A method for improving the survival rate of bighead carp in salt and alkali water breeding fry
By calculating the median lethal concentration (LD50) of bighead carp fry and conducting adaptive domestication, the problem of low survival rate of bighead carp in saline-alkali waters was solved, thus improving the survival rate and economic benefits of the fry.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEILONGJIANG RIVER FISHERY RES INST CHINESE ACADEMY OF FISHERIES SCI
- Filing Date
- 2024-11-08
- Publication Date
- 2026-07-24
AI Technical Summary
In the medium-to-high salinity waters of Northeast China, silver carp fry are prone to severe stress reactions when directly released from freshwater ponds into saline-alkali waters during the spring and autumn seasons, resulting in low survival rates and poor economic benefits.
By measuring the mortality rate of silver carp fry in water bodies with different alkalinity values, calculating the median lethal concentration, and conducting adaptive domestication in freshwater ponds, the fry were first placed in low-alkalinity ponds for domestication for 5-7 days, and then released into target saline-alkali lakes or marshes for aquaculture.
It significantly improved the survival rate of bighead carp in medium-to-high salinity water, enhanced the fish's resistance to adverse conditions, prevented fish mortality caused by excessive salinity, and improved economic benefits.
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Figure CN119302246B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fish farming technology, specifically to a method for improving the survival rate of silver carp fry raised in saline-alkali water. Background Technology
[0002] Bighead carp (Aristichthys nobilis), also known as silver carp, is one of the most important freshwater fish species for aquaculture in large and medium-sized lakes and reservoirs in my country. According to available data, the production of bighead carp reached 3,349,884 tons in 2023, ranking third in freshwater fish farming production, after grass carp and silver carp. Because bighead carp and silver carp primarily feed on plankton in natural waters such as lakes and reservoirs by filtering it through their gills, they are important fish species for purifying water quality and ensuring green ecological fisheries. Extensive production practice has shown that bighead carp has a greater advantage than silver carp in fish farming in large bodies of water such as saline-alkali lakes and marshes, exhibiting faster growth, higher survival rates, and better economic benefits, making it a major fish species for aquaculture in inland saline-alkali waters.
[0003] my country has abundant saline-alkali lakes and marshes, with the Northeast saline-alkali region being a typical carbonate-type water body. Due to the complex and diverse ionic composition and significant differences in salinity, fishery production has consistently remained at a low level. Numerous studies have shown that high alkalinity is a major key factor restricting the development of fisheries in saline-alkali waters. In the cultivation of silver carp in medium-to-high salinity waters, fish fry stocked in spring and autumn often suffer mortality due to excessively high alkalinity. Therefore, improving the survival rate of stocked fish fry in saline-alkali waters and expanding the area of suitable saline-alkali waters for aquaculture are crucial means to ensure the sustainable and stable development of fisheries in this region. The main reason for this is that fish fry stocked in saline-alkali lakes and marshes in spring and autumn are mostly cultivated in freshwater ponds. Directly releasing them into highly saline-alkali waters after harvesting causes severe stress in the fish. When this stress exceeds the fish's tolerance level, mortality frequently occurs, resulting in low survival rates and poor economic benefits from aquaculture. Summary of the Invention
[0004] The purpose of this invention is to address the problem of low survival rates and poor economic benefits of bighead carp culture in Northeast China. When fish fry raised in freshwater ponds are directly released into these medium-to-high salinity waters during spring and autumn, they experience severe stress reactions, often resulting in mortality when the stress exceeds the fish's tolerance. The invention provides a method to improve the survival rate of bighead carp fry cultured in saline-alkaline waters.
[0005] A method for improving the survival rate of silver carp fry cultured in saline-alkali water, comprising the following steps:
[0006] Step S1:
[0007] The bighead carp fry bred in spring are raised in freshwater ponds. In autumn or the following spring, when the bighead carp fry grow to 1 to 2 years old, the mortality rate of the bighead carp fry in water with different alkalinity values is measured within 12 to 96 hours. Then, based on the mortality rate, the median lethal concentration (LC50) of the bighead carp fry within 12 to 96 hours is calculated, and half of the L50 is taken as the maximum alkalinity value for bighead carp fry to be cultured in saline-alkali water.
[0008] Step S2:
[0009] Before releasing the bighead carp fry cultivated in freshwater ponds into the target saline-alkali lakes or saline-alkali marshes, the bighead carp fry are first released into low-alkaline pond water for acclimatization. The alkalinity of the low-alkaline pond water is 1 / 3 to 1 / 2 of the maximum alkalinity value of the saline-alkali water culture in step S1.
[0010] Step S3:
[0011] After the silver carp fry have been acclimatized in the low-alkaline pond water in step S2 for 5 to 7 days, they are then harvested and released into the target saline-alkali lake or saline-alkali marsh for further aquaculture.
[0012] The beneficial effects of this invention are:
[0013] (1) Based on the mortality rate of bighead carp fry in water bodies with different alkalinity values within 12-96 hours, this invention calculates the median lethal concentration (LC50) of bighead carp fry within 12-96 hours. Based on experimental results and production experience, the maximum alkalinity value at which bighead carp fry can be cultured in saline-alkali water is determined. Then, suitable target saline-alkali lakes, swamps, and other water bodies for bighead carp culture are screened and determined, avoiding the problem of low survival rates caused by blindly releasing fry into water with excessively high alkalinity, which leads to high stress and mortality in the fish.
[0014] (2) This invention utilizes target saline-alkali lakes, swamps and other water bodies to prepare low-alkaline pond water with a concentration of 1 / 3 to 1 / 2 of the maximum alkalinity for the aquaculture of bighead carp fry. Through the adaptive domestication of the fish, the fish's resistance to stress can be enhanced, and the stress response of fish fry raised in freshwater ponds directly placed into medium- to high-alkaline water bodies can be reduced.
[0015] (3) In this invention, after the fish fry cultivated in freshwater ponds are caught, they are released into low-alkaline ponds for 5 to 7 days of acclimatization and domestication, and then released into the target saline-alkali lakes, swamps and other water bodies for aquaculture. This can significantly improve the survival rate of fish fry in medium- to high-alkaline water bodies.
[0016] This invention provides a method for improving the survival rate of silver carp fry cultured in saline-alkali water. Attached Figure Description
[0017] Figure 1This indicates that fish species that have not undergone acclimatization were released into a highly alkaline water body with a concentration of 50 mmol / L, and intestinal tissue samples were taken after 24 hours.
[0018] Figure 2 This image shows the intestinal tissue of fish fry that have been acclimatized to 15 mmol / L low-alkaline water for 5 days and then released into 50 mmol / L high-alkaline water for 24 hours.
[0019] Figure 3 The diagram illustrates the process of calculating the median lethal concentration using SPSS 27.00.
[0020] Figure 4 This diagram illustrates the process of calculating the median lethal concentration using SPSS 27.00. Detailed Implementation
[0021] Specific Implementation Method 1: This implementation method is a method for improving the survival rate of silver carp fry cultured in saline-alkali water, and is carried out according to the following steps:
[0022] The bighead carp fry bred in spring are raised in freshwater ponds. In autumn or the following spring, when the bighead carp fry grow to 1 to 2 years old, the mortality rate of the bighead carp fry in water with different alkalinity values is measured within 12 to 96 hours. Then, based on the mortality rate, the median lethal concentration (LC50) of the bighead carp fry within 12 to 96 hours is calculated, and half of the L50 is taken as the maximum alkalinity value for bighead carp fry to be cultured in saline-alkali water.
[0023] Step S2:
[0024] Before releasing the bighead carp fry cultivated in freshwater ponds into the target saline-alkali lakes or saline-alkali marshes, the bighead carp fry are first released into low-alkaline pond water for acclimatization. The alkalinity of the low-alkaline pond water is 1 / 3 to 1 / 2 of the maximum alkalinity value of the saline-alkali water culture in step S1.
[0025] Step S3:
[0026] After the silver carp fry have been acclimatized in the low-alkaline pond water in step S2 for 5 to 7 days, they are then harvested and released into the target saline-alkali lake or saline-alkali marsh for further aquaculture.
[0027] The beneficial effects of this implementation method are:
[0028] (1) This implementation method calculates the median lethal concentration (LD50) of bighead carp fry within 12-96 hours in water bodies with different alkalinity values based on the mortality rate of bighead carp fry in water bodies with different alkalinity values within 12-96 hours. Based on experimental results and production experience, the maximum alkalinity value at which bighead carp fry can be cultured in saline-alkali water is determined. Then, suitable target saline-alkali lakes, swamps, and other water bodies for bighead carp culture are screened and determined, avoiding the problem of low survival rate of fry caused by blindly releasing fish into water with excessively high alkalinity, which leads to high stress and easy death of the fish.
[0029] (2) In this embodiment, the target saline-alkali lakes, swamps and other water bodies are used to prepare low-alkaline pond water with a concentration of 1 / 3 to 1 / 2 of the maximum alkalinity value for the breeding of bighead carp fry. Through the adaptive domestication of the fish, the fish’s resistance can be enhanced and the stress response of the fish fry raised in freshwater ponds can be reduced when they are directly put into medium- to high-alkaline water bodies.
[0030] (3) In this embodiment, after the fish fry cultivated in freshwater ponds are caught, they are released into low-alkaline ponds for 5 to 7 days of acclimatization and domestication, and then released into the target saline-alkali lakes, swamps and other water bodies for aquaculture. This can significantly improve the survival rate of fish fry in medium- to high-alkaline water bodies.
[0031] Specific Implementation Method Two: The difference between this implementation method and Specific Implementation Method One is that in step S1, when the bighead carp fry grow to a weight of 100-750g, the mortality rate of the bighead carp fry in water with different alkalinity values is measured within 12-96 hours.
[0032] The other steps are the same as in Specific Implementation Method 1.
[0033] Specific Implementation Method 3: The difference between this implementation method and Specific Implementation Method 1 or 2 is that when measuring the mortality rate of bighead carp fry in water with different alkalinity values within 12 to 96 hours in step S1, the water temperature is 20 to 23℃.
[0034] The other steps are the same as in Specific Implementation Method 1 or 2.
[0035] Specific Implementation Method Four: The difference between this implementation method and Specific Implementation Methods One to Three is that: in step S1, the safe concentration value of bighead carp fry within 12 to 96 hours is also calculated, and the safe concentration value is 1 to 17.72 mmol / L.
[0036] The other steps are the same as those in Specific Implementation Methods One to Three.
[0037] Specific Implementation Method 5: The difference between this implementation method and Specific Implementation Methods 1 to 4 is that the median lethal concentration of the bighead carp fry in step S1 is 57.761 to 89.668 mmol / L.
[0038] The other steps are the same as those in Specific Implementation Methods One through Four.
[0039] Specific Implementation Method Six: The difference between this implementation method and Specific Implementation Methods One to Five is that the alkalinity of the low-alkalinity pond water in step S2 is 10.0 to 15.0 mmol / L.
[0040] The other steps are the same as those in Specific Implementation Methods 1 to 5.
[0041] The beneficial effects of the present invention are verified using the following embodiments:
[0042] Example 1: A method for improving the survival rate of silver carp fry cultured in saline-alkali water, comprising the following steps:
[0043] Step S1: From May to September, according to the conventional artificial breeding techniques and methods for major freshwater fish, cultivate 1-year-old silver carp fry in freshwater ponds;
[0044] Step S2: In late September, when the silver carp fry grow to a weight of 117g at age 1, water bodies with alkalinity of 40mmol / L, 55mmol / L, 70mmol / L, 85mmol / L and 100mmol / L are prepared using chemically analytical grade NaHCO3.
[0045] Step S3: Collect 5-10 normal, healthy silver carp fry and conduct an experiment on the alkalinity tolerance of 1-year-old silver carp fry through three parallel trials:
[0046] Step S4: Observe and statistically analyze the mortality rate of experimental fish in each concentration group at different time points at 12h, 24h, 48h and 96h (see Table 1). The average fish weight was calculated to be 117g using the crown method commonly used in biotoxicology experiments. The water temperature was 20-23℃. The half-lethal alkalinity of the experimental fish at 96h was 57.7mmol / L (see Table 2).
[0047] Table 1 shows the mortality rate of 1-year-old silver carp at different time points in terms of alkalinity tolerance.
[0048] Table 1
[0049]
[0050] The procedure for calculating the median lethal concentration (LC50) using SPSS 27.00:
[0051] Taking the LC50 with a 96h rating as an example:
[0052] 1. For example Figure 3 As shown, after switching to "Variable View" in the lower left corner, define the variables and enter "Dosage", "Number of Fish", and "Number of Deaths" after the name. Then switch to "Data View" in the lower left corner and enter the data according to the table header.
[0053] 2. For example Figure 3As shown, in the main menu, go to "Analyze" → "Regression" → "Probability" to open the "Probability Analysis" dialog box. Select "Number of Deaths" in the "Response Frequency (S)" column, select "Number of Fish" in the "Total Measured Values (T)" column, select "Dose" in the "Covariate (C)" column, select "Logarithm to base 10" in the Transformation column, keep the other options at their default settings, and then click "OK" to output the data.
[0054] 3. For example Figure 4 As shown, in the output table, find the "Confidence Limit" column, where the probability is 0.500, which is LC50.
[0055] Table 2 shows the median lethal concentration and safe concentration for 1-year-old silver carp fry;
[0056] Table 2
[0057]
[0058] Step S5: Based on experimental data and production experience, determine that the maximum alkalinity value of the target water body for aquaculture, such as saline-alkali lakes and swamps, should not exceed 28.0 mmol / L.
[0059] In biological studies, during acute toxicological tolerance tests in animals, it is standard practice to determine the safe concentration and median lethal concentration (LD50) over a 96-hour period. The safe concentration is the concentration of a toxic substance that can be exposed to for a long period without producing adverse effects, while the LD50 is the concentration of a toxic substance that would cause death in half of the test animals.
[0060] In saline-alkali water aquaculture, to expand the aquaculture space, the salinity of the water used for stocking fish is generally higher than the safe concentration but lower than the 96-hour median lethal concentration. Extensive production experience and experimental data show that as long as the maximum alkalinity in saline-alkali water does not exceed half of the 96-hour median lethal concentration, fish mortality is unlikely, and they can grow normally. For example, the 96-hour median lethal concentration for silver carp is 64.19 mmol / L; in actual production, an alkalinity of no more than 32 mmol / L in the aquaculture water should be acceptable.
[0061] Therefore, based on the above experimental data and production experience, it is determined that the maximum alkalinity value of the water in which bighead carp fry can be cultured in saline-alkali water should not exceed 1 / 2 of the 96-hour half-lethal concentration, that is, the maximum alkalinity should not exceed 28.0 mmol / L. For bighead carp fry, this is considered a suitable alkalinity environment for culture.
[0062] Step S6: Set up fish adaptation and domestication ponds around saline-alkali lakes, swamps, etc., and prepare low-alkaline aquaculture water with a concentration of 10.0-15.0 mmol / L using river water and the saline-alkali water body of the aquaculture target.
[0063] Step S7: After harvesting the fish raised in freshwater ponds in September-October, they are first released into low-alkaline aquaculture ponds for 5-7 days for acclimatization and domestication, and then released into the target saline-alkali lakes, swamps and other water bodies for aquaculture.
[0064] Step S8: Experiments have shown that freshwater pond-raised fish fry that have not undergone acclimatization and are directly released into highly alkaline water (50 mmol / L) will exhibit intestinal edema after 24 hours (e.g., Figure 1 (as shown); after acclimatization in 15 mmol / L low-alkaline water for 5 days, and then placed in 50 mmol / L high-alkaline water, the intestines were normal after 24 hours, and no edema occurred in the intestinal tissue (as shown). Figure 2 (As shown)
[0065] Step S9: In high-salinity alkaline water with an alkalinity of 50 mmol / L, the fish fry were directly released without any acclimatization training, and the survival rate after 96 hours was 60%. However, after acclimatization training in low-alkaline water for 5 days, the survival rates after 96 hours were 100% for alkalinity of 15 mmol / L, 90% for alkalinity of 20 mmol / L, 50% for alkalinity of 30 mmol / L, and 50% for alkalinity of 40 mmol / L (see Table 3).
[0066] Table 3 shows the survival rate of 1-year-old bighead carp after acclimatization to low-alkaline water.
[0067] Table 3
[0068]
Claims
1. A method for improving the survival rate of silver carp fry cultured in saline-alkali water, characterized in that... This method is performed in the following steps: Step S1: Spring-bred silver carp fry were raised in freshwater ponds. In autumn or the following spring, when the silver carp fry reached 1 to 2 years of age, the mortality rate of the silver carp fry was measured at 12 h, 24 h, 48 h and 96 h in water with different alkalinity values at a water temperature of 20 to 23℃. Then, based on the mortality rate, the median lethal concentration (LD50) of the silver carp fry at 24 h, 48 h and 96 h was calculated, and half of the LD50 at 96 h was taken as the maximum alkalinity value for the silver carp fry to be cultured in saline-alkali water. In step S1, the safe concentration values of bighead carp fry within 24 h, 48 h, and 96 h were calculated, and the safe concentration value was 17.72 mmol / L for all of them; the median lethal concentration values of bighead carp fry at 96 h, 48 h, and 24 h in step S1 were 57.761 mmol / L, 77.974 mmol / L, and 89.668 mmol / L, respectively. Step S2: Before releasing the bighead carp fry cultivated in freshwater ponds into the target saline-alkali lakes or saline-alkali marshes, the bighead carp fry are first released into low-alkaline pond water for acclimatization. The alkalinity of the low-alkaline pond water is 1 / 3 to 1 / 2 of the maximum alkalinity value of the saline-alkali water aquaculture in step S1. Step S3: After the silver carp fry have been acclimatized in the low-alkaline pond water in step S2 for 5 to 7 days, they are then harvested and released into the target saline-alkali lake or saline-alkali marsh for further aquaculture.
2. The method for improving the survival rate of silver carp fry cultured in saline-alkali water according to claim 1, characterized in that... In step S1, when the silver carp fry grow to a weight of 100-750g, the mortality rate of the silver carp fry in water with different alkalinity values is measured within 12-96 hours.