The Chinese sturgeon is a large-scale anadromous fish. After the completion of the Gezhouba Water Control Project on the Yangtze River, it has a serious impact on Chinese sturgeon resources. The relevant competent authorities decided to adopt protective measures based on artificial reproduction and release, based on relevant data [1–3]. The broodstock of Phase 3 Chinese sturgeon, which is easy to capture in the dam section, is used to mature the gonads through artificial stocking, providing high-quality broodstock for Chinese sturgeon breeding.
1 Materials and Methods Preservation stage III Chinese sturgeons were all caught in the Lower Gezhouba section of the Gezhouba dam and were transported to the special storage tanks of the Institute. The area of ​​the storage ponds ranged from 80 to 250 m2. The water sources used river and well water, and the water quality indicators met the fishery water standards. .
All the stocked fish were weighed regularly by an electronic crane scale, and gonad tissue was punctured. The gonadal development status was examined by tissue section. It was determined that the artificial breeding was performed after reaching the end of the period IV. The artificial breeding and hatching was performed by a conventional method and was cultivated in a round pool of 2 m in diameter. During the experiment, leeches were used as baits, and the survival rate and growth rate were measured when they were grown to 9-10 cm.
2 Results and Discussion
2.1 Observe the development of female gonads
In October 1995, three females were captured and artificially stocked, numbered 95-102, 95-203, and 95-504. In order to study the gonadal development process of artificially stored Chinese sturgeon, they were in October 1995 and April 1996 respectively. In July and October, the eggs were punctured to check the gonadal development.
When entering the pool in October 1995, the average egg diameter of the two-tailed fish was 2.53 mm, and the average egg weight was 6.25 mg. The eggs were white or gray-white with an oblate shape. The slices showed that the nucleus was located at the center of the egg cell and the cytoplasm was uniformly distributed. Yolk granules, belong to the phase III oocytes (Plate I:1).
On April 20, 1996, the average egg diameter of two-tailed fish was 3.52 mm, and the egg weight was 18.69 mg. The egg color gradually darkened to gray-yellow, grayish-brown, oval-shaped oval, and a white dot was visible in the animal. Slices showed that the nucleus began to shift to the center and moved towards the animal pole. The distribution of yolk particles in the cytoplasm was not uniform, the plant yolk granules appeared slightly larger, the animal yolk granules were slightly smaller, and belonged to the phase III at phase III. The transition type of mother cells (Plate I: 2).
On July 10, 1996, the average egg diameter was 4.02 mm, the egg weight average was 28.19 mg, and the egg color further darkened to brown. The animal showed a very faint polar pattern and the oval shape was similar to an ellipse. The slices showed that the nucleus was significantly shifted. In the center, the polarization of the cytoplasm is obvious. The animal yolk distributes tiny yolk granules, and the yolk granules of the plant are greatly enlarged, belonging to the oocytes of the early phase IV (Plate I:3).
In October 1996, the average egg diameter of the three-tailed fish was 4.63mm, and the average egg weight was 41.26mg. The egg color changed to brown, full and elastic, and the polar spot was obvious. Slices showed that the nuclear was close to the animal pole membrane and the degree of egg polarization was At its maximum, the animal has a dense matrix and fine yolk granules on one end, and a large yolk granule on one end of the plant, belonging to the oocytes at the end of the fourth phase (Plate I:4).
Phase III ovary development of Chinese sturgeon is a gradual and gradual change to stage IV ovarian development. With the accumulation of nutrients, egg cells gradually grow and the nucleus moves towards the animal pole. When the nucleus approaches the animal pole membrane, stage IV is completed. development.
2.2 Observing the gonadal development of male and female aphids Due to the limitations of the material, only two conditions were observed when entering the pool in October of that year and going out of the pool in October of the following year. When entering the pool, a section of the testis tissue was removed by puncture in gray, thick cords; The testis tissue is composed of a number of sperm vesicles. Primary spermatocytes, secondary spermatocytes, and a small number of sperm cells are sequentially distributed in the sperm vesicles (Figure I:5); After oxytocin production, the testis is plump, milky white, and the volume is significantly increased. The adipose tissue attached to the testis disappears. Slices show that in addition to a small amount of spermatocytes and sperm cells, sperm vesicles contain large amounts of vortex-like sperm. At the time of defecation, it is the Vth testis (Plate I:6).
2.3 Artificial propagation and fry cultivation of Chinese sturgeon
In October 1990 and October 1991, the mature males of two stocks, 89-501 and 90-301, respectively, were treated with LRH?A and spawned 2200ml and 2600ml respectively. The sperm life was 5′10′′ and 6′ respectively. 30′′, fertilized with natural mature eggs, the fertilization rates were 86% and 89%, respectively.
In October 1996, 95-102 and 95-203 of the mature female three-tailed females were elicited with LRH?A, of which 95-102 were born spontaneously, and 629,000 were spawned. Fertilization with naturally matured male fleas (life is 3 years) The fertility rate of '35'') was 46.9%, the hatching rate was 82.4%, and 250,000 seedlings emerged. The other end was half-produced due to small doses and there was no artificial insemination; the other mature 95-504 was dissected and the fish was Total weight 180.5kg, shell weight 139kg, fish body weight loss, body fat layer is thin, no food in the digestive tract, internal organs without disease symptoms, ovarian brown, full egg, ovarian gross weight 38.2kg, maturity coefficient is 27.48%, The absolute fertility of 536,000 grains, ovarian development is in good condition.
The 250,000 seedlings hatched released 235,000 tails on October 24, 1996, leaving 15,000 tails for cultivation. The incubation time was from October 17 to December 5, which lasted 49 days. No abnormalities were found during the incubation period. The survival rate was 74%, the survival rate was 68%, and the survival rate was 50.3%. The growth of the young larvae was good. When the water temperature was 20-23°C, the total growth was 1.85mm/d, and the body weight was increased by 60mg/d. Approximately 7,500 pups of 9-10 mg in total length were released and released on the Yangtze River on December 5.
Through artificial stocking, the gonads of Chinese sturgeon develop from stage III to stage IV, and they are successfully propagated artificially. This will promote the artificial release of Chinese sturgeon and the development of the aquaculture industry. It has a good application prospect and provides stable high quality for artificial propagation. The mature broodstock is easy to obtain because it is used for stocking, and it is not limited by the fishing period. Artificial stocking can avoid the adverse environmental and water pollution, and is more conducive to gonadal development; stocking can be propagated about half a month in advance, extending the Artificial breeding time is conducive to the expansion of scale and cost savings. In addition, it has made necessary technical preparations for saving fish in the Three Gorges Water Control Project.
1 Materials and Methods Preservation stage III Chinese sturgeons were all caught in the Lower Gezhouba section of the Gezhouba dam and were transported to the special storage tanks of the Institute. The area of ​​the storage ponds ranged from 80 to 250 m2. The water sources used river and well water, and the water quality indicators met the fishery water standards. .
All the stocked fish were weighed regularly by an electronic crane scale, and gonad tissue was punctured. The gonadal development status was examined by tissue section. It was determined that the artificial breeding was performed after reaching the end of the period IV. The artificial breeding and hatching was performed by a conventional method and was cultivated in a round pool of 2 m in diameter. During the experiment, leeches were used as baits, and the survival rate and growth rate were measured when they were grown to 9-10 cm.
2 Results and Discussion
2.1 Observe the development of female gonads
In October 1995, three females were captured and artificially stocked, numbered 95-102, 95-203, and 95-504. In order to study the gonadal development process of artificially stored Chinese sturgeon, they were in October 1995 and April 1996 respectively. In July and October, the eggs were punctured to check the gonadal development.
When entering the pool in October 1995, the average egg diameter of the two-tailed fish was 2.53 mm, and the average egg weight was 6.25 mg. The eggs were white or gray-white with an oblate shape. The slices showed that the nucleus was located at the center of the egg cell and the cytoplasm was uniformly distributed. Yolk granules, belong to the phase III oocytes (Plate I:1).
On April 20, 1996, the average egg diameter of two-tailed fish was 3.52 mm, and the egg weight was 18.69 mg. The egg color gradually darkened to gray-yellow, grayish-brown, oval-shaped oval, and a white dot was visible in the animal. Slices showed that the nucleus began to shift to the center and moved towards the animal pole. The distribution of yolk particles in the cytoplasm was not uniform, the plant yolk granules appeared slightly larger, the animal yolk granules were slightly smaller, and belonged to the phase III at phase III. The transition type of mother cells (Plate I: 2).
On July 10, 1996, the average egg diameter was 4.02 mm, the egg weight average was 28.19 mg, and the egg color further darkened to brown. The animal showed a very faint polar pattern and the oval shape was similar to an ellipse. The slices showed that the nucleus was significantly shifted. In the center, the polarization of the cytoplasm is obvious. The animal yolk distributes tiny yolk granules, and the yolk granules of the plant are greatly enlarged, belonging to the oocytes of the early phase IV (Plate I:3).
In October 1996, the average egg diameter of the three-tailed fish was 4.63mm, and the average egg weight was 41.26mg. The egg color changed to brown, full and elastic, and the polar spot was obvious. Slices showed that the nuclear was close to the animal pole membrane and the degree of egg polarization was At its maximum, the animal has a dense matrix and fine yolk granules on one end, and a large yolk granule on one end of the plant, belonging to the oocytes at the end of the fourth phase (Plate I:4).
Phase III ovary development of Chinese sturgeon is a gradual and gradual change to stage IV ovarian development. With the accumulation of nutrients, egg cells gradually grow and the nucleus moves towards the animal pole. When the nucleus approaches the animal pole membrane, stage IV is completed. development.
2.2 Observing the gonadal development of male and female aphids Due to the limitations of the material, only two conditions were observed when entering the pool in October of that year and going out of the pool in October of the following year. When entering the pool, a section of the testis tissue was removed by puncture in gray, thick cords; The testis tissue is composed of a number of sperm vesicles. Primary spermatocytes, secondary spermatocytes, and a small number of sperm cells are sequentially distributed in the sperm vesicles (Figure I:5); After oxytocin production, the testis is plump, milky white, and the volume is significantly increased. The adipose tissue attached to the testis disappears. Slices show that in addition to a small amount of spermatocytes and sperm cells, sperm vesicles contain large amounts of vortex-like sperm. At the time of defecation, it is the Vth testis (Plate I:6).
2.3 Artificial propagation and fry cultivation of Chinese sturgeon
In October 1990 and October 1991, the mature males of two stocks, 89-501 and 90-301, respectively, were treated with LRH?A and spawned 2200ml and 2600ml respectively. The sperm life was 5′10′′ and 6′ respectively. 30′′, fertilized with natural mature eggs, the fertilization rates were 86% and 89%, respectively.
In October 1996, 95-102 and 95-203 of the mature female three-tailed females were elicited with LRH?A, of which 95-102 were born spontaneously, and 629,000 were spawned. Fertilization with naturally matured male fleas (life is 3 years) The fertility rate of '35'') was 46.9%, the hatching rate was 82.4%, and 250,000 seedlings emerged. The other end was half-produced due to small doses and there was no artificial insemination; the other mature 95-504 was dissected and the fish was Total weight 180.5kg, shell weight 139kg, fish body weight loss, body fat layer is thin, no food in the digestive tract, internal organs without disease symptoms, ovarian brown, full egg, ovarian gross weight 38.2kg, maturity coefficient is 27.48%, The absolute fertility of 536,000 grains, ovarian development is in good condition.
The 250,000 seedlings hatched released 235,000 tails on October 24, 1996, leaving 15,000 tails for cultivation. The incubation time was from October 17 to December 5, which lasted 49 days. No abnormalities were found during the incubation period. The survival rate was 74%, the survival rate was 68%, and the survival rate was 50.3%. The growth of the young larvae was good. When the water temperature was 20-23°C, the total growth was 1.85mm/d, and the body weight was increased by 60mg/d. Approximately 7,500 pups of 9-10 mg in total length were released and released on the Yangtze River on December 5.
Through artificial stocking, the gonads of Chinese sturgeon develop from stage III to stage IV, and they are successfully propagated artificially. This will promote the artificial release of Chinese sturgeon and the development of the aquaculture industry. It has a good application prospect and provides stable high quality for artificial propagation. The mature broodstock is easy to obtain because it is used for stocking, and it is not limited by the fishing period. Artificial stocking can avoid the adverse environmental and water pollution, and is more conducive to gonadal development; stocking can be propagated about half a month in advance, extending the Artificial breeding time is conducive to the expansion of scale and cost savings. In addition, it has made necessary technical preparations for saving fish in the Three Gorges Water Control Project.
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