteria, Bacillus licheniformis, glucose, etc.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Improve the recovery rate of diapause seedlings: This invention effectively relieves the diapause state of red swamp crayfish seedlings by configuring a specific recovery solution A and combining it with a programmed slow-temperature activation process, which significantly improves the recovery rate and the consistency of vitality recovery of diapause seedlings, laying a solid foundation for subsequent nursery cultivation.

[0014] 2. Modular Nursery System Design: A modular nursery system design consisting of a main pond and net cages, equipped with high-efficiency aeration, biological filtration, and attachment substrate (brush), creates a stable aquatic micro-ecological environment. This not only increases the stocking density per unit area but also effectively reduces cannibalism among fry, significantly improving the survival rate of nursery stock.

[0015] 3. Refined water quality control: This invention effectively maintains the cleanliness and stability of the standard water body and reduces the risk of disease occurrence by optimizing the frequency and volume of water exchange, regularly supplementing probiotics (Bacillus, nitrifying bacteria) and stabilizing key water quality indicators (such as pH, salinity, conductivity, etc.).

[0016] 4. Precision Feeding Program: A phased precision feeding program was developed. Initially, easily digestible small-particle specialized feed was used, transitioning to nutritionally complete adult shrimp feed later, supplemented with nutritional fortifiers. This program not only meets the nutritional needs of shrimp larvae at different growth stages but also avoids stress and waste caused by overfeeding or uneven nutrition, promoting uniform and rapid growth of the shrimp larvae.

[0017] 5. Standardized Management Process: By establishing standardized operating procedures, the entire process from resuscitation to seedling rearing has achieved standardized and replicable management. This process effectively reduces production costs and management difficulty, providing reliable technical support for the off-season, large-scale, and efficient seedling production of Procambarus clarkii, and significantly improving economic and social benefits. Detailed Implementation

[0018] The technical solution of the present invention will be described in detail below through embodiments to verify the actual effect of the present invention, but the scope of protection of the present invention is not limited in any form by the embodiments.

[0019] The preliminary and material preparation for the following embodiments includes: (I) Design and construction of the progenitor pond for red swamp crayfish larvae (1) Construct multiple standard roughing main pools using concrete, each with an area of ​​400m². 2 The pool is 0.7m deep, and the length and width of the pool are adjusted according to the actual site. Each standard main pool is equipped with an inlet / outlet. (2) Set up 100 standard-coarse net cages (20 mesh) in each standard-coarse main pool, with a projection area of ​​2m² for each net cage. 2 The cage is 0.6m high, with the bottom suspended 0.1m above the ground. (3) Facilities: Each primary brooding tank is equipped with 2 water circulation pumps and 1 aerator (blower). Oxygen is delivered to the secondary brooding tank through the primary oxygen supply pipe. Each square meter of the tank is equipped with 2 biochemical cotton filter oxygenation heads. The other end of the secondary oxygen supply pipe is connected to the biochemical cotton filter oxygenation head. 100 special brooding brushes are placed vertically in each square meter of the tank. (ii) Diapause Procambarus clarkii larvae: The larvae were from the same batch that our team had previously preserved using diapause maintenance technology. They were uniform in size (0.01±0.002g) and had consistent vitality.

[0020] Resuscitation solution A: Take 1m³ of clean fresh water, add 500g of ascorbic acid powder, and stir thoroughly to dissolve.

[0021] Feed: 1. The initial 0.5mm standard roughage is composed of the following raw materials by weight: soybeans: 17, corn flour: 10, fish meal: 18, algae: 10, shell powder: 11, squid paste: 12, flaxseed oil: 5, wheat flour: 5, allicin: 10, vitamin B: 1, vitamin C: 1.

[0022] Preparation method: Weigh the raw materials according to the requirements of each component of the feed formula → put the raw materials into a pulverizer and pass them through a 40-mesh sieve → put them into a mixer and mix them → add steam to the mixture and condition it to reach a conditioning temperature of 90℃, and continue to stir → use a pellet mill to make the mixture into pellets with a particle size of 0.5mm, keep them warm and moist for about 20 minutes → dry and cool. 2. Commercial shrimp feed for later stages (Guangdong Haida brand crayfish special feed), the main ingredients are: soybean meal, rapeseed meal, cottonseed meal, fish meal, wheat flour, corn flour, soybean oil, calcium dihydrogen phosphate, shell powder, molting agent, astaxanthin, compound vitamins, compound minerals, choline chloride, antioxidants, allicin, yeast cell wall polysaccharide; 3. Compound Bacillus Concentrate Powder (Dileqi brand Yumuhui series product), main ingredients: Bacillus licheniformis, Enterococcus faecalis, Bacillus subtilis, lactic acid bacteria and other beneficial live microorganisms; 4. Nitrifying bacteria dry powder (Huachu brand), main ingredients: nitrifying bacteria, photosynthetic bacteria, Bacillus licheniformis, glucose, etc.

[0023] Example 1: The present invention provides a method for the recovery and brooding of diapause seedlings of Procambarus clarkii, comprising the following steps: Traditional pond direct grading operation (control group): Seedlings are raised directly in ordinary ponds without the construction of special greenhouses or complex facilities. Before stocking, the pond needs to be cleaned and harmful organisms killed. The water level should be controlled at a depth of 50-80cm, and Elodea and Alternanthera philoxeroides should be planted to cover 30-50% of the pond area to provide habitat and food for the shrimp larvae. At the same time, water quality should be cultivated. After that, brooding female shrimp are introduced. The larvae will naturally detach from the mother shrimp's abdomen and begin to grow. The main sources of nutrition are zooplankton, phytoplankton, organic detritus, and microorganisms in the pond.

[0024] This application discloses a method for the recovery and brooding of diapause-stage Procambarus clarkii seedlings: 1. Diapause Recovery: Resuscitation solution A was injected into the glass tank, and the water temperature was lowered to the dormancy temperature (10℃) for this batch of shrimp larvae using a chiller. Approximately 500,000 diapause shrimp larvae were gently placed into resuscitation solution A, maintaining oxygen supply. A heater was connected, and the temperature was slowly increased at a rate of 2℃ / day. After approximately 7 days, the water temperature reached the ambient temperature. Observations showed that the shrimp larvae began to become active from the 3rd day, and by the 4th day, more than 95% of the larvae exhibited rapid swimming and dispersion, indicating successful recovery.

[0025] 2. Cultivation of seedlings 2.1. Pond Preparation: After disinfection with bleaching powder, sludge removal, rinsing, and sun exposure, the main nursery pond is filled with tap water that has been aerated for 7 days, with a water level of 0.45m. The water quality is adjusted to: pH=8.0, salinity=0.2‰, conductivity=800-1000μS / cm, TDS=300-600mg / L, and water temperature=23℃. One hour before stocking, a 300mg / L concentration of compound vitamins is applied to the entire pond.

[0026] 2.2. Stocking: Soak the revived shrimp larvae bags in the pond water for 2 hours to allow for water temperature transition, and then evenly place them into 100 net cages at a stocking density of 800 larvae / m².

[0027] 2.3. Feeding Management: Days 1-15: Feed homemade roughage feed 3 times a day, 16g / 10,000 shrimp each time (i.e., total feeding amount per feeding is approximately 20g / 10,000 shrimp × 50 shrimp = 10,000g / feeding). From day 16 onwards: Switch to commercial adult shrimp feed, feed twice a day, 100g / 10,000 shrimp each time, and add a nutritional fortifier once a week.

[0028] 2.4. Water Quality Management: Starting from day 7, change the water every 7 days, with each change involving approximately 400 m³ (1 / 4 of the total water volume in the main pond). Remove uneaten feed and feces from the bottom using a siphon during water changes. After each water change, supplement with probiotics: 2000 g each of Bacillus freeze-dried powder and nitrifying bacteria. Growth Monitoring and Disease Control: Every 7 days, randomly select 100 shrimp larvae to measure their weight and body length; test the total Vibrio count and common pathogens in the water weekly.

[0029] Table of Results and Recommendations for this Example After 28 days of rearing (water temperature 22-26℃), the harvesting and measurement results are as follows: Table 1 Comparison of Key Indicators for the Growth and Nurturing of Red swamp crayfish Larvae

[0030] *Note: The traditional control group consisted of shrimp larvae from the same source that were raised in adjacent traditional earthen ponds during the same period, at a density of 800 shrimp / m².

[0031] The results of this embodiment demonstrate that the diapause recovery and nursery method provided by this invention achieves a high and stable recovery rate (>95%), providing a method for activating diapause seedlings; the nursery survival rate is significantly improved, indicating the effectiveness of the system design and management measures; precise environmental control and feeding strategies result in faster growth and more uniform size; the nursery survival rate, size uniformity, and yield per unit area comprehensively reflect the economic advantages of this technology. Through specific implementation methods combined with quantitative data comparison, the practicality and advancement of this invention are strongly demonstrated, providing empirical support for its promotion.

Claims

1. A method for the recovery and rearing of diapause-stage Procambarus clarkii seedlings, comprising two stages: recovery of diapause-stage seedlings and rearing, characterized in that, Diapause recovery treatment includes the following steps: Place the diapause-bound swamp crayfish larvae into recovery solution A. After lowering the temperature of recovery solution A to the diapause temperature of the larvae, place the diapause-bound larvae into the solution and slowly increase the temperature at a rate of 2°C per day until the water temperature matches the room temperature. Successfully recovered larvae are obtained when they regain vitality, become active, and disperse. Nursery rearing includes the following steps: Transfer the successfully recovered larvae to a nursery system and continue rearing until the individual size reaches 1g or more. The resuscitation solution A is obtained by adding 500-1000 mg of ascorbic acid powder to every 1 L of water; the standardization system structure is as follows: the main standardization tank has an area of ​​200-1000 m². 2 The pool is 0.7m deep, and the projection area inside the pool is 1-4m². 2 The net cages are 0.6m high, with the bottom of the net cages suspended 0.1m above the bottom of the main breeding pond. Each main breeding pond is equipped with 2 water circulation pumps and 1 aerator, and oxygen is supplied to each net cage through a pipeline system. Each square meter of net cage is equipped with 1 biochemical cotton filter aerator and 30-60 vertically arranged brushes. The breeding process also includes water quality control, gradient feeding, regular water changes, probiotic supplementation, growth monitoring, and disease control.

2. The recovery and coarsening method according to claim 1, characterized in that, The water quality environment is controlled as follows: the aquaculture water body needs to undergo aeration pretreatment for ≥7 days, the water temperature is maintained stably at 15-30℃, the pH value is 7.5-8.6, the salinity is 0.10-0.50‰, the electrical conductivity is 400-1500μS / cm, the TDS is 200-1000mg / L, and the water depth is 0.4-0.5m.

3. The resuscitation and coarsening method according to claim 1 or 2, characterized in that, Before releasing the shrimp larvae, a compound vitamin solution with a concentration of 200-500 mg / L should be sprayed into the water to reduce stress on the larvae.

4. The resuscitation and coarsening method according to claim 1 or 2, characterized in that, The breeding management is as follows: stocking density is 500-1000 fish / m². 2 .

5. The recovery and coarsening method according to claim 4, characterized in that, The feeding strategy is divided into two stages: For the first 15 days, feed the shrimp with self-made feed with a particle size of 0.5mm, 3-5 times a day, at a rate of 10-15g per 10,000 shrimp per feeding; after 15 days, switch to commercial adult shrimp feed, at a rate of no less than 80g per 10,000 shrimp per feeding; starting from the 7th day, change 1 / 4 of the water every 7 days, and add 5g of Bacillus powder and 5g of nitrifying bacteria powder to each cubic meter of water; monitor the growth of the shrimp larvae every 5 days, and adjust the nursery period according to the water temperature. When the water temperature is 22-30℃, the nursery period is 20-23 days; when the water temperature is 15-22℃, the nursery period is 29-32 days.

6. The recovery and coarsening method according to claim 5, characterized in that, Homemade standard roughage with a particle size of 0.5mm contains the following ingredients by weight: soybeans: 17 parts, corn flour: 10 parts, fish meal: 18 parts, algae: 10 parts, shell powder: 1 part, squid paste: 12 parts, flaxseed oil: 5 parts, wheat flour: 5 parts, allicin: 10 parts, vitamin B: 1 part, vitamin C: 1 part.

7. The resuscitation and coarsening method according to claim 5 or 6, characterized in that, The preparation method of homemade standard roughage with a particle size of 0.5mm is as follows: Weigh the raw materials according to the requirements of each component of the feed formula → put the raw materials into a crusher and pass them through a 40-mesh sieve → put them into a mixer and mix them → add steam to the mixture and condition it to reach a conditioning temperature of 90℃, and continue to stir → use a pellet mill to make the mixture into pellets with a particle size of 0.5mm, keep them warm and moist for about 20 minutes to stabilize them → dry and cool.

8. The resuscitation and coarsening method according to claim 5 or 6, characterized in that, The main components of the commercial shrimp feed include: soybean meal, rapeseed meal, cottonseed meal, fish meal, wheat flour, corn flour, soybean oil, calcium dihydrogen phosphate, shell powder, molting agent, astaxanthin, compound vitamins, compound minerals, choline chloride, antioxidants, allicin, and yeast cell wall polysaccharides; the main components of the compound Bacillus freeze-dried concentrated powder include: Bacillus licheniformis, Enterococcus faecalis, Bacillus subtilis, lactic acid bacteria, and other beneficial live microorganisms; the main components of the nitrifying bacteria dry powder include: nitrifying bacteria, photosynthetic bacteria, Bacillus licheniformis, and glucose.

Images