First, materials and methods
1. Test conditions The experiment was conducted in a shrimp nursery room in Nantang Town, Yueqing City, Zhejiang Province. The test water body was 600 cubic meters, including 400 cubic meters of water for nursery and a total of 10 identical cultivation ponds. The bait cultivates 200 cubic meters of water, altogether 20 breeding ponds. The water supply system adopts secondary sedimentation and water supply through the high-level pond sand filter. Two Roots blowers were used to rotate continuously and the gas stones were evenly placed at the bottom of the pool and were frequently adjusted to maintain even air-inflating. Indoor light control is 800 to 1000 lux, salinity is 24 to 26, water temperature is 28 to 32°C, and pH is 8.2 to 8.6.
2. Test methods (1) Breeding. The pro-be used for the experiment was collected from the sea near Nantang Town, Yueqing City. In April, it was moved into the outdoor earthen ponds for fattening by means of feeding or changing water. A total of 10 kilograms of pro-Belle were raised in an earthen pond of 5 acres. During the holding period, depending on the water quality, the water is exchanged between 1/4 and 1/3 a day, inoculated with gold algae and Platymonas, and the density of unicellular algae in the water body is maintained. In late June, 5 to 7 days before spawning, it is moved to the indoor cement pool for intensive cultivation. It is inflated and changed water 1/3 to 1/2 per day. The amount of feeding is 150,000 cells/ml. The incubation temperature is 24 to 26°C. .
(2) Spawning hatching. When examining the development of pro-glandular glands, when most of the individual's gonads are mature, select 15 kg of individuals with a robust body and a shell length of 2.5 cm or longer to wash and disinfect, and then rinse with 5 to 10 g/m 3 of potassium permanganate for 10 minutes. Four hours after the shade was dried, the parent crabs were evenly spread on a rectangular spawning bed woven with bamboo strips and placed flat on the bottom of the spawning pool. The spawning bed size is 1.5 meters and 1.0 meters. Open the inlet valve and drain valve of the hatching tank, and use the water pump to flush water horizontally into the wall of the inlet, so that the water flows evenly through the egg-laying bed to stimulate the pro-shellfish. After the pro-Bet emission of eggs, lift the egg-laying bed up to about 20 cm from the water surface and pick out male individuals in time to reduce excess semen. After the discharge is completed, the egg-laying bed will be removed, the pool water will be filled, and left standing for about 30 minutes. The egg washing hole and siphon will be used to drain the upper layer of water to wash eggs, and excess semen and dead eggs will be discharged to ensure that the hatching water is clean.
(3) larvae reared. Before pro-shellworm spawning, the hatching pool was sterilized with 20,000 international units of penicillin and 40,000 international units of streptomycin, then filled with water and inflated. After the eggs were washed, the fertilized eggs were transferred to hatching pond for hatching. The hatching density is controlled at 30-40/ml.
When the larvae develop into platter larvae, larvae breeding and sizing are started. The upper sturdy and lively larvae are further incubated with a 300-mesh net in a culturing pond after disinfection and incubating, and the culturing density is 5-8 per ml. When the intestines of the larvae are formed and the digestive organs are well developed, they are fed with bait. The forked chlorella and Isochrysis galbana are used as the open bait. Each time the water is changed, the daily feeding amount is 20,000 cells/ml. As the individual's growth and feeding amount and algae species gradually increased, C. reesei, Z. algae, Platymonas, and chlorella were mixed and fed. The daily feeding amount of larvae after perennial attachment increased to 50,000-60,000 cells/ml to increase the larvae's demand for various nutrients. When the food is insufficient, it is supplemented with a small amount of active yeast.
When the larvae reach the metamorphosis stage, the beach mud scraped off in the nearby sea area, which has been scraped off and treated and screened, is used as the attachment base. The larvae are bred to the attachment pool and cultivated to the juveniles. The cultivation density is 800,000 to 1 million pieces/square meter.
In the early stage of larvae, 10 cm of water is added every day. With the increase of individuals, the water is changed by 1/2 per day, and the amount of water changed to 2/3 per day during the top of the shell, and the amount of water changed from 100% to 300% after the larvae are transferred to benthic life. .
Second, the results
1. Selection and cultivation of pro-shellworms 3 months before breeding, choose 2 to 3 years old loach with high fatness and good gonadal development for conservation in the outdoor soil pool, and increase fertilization by feeding and changing water. Fullness and gonadal maturity. When the progozoa's gonadal maturity reaches the discharge period of 5 to 7 days, it is moved to the indoor concrete pool for inflating and feeding for intensive cultivation. Observed continuously with the mud louse collected in the natural sea area, the fertility and gonad maturation degree of the pro-scallops after being raised and intensified were significantly better than those of pro-shellfish collected in the natural sea area.
2. Spawning hatching In order to keep the water clean, the dried shellfish were evenly spread on a rectangular spawning bed woven with bamboo strips to stimulate water flow. After 20 minutes, the progeny began to emit sperm and eggs, and the male semen was white silk. Cocoon-like, female eggs slowly exhale as pale yellow smoke. Pick male individuals on time to reduce excess semen. Emission duration is about 40 minutes. The fertility-producing pro-shellfish spawning rate is about 37%, and the average individual egg production is 2.5 million. At the end of the discharge, the egg-laying bed was removed and allowed to stand for about 30 minutes to precipitate the eggs. Use egg-washing drainage holes and siphon to drain the upper layer of water, and then fill the pool with water, wash the eggs twice and remove excess semen and egg fluid. Open the air valve, adjust the amount of air bubbles and aeration, and make the water quality meet the requirements for incubating water. The hatching density of each pool was controlled at 30-40/ml. At a water temperature of 30 to 32°C and a salinity of 24 to 26, the first polar body appeared 9 minutes after the fertilized egg and developed into the platy larvae at 16 hours. The average fertilization rate was 98%, and the average hatch rate was 89%.
3. The larval reared the larvae for approximately 14 days to develop the eyeballs to the metamorphosis stage and started to attach the attachment base. The beach mud is scraped on the muddy growth sea area beach surface, boiled and sterilized and then filtered through a sieve mesh (with a particle size of 50 to 100 microns). The pool is evenly laid on the bottom of the pool, and the water is poured to stop the aeration. After the precipitation, the small amount of gas is inflated, and the amount of gas is preferably not to stir the sediment. The larvae were transferred to the attachment pool with a 300-mesh sieve and the water exchange volume and feed amount were increased. The daily water exchange volume is 100% to 300%, and the daily feeding amount is maintained at 40,000 to 60,000 cells/ml. After larvae develop into juveniles, they are poured once every 5 days. The survival rate of the platter larvae to metamorphosis was 69%, and the adherence rate was 35%. Out of 650 to 950 millimeters of juveniles, 609,000 grains/m2, juveniles are cultivated to an area of ​​300 square meters, and the total seedling volume is 180 million grains.
Third, discussion and summary
1. The conservation and cultivation of pro-shellfish is an important technical link for shellfish breeding. Artificial feeding and changing of water are some of the measures. Intensive breeding of pro-scallops is promoted in advance to promote the development of pro-lactophilic gonads and a large number of quality eggs can be obtained. It is an effective measure to increase spawning rate and hatching rate.
2. The use of spawning beds to mobilize can adjust the height according to need, pick out male individuals in time, reduce the semen in the water body, remove pro-shelled Fish at one time, and prevent water pollution.
3. Under the production conditions, using the egg washing hole and siphon to discharge the upper layer of water can also achieve the effect of washing eggs repeatedly and repeatedly, especially when large areas are used for breeding to avoid egg damage.
4. Feed is an important factor affecting the development of juveniles. Poor feeding or a single feed can cause slow growth of larvae. Individual development is uneven. Due to lack of nutrition, not only the survival rate is low, but also susceptible to disease. All kinds of bait are mixed and fed, and keeping the density of monocytic algae in the water at any time is an effective measure to improve the survival rate of nursery.
5. Loach larvae have higher requirements on water quality, increase the amount of water exchange, and reduce the content of organic matter such as residual baits and feces in the water, which can promote the growth and development of larvae and increase the survival rate.
Author: Dandong Fisheries Technology Extension Station, Liaoning
1. Test conditions The experiment was conducted in a shrimp nursery room in Nantang Town, Yueqing City, Zhejiang Province. The test water body was 600 cubic meters, including 400 cubic meters of water for nursery and a total of 10 identical cultivation ponds. The bait cultivates 200 cubic meters of water, altogether 20 breeding ponds. The water supply system adopts secondary sedimentation and water supply through the high-level pond sand filter. Two Roots blowers were used to rotate continuously and the gas stones were evenly placed at the bottom of the pool and were frequently adjusted to maintain even air-inflating. Indoor light control is 800 to 1000 lux, salinity is 24 to 26, water temperature is 28 to 32°C, and pH is 8.2 to 8.6.
2. Test methods (1) Breeding. The pro-be used for the experiment was collected from the sea near Nantang Town, Yueqing City. In April, it was moved into the outdoor earthen ponds for fattening by means of feeding or changing water. A total of 10 kilograms of pro-Belle were raised in an earthen pond of 5 acres. During the holding period, depending on the water quality, the water is exchanged between 1/4 and 1/3 a day, inoculated with gold algae and Platymonas, and the density of unicellular algae in the water body is maintained. In late June, 5 to 7 days before spawning, it is moved to the indoor cement pool for intensive cultivation. It is inflated and changed water 1/3 to 1/2 per day. The amount of feeding is 150,000 cells/ml. The incubation temperature is 24 to 26°C. .
(2) Spawning hatching. When examining the development of pro-glandular glands, when most of the individual's gonads are mature, select 15 kg of individuals with a robust body and a shell length of 2.5 cm or longer to wash and disinfect, and then rinse with 5 to 10 g/m 3 of potassium permanganate for 10 minutes. Four hours after the shade was dried, the parent crabs were evenly spread on a rectangular spawning bed woven with bamboo strips and placed flat on the bottom of the spawning pool. The spawning bed size is 1.5 meters and 1.0 meters. Open the inlet valve and drain valve of the hatching tank, and use the water pump to flush water horizontally into the wall of the inlet, so that the water flows evenly through the egg-laying bed to stimulate the pro-shellfish. After the pro-Bet emission of eggs, lift the egg-laying bed up to about 20 cm from the water surface and pick out male individuals in time to reduce excess semen. After the discharge is completed, the egg-laying bed will be removed, the pool water will be filled, and left standing for about 30 minutes. The egg washing hole and siphon will be used to drain the upper layer of water to wash eggs, and excess semen and dead eggs will be discharged to ensure that the hatching water is clean.
(3) larvae reared. Before pro-shellworm spawning, the hatching pool was sterilized with 20,000 international units of penicillin and 40,000 international units of streptomycin, then filled with water and inflated. After the eggs were washed, the fertilized eggs were transferred to hatching pond for hatching. The hatching density is controlled at 30-40/ml.
When the larvae develop into platter larvae, larvae breeding and sizing are started. The upper sturdy and lively larvae are further incubated with a 300-mesh net in a culturing pond after disinfection and incubating, and the culturing density is 5-8 per ml. When the intestines of the larvae are formed and the digestive organs are well developed, they are fed with bait. The forked chlorella and Isochrysis galbana are used as the open bait. Each time the water is changed, the daily feeding amount is 20,000 cells/ml. As the individual's growth and feeding amount and algae species gradually increased, C. reesei, Z. algae, Platymonas, and chlorella were mixed and fed. The daily feeding amount of larvae after perennial attachment increased to 50,000-60,000 cells/ml to increase the larvae's demand for various nutrients. When the food is insufficient, it is supplemented with a small amount of active yeast.
When the larvae reach the metamorphosis stage, the beach mud scraped off in the nearby sea area, which has been scraped off and treated and screened, is used as the attachment base. The larvae are bred to the attachment pool and cultivated to the juveniles. The cultivation density is 800,000 to 1 million pieces/square meter.
In the early stage of larvae, 10 cm of water is added every day. With the increase of individuals, the water is changed by 1/2 per day, and the amount of water changed to 2/3 per day during the top of the shell, and the amount of water changed from 100% to 300% after the larvae are transferred to benthic life. .
Second, the results
1. Selection and cultivation of pro-shellworms 3 months before breeding, choose 2 to 3 years old loach with high fatness and good gonadal development for conservation in the outdoor soil pool, and increase fertilization by feeding and changing water. Fullness and gonadal maturity. When the progozoa's gonadal maturity reaches the discharge period of 5 to 7 days, it is moved to the indoor concrete pool for inflating and feeding for intensive cultivation. Observed continuously with the mud louse collected in the natural sea area, the fertility and gonad maturation degree of the pro-scallops after being raised and intensified were significantly better than those of pro-shellfish collected in the natural sea area.
2. Spawning hatching In order to keep the water clean, the dried shellfish were evenly spread on a rectangular spawning bed woven with bamboo strips to stimulate water flow. After 20 minutes, the progeny began to emit sperm and eggs, and the male semen was white silk. Cocoon-like, female eggs slowly exhale as pale yellow smoke. Pick male individuals on time to reduce excess semen. Emission duration is about 40 minutes. The fertility-producing pro-shellfish spawning rate is about 37%, and the average individual egg production is 2.5 million. At the end of the discharge, the egg-laying bed was removed and allowed to stand for about 30 minutes to precipitate the eggs. Use egg-washing drainage holes and siphon to drain the upper layer of water, and then fill the pool with water, wash the eggs twice and remove excess semen and egg fluid. Open the air valve, adjust the amount of air bubbles and aeration, and make the water quality meet the requirements for incubating water. The hatching density of each pool was controlled at 30-40/ml. At a water temperature of 30 to 32°C and a salinity of 24 to 26, the first polar body appeared 9 minutes after the fertilized egg and developed into the platy larvae at 16 hours. The average fertilization rate was 98%, and the average hatch rate was 89%.
3. The larval reared the larvae for approximately 14 days to develop the eyeballs to the metamorphosis stage and started to attach the attachment base. The beach mud is scraped on the muddy growth sea area beach surface, boiled and sterilized and then filtered through a sieve mesh (with a particle size of 50 to 100 microns). The pool is evenly laid on the bottom of the pool, and the water is poured to stop the aeration. After the precipitation, the small amount of gas is inflated, and the amount of gas is preferably not to stir the sediment. The larvae were transferred to the attachment pool with a 300-mesh sieve and the water exchange volume and feed amount were increased. The daily water exchange volume is 100% to 300%, and the daily feeding amount is maintained at 40,000 to 60,000 cells/ml. After larvae develop into juveniles, they are poured once every 5 days. The survival rate of the platter larvae to metamorphosis was 69%, and the adherence rate was 35%. Out of 650 to 950 millimeters of juveniles, 609,000 grains/m2, juveniles are cultivated to an area of ​​300 square meters, and the total seedling volume is 180 million grains.
Third, discussion and summary
1. The conservation and cultivation of pro-shellfish is an important technical link for shellfish breeding. Artificial feeding and changing of water are some of the measures. Intensive breeding of pro-scallops is promoted in advance to promote the development of pro-lactophilic gonads and a large number of quality eggs can be obtained. It is an effective measure to increase spawning rate and hatching rate.
2. The use of spawning beds to mobilize can adjust the height according to need, pick out male individuals in time, reduce the semen in the water body, remove pro-shelled Fish at one time, and prevent water pollution.
3. Under the production conditions, using the egg washing hole and siphon to discharge the upper layer of water can also achieve the effect of washing eggs repeatedly and repeatedly, especially when large areas are used for breeding to avoid egg damage.
4. Feed is an important factor affecting the development of juveniles. Poor feeding or a single feed can cause slow growth of larvae. Individual development is uneven. Due to lack of nutrition, not only the survival rate is low, but also susceptible to disease. All kinds of bait are mixed and fed, and keeping the density of monocytic algae in the water at any time is an effective measure to improve the survival rate of nursery.
5. Loach larvae have higher requirements on water quality, increase the amount of water exchange, and reduce the content of organic matter such as residual baits and feces in the water, which can promote the growth and development of larvae and increase the survival rate.
Author: Dandong Fisheries Technology Extension Station, Liaoning
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