CN100370896C - Breeding method of broodstock of half-smooth tongue sole - Google Patents

Abstract

The invention provides a broodstock breeding method of semi-smooth tongue sole, which solves the domestication problem of the broodstock by controlling the hydrological environment factors of the broodstock breeding; solves the overwintering problem of the broodstock by controlling the growth environment conditions of the broodstock; and solves the gonad development problem of the broodstock by controlling changes in light and water temperature. Through the implementation of the present invention, the gonads of the parent fish are mature, and the abdomen is obviously protruding; the protruding part of the ventral surface is lightly stroked with hands, and the gonads of the parent fish are clearly felt to be in a soft state, and 100% of the parent fish gonads are mature. It takes 50 days to reach the development level of nearly 4 months under natural conditions; 100% of the female fish gonads are guaranteed to develop normally and fertilize eggs. The results of the two-year repeated overwintering test of broodstock showed that the survival rate of broodstock overwintering was 100%. The broodstock is in good health, the body color is darker than the broodstock in the natural sea area, and no diseases and parasites have been found.

Description

Breeding method of broodstock of half-smooth tongue sole

technical field

The invention relates to an artificial propagation method of Soleidae fish, in particular to an artificial propagation method of half-smooth tongue sole. It belongs to the field of aquaculture in marine engineering.

Background technique

Semi-smooth tongue sole (Cynoglossus semilaevis Gunther) belongs to the flatfish order, Cynoglossus semilaevis family. Because of its tender meat and delicious taste, it is loved by consumers and is a rare fish species with high economic value. Semi-smooth tongue sole inhabits the coastal waters of my country all year round. It has the characteristics of wide temperature, wide salt and low food level. It is considered to be one of the ideal fish species for breeding and multiplication. Its large-scale production has received great attention from all aspects of society.

The reproductive habits of tongue sole have the following main characteristics: First, in different seasons, the sex ratio of natural populations of tongue sole in a certain area varies greatly. In general, the sex ratio of the population is: ♀:♂=61:39. The sex ratio also varies significantly with the degree of gonad development. Before spawning (before mid-August), the female fish in the reproductive group is absolutely dominant, with a sex ratio of ♀:♂=4:1; after mid-August, the number of male fish gradually increases, and the ratio of male to female fish is ♀:♂=2: 1. In the first ten days of September, the ontogeny gonads mature, and during the entire spawning period, female fish account for 55% and male fish account for 45%, which is more obvious than other marine bony fishes. The second feature is that there is a significant difference in the size of male and female individuals. Fully mature individuals can be clearly divided into two body length groups, female and male. The body length of female fish exceeds 390mm; the body length of male fish ranges from 180mm-380mm. In the entire spawning population, the maximum body length of female fish is 735mm; the minimum body length is 490mm; the average body length is 523mm, and the maximum body length of male fish is 420mm; the minimum body length is only 198mm, and the average body length is 280mm. The third feature is that the male and female gonads are very different: the ovaries of half-smooth tongue sole are extremely developed, but the testes are extremely underdeveloped. Females have a high egg count. For individuals with a body length of 560-700m, the egg count is as high as 760,000 to 2.5 million eggs, and most individuals have about 1.5 million eggs. The difference between male and female gonads leads to low egg fertilization rate and high mortality in natural sea areas. In addition, the undomesticated fish species have a short survival time after being separated from the natural environment, and are not suitable for live storage and transportation.

In addition, half-smooth tongue soles do not cluster strongly in natural sea areas, nor do they cluster during spawning, resulting in relatively scattered spawning grounds.

Although many domestic and foreign scientific research institutions, colleges, and enterprises have conducted artificial breeding experiments of semi-smooth tongue sole in different scales and degrees, they have not obtained satisfactory results due to insufficient understanding of the fish's ecological, physiological and other biological characteristics. , the large-scale production of semi-smooth tongue sole has been elusive.

Contents of the invention

The technical problem to be solved by the present invention is to provide a broodstock breeding method of semi-smooth tongue sole, solve the domestication problem of broodstock by controlling the hydrological environment factors of broodstock cultivation; solve the overwintering problem of broodstock by controlling the growth environment conditions of broodstock; solve the problem of broodstock by controlling changes in light and water temperature Gonadal development problems.

In order to solve the above problems, the present invention adopts the following technical solutions.

A method for cultivating broodstock of half-smooth tongue sole, characterized in that: during the pre-culture of broodstock, environmental factors include: water temperature 26.2-18.4°C; salinity 26.20-30.60‰; Ph7.7-8.6; dissolved oxygen 6.5-9.5mg/l; The ratio is male to female = 1:3;

Broodstock overwintering, that is, when the natural water temperature of seawater is below 12°C: the water used is a mixture of underground brine and fresh water, so that the water quality factor ranges: salinity 28.55-29.15‰, pH 7.6, dissolved oxygen 8mg/l, temperature 15.3-16.8°C ;

During gonad development of broodstock: the water temperature is gradually increased from 18°C to 24°C, and the daily temperature rise does not exceed 0.2°C, and 60 days is a temperature control cycle; the light time is gradually increased from 6 hours/day to 12 hours/day, and the light time is extended every day. More than 72 minutes, 5 days is a light control period, and the light intensity is 5001ux.

The values of water temperature, salinity, pH, dissolved oxygen 8mg/l, and sex ratio are all key points of the present invention, and are obtained through several experimental studies. If the water temperature is too low, the broodstock will eat less food, and if the water temperature is too high, it will induce diseases. Broodstock cannot survive if the salinity is lower than 12‰, and if the salinity is too high, the growth will be slow. If the pH value is too low, the disease rate is high, and if the pH value is too high, the survival rate of broodstock will decrease. When the dissolved oxygen is lower than the lower limit, the broodstock is in an unfavorable anoxic state. If the dissolved oxygen is greater than the upper limit, not only the reproduction cost is too high, but also the broodstock has a higher probability of air bubble disease.

The temperature control and light control technology during the gonad development of broodstock is another key creative point of the present invention. The gradual change of temperature and light time simulates the natural environmental conditions and is more suitable for the reproduction of this type of fish species. The variation range of temperature and light time is also determined through several experimental studies.

Through the implementation of this scheme, the gonads of the broodstock are mature, and the abdomen is obviously protruding; the protruding part of the ventral surface is lightly stroked with hands, and the gonads are obviously soft, and 100% of the broodstock gonads are mature. It takes 50 days to reach the development level of nearly 4 months under natural conditions; 100% of the female fish gonads are guaranteed to develop normally and fertilize eggs.

The results of the two-year repeated overwintering test of broodstock showed that the survival rate of broodstock overwintering was 100%. The broodstock is in good health, the body color is darker than the broodstock in the natural sea area, and no diseases and parasites have been found.

Detailed ways

The general cement pond (6.0×4.0×1.5m) was used as broodstock breeding and overwintering pond. The pre-treated sediment is laid on the bottom of the pool to form an artificial seabed. The sediment is sun-dried and sieved, the ratio of sand to mud is 3:1, and the thickness is 20-30cm. A water flow regulator and a water flow circulation pipeline are installed at the drain hole at the bottom of the pool. The inner diameters of the double pipes are 20cm and 14cm respectively, and the height is 165cm. The water flow rate is adjusted within the range of 20-48L/min. Before broodstock enter the pool, soak and rinse until the pH of the pool water drops below 8.6.

During broodstock cultivation, the line is intermittently inflated. The air stones are distributed near the bottom layer to avoid stirring the sediment when aerating. Other environmental factors include: water temperature 26.2-18.4°C; salinity 26.20-30.60‰; Ph 7.7-8.6; dissolved oxygen 6.5-9.5mg/l; stocking density of broodstock 4-6 fish/pond, sex ratio ♀: ♂=1:3.

During broodstock management, (1) monitor various environmental factors regularly to keep each factor within the optimum range. (2) Maintain clean water quality. Maintain a circulating water body. The daily water change rate is over 100%. It is advisable to keep the water until the bottom of the pool can be seen clearly, remove residual bait, dirt and dead fish. Check the survival rate of broodstock before injecting fresh seawater, observe the degree of gonad development and feeding situation, and make records. (3) Ensure sufficient bait supply. Feed 2 times a day. The feeding amount is about 3-5% of the body weight of the broodstock. The main types of bait are lugworm, mantis shrimp and variegated clam meat, followed by small miscellaneous fish. The newly caught broodstock usually refuses to eat, and individual broodstock refuses to eat until they starve to death. The larger the individual, the longer the food refusal duration, and the female broodstock refusal to eat longer than the male. Feed more at night than during the day.

In order to protect the precious species resources of tongue sole and obtain sufficient fertilized eggs, we conducted a wintering experiment of broodstock of tongue sole. During the experiment, the gonad development rule and spawning mechanism of this fish species were further explored.

In Bohai Bay, in mid-November, the water temperature drops below 12°C, and broodstock begin to enter the wintering period.

The water for broodstock overwintering is a mixture of underground brine (salinity 84‰, temperature 16.0-18.0°C; PH7.6) and fresh water, so that the range of water quality factors can reach: salinity 28.55-29.15‰, PH7.6, dissolved oxygen 8mg/l , temperature 15.3-16.8°C.

From the beginning of overwintering, natural seawater is used to cultivate overwintering broodstock. During the cultivation process, gradually increase the ratio of artificially mixed water with brine and fresh water. After half a month, all the water for cultivation was replaced with artificially mixed brine. The water temperature of the overwintering pool is maintained within the range of 15.3-16.8°C. In late February of the following year, as the temperature rose, the water temperature of the overwintering pool was gradually increased. When the sea water temperature rises to 12.0°C, the broodstock breeding water gradually increases the proportion of natural seawater until all the water is converted to natural seawater.

The inflation of broodstock overwintering pool is discontinuous inflation, every morning and evening ventilate 1 hour. Change the water every 2-3 days. When changing the water, observe the activity, health status and feeding status of the broodstock. Remove residual bait and dirt in time to keep the water clean. Regularly put 1-2ppm antibiotics to prevent the emergence of infectious diseases.

The bait for overwintering broodstock is mainly frozen variegated clams, and clams and frozen miscellaneous fish are secondary. The feeding amount is 2-3% of the body weight of the broodstock.

The selected male and female broodstock are mixed in a cement pond according to the proportion. After a period of careful feeding and fattening, after reaching the ideal state, refer to the basic law of gonad development of the fish in the natural sea area and the relevant biological characteristics. A unique set of temperature control and light control methods that are different from other flatfish species. Focus on temperature, supplemented by light. The specific measures are: gradually increase the water temperature from 18°C to 24°C, and the daily temperature rise does not exceed 0.2°C. 60 days is a temperature control cycle; the light time is gradually increased from 6 hours/day to 12 hours / day, the light time should not be extended for more than 72 minutes every day, and 5 days is a light control cycle. The key points of this technology include: determining the start-up point of regulation by the stage of gonad development and temperature; sequentially changing light and temperature treatment parameters and treatment time schedule.

Claims (1)

1. the parent fish rearing method of a Cynoglossus semilaevis is characterized in that: between parent population culture period in early stage, envirment factor comprises: water temperature 26.2-18.4 ℃; Salinity 26.20-30.60 ‰; Ph7.7-8.6; Dissolved oxygen 6.5-9.5mg/l; The property than comparing=1: 3 for male and female;

Parent fish live through the winter, when promptly the seawater natural temperature was below 12 ℃: water was the mixing water of subsurface brine and fresh water, the water quality factor scope is reached: salinity 28.55-29.15 ‰, PH7.6, dissolved oxygen 8mg/l, temperature 15.3-16.8 ℃;

During the parent population gonad development: water temperature is brought up to 24 ℃ gradually by 18 ℃, and every day, intensification was no more than 0.2 ℃, and 60 days is a temperature control cycle; Light application time was brought up to 12 hours/day gradually by 6 hours/day, prolonged light application time every day and was no more than 72 minutes, and 5 days is a control photoperiod, and intensity of illumination is being 500lux.