In recent years, the area from south to north of Penaeus Vannamei in China's coastal areas has been increasing year by year, and has been extended to some inland freshwater areas for aquaculture, and has achieved good economic benefits. With the continuous expansion of the aquaculture area, the supply of seedlings directly affects the development of this aquaculture species. Especially in the northern regions, the majority of South American shrimp species are from Guangdong, Fujian, and Hainan due to geographical differences. Affected by many factors such as prolonged transportation, the survival rate of culture is reduced. In order to solve this problem, farmers in the northern region urgently need local production of Penaeus vannamei seedlings. In order to solve this problem, we conducted an exploration of the artificial breeding and desalination technology of Penaeus vannamei, and achieved good results. In this paper, through the summarization of each technical link and technical point in actual production, the method of raising seedlings of P. vannamei and increasing the survival rate of larvae was discussed.
First, the source of nauplii and stocking density At present, most breeding nurseries in the northern region are buying larvae to raise seedlings. When buying, special attention should be paid to the source of broodstock for juvenile field farms. Good nauplii are generally physically strong, not With any germs, the survival rate of young seedlings is relatively high, and the larvae sold during the growing season rarely occur; in addition, transportation time should also be taken into account, and purchases nearby can shorten the transport time. Stocking density is generally controlled at 200,000/m3 to 300,000/m3.
Second, temperature control Although the temperature during the breeding period of P. vannamei is very high, but it is better to change the temperature of seedlings. Nasal juveniles generally have a water temperature of 26°C to 27°C in the south, and ice cubes are added to the packing box. Therefore, when the larvae are transported to the farms after long-distance transport, they should enter the pool at a low temperature (25°C～26°C). After one day of stabilization, the temperature can be raised, and generally there is a braided phase at this time. This method of operation relieves the adverse effects of the temperature difference during transportation and enables the larvae with weaker physiology to recover slowly and robustly; if the larvae are directly put into the pool with water temperature above 28°C, the weaker larvae will Within a few hours of death, the survival rate of nursery was reduced. The suitable water temperature for the development of various larvae is shown in the following table:
puberty
N
Z1 to Z3
M1～M3
P1～P10
temperature
25°C～27°C
27°C～28°C
28°C～29°C
29°C～23°C
When the larvae develop into larvae, body length up to 0.5cm, if desalination is required, the temperature can be lowered and the salt can be reduced at this time. If desalination is not required, cooling should be started. The cooling rate is generally no more than 1°C per day. The pool temperature is basically the same as the outdoor water temperature.
Third, the type of feedstuffs and feeding methods for feeding artificially reared Penaeus vannamei to feeds are basically similar to those of Chinese Penaeus chinensis. In the northern regions, fresh live bait is still the main ingredient. When the supply of fresh live bait is insufficient, substitute bait and shrimp can be used. Feeding fresh live bait not only reduces the cost of raising seedlings, but also is an important part of raising the survival rate of nursery. Specifically feed the following table:
Developmental feeding species
Z1～Z2
The monocytic algae is the main species, supplemented by rotifers and yeast;
Z2 to Z3
The rotifers are mainly supplemented with unicellular algae and yeast;
M1~M2
The rotifers are mainly supplemented with shrimp slices and marinated eggs;
M2 to M3
Halogen-based, supplemented with rotifers, Cladocera;
P1～P10
Cladocera mainly, supplemented with halogen young, halogen adult feeding frequency: take a small number of methods, and depending on the density of biological feed in the pool to adjust. Common rotifers and cladocerans are fed once every 2 hours, and other types are fed once every 4 hours to 6 hours. Several kinds of bait should be fed alternately. Fresh live bait treatment method: live rotifers, halogen young, soaked in potassium permanganate solution 20mg/L ~ 25mg/L concentration for 5 minutes to 10 minutes, then rinse with fresh water can be fed; fresh round Insects, Cladocera, Artemia adults are filtered with mesh bags of the corresponding mesh size to remove impurities and sewage, washed with clean water and placed in a container. Add 1% to 2% of antibiotics by weight and soak for more than half an hour. Hey.
IV. Water treatment and water exchange In the nursery where the water quality is higher than that in the sea area, there is no hatchling and before Z3～M, the water body shall be disinfected no matter whether it is water supply or water exchange. The larval rearing stage shall start to recharge water in the Z2 period. Or change the water, change the amount of water in each period are as follows: Z2 period of 10% to 20%, Z3 ~ M1 period of 20% ~ 30%, M1 ~ M3 period of 30% ~ 40%, P period of more than 50%.
V. Disease Prevention and Control The common diseases during the nursery period are mainly bacteria, fungi and polyposis, and these diseases should be prevented. Before the nauplii enters the pool, 1ppm to 2ppm of compound sulfamethoxazole is applied to the pool, and then 1ppm to 2ppm oxytetracycline or compound sulfamethoxazole is applied according to the amount of water exchanged for each change of water; Should prevent the invasion of its pathogens, especially when feeding fresh live food should be strictly disinfected, once the disease can be spilled into the pool of 20ppm ~ 25ppm formaldehyde solution and heating 1 °C, 24 hours after the change of water.
6. Desalination of prawn Although P. vannamei is a broad-salted prawn, it is very sensitive to changes in the salinity gradient. Through repeated observations, the prawn can tolerate more than 20‰ salinity. The range of variation is up to 6‰ to 7‰; the range of salinity gradient that can be tolerated in the range of 10‰ to 20‰ is 4‰ to 5‰; the range of gradient tolerable below 10‰ is less than 3‰; especially in the seedling salinity. When the temperature is less than 5 ,, the salinity change that can be tolerated is 1 ‰ to 2 ‰. Therefore, the dilute treatment of prawn must not be rushed. The specific operations are as follows: According to the requirements of farmers, daily desalination 1 to 2 times, each time in the 20 or more hours of desalination 2 to 3, in the range of 10 to 20, each desalination 1 to 2; It is advisable to dilute no more than 1 inch for every 10 feet or less. By diluting this gradient, the survival rate of juvenile shrimp can reach more than 95%, and the survival rate of cultivated can be greatly improved.
First, the source of nauplii and stocking density At present, most breeding nurseries in the northern region are buying larvae to raise seedlings. When buying, special attention should be paid to the source of broodstock for juvenile field farms. Good nauplii are generally physically strong, not With any germs, the survival rate of young seedlings is relatively high, and the larvae sold during the growing season rarely occur; in addition, transportation time should also be taken into account, and purchases nearby can shorten the transport time. Stocking density is generally controlled at 200,000/m3 to 300,000/m3.
Second, temperature control Although the temperature during the breeding period of P. vannamei is very high, but it is better to change the temperature of seedlings. Nasal juveniles generally have a water temperature of 26°C to 27°C in the south, and ice cubes are added to the packing box. Therefore, when the larvae are transported to the farms after long-distance transport, they should enter the pool at a low temperature (25°C～26°C). After one day of stabilization, the temperature can be raised, and generally there is a braided phase at this time. This method of operation relieves the adverse effects of the temperature difference during transportation and enables the larvae with weaker physiology to recover slowly and robustly; if the larvae are directly put into the pool with water temperature above 28°C, the weaker larvae will Within a few hours of death, the survival rate of nursery was reduced. The suitable water temperature for the development of various larvae is shown in the following table:
puberty
N
Z1 to Z3
M1～M3
P1～P10
temperature
25°C～27°C
27°C～28°C
28°C～29°C
29°C～23°C
When the larvae develop into larvae, body length up to 0.5cm, if desalination is required, the temperature can be lowered and the salt can be reduced at this time. If desalination is not required, cooling should be started. The cooling rate is generally no more than 1°C per day. The pool temperature is basically the same as the outdoor water temperature.
Third, the type of feedstuffs and feeding methods for feeding artificially reared Penaeus vannamei to feeds are basically similar to those of Chinese Penaeus chinensis. In the northern regions, fresh live bait is still the main ingredient. When the supply of fresh live bait is insufficient, substitute bait and shrimp can be used. Feeding fresh live bait not only reduces the cost of raising seedlings, but also is an important part of raising the survival rate of nursery. Specifically feed the following table:
Developmental feeding species
Z1～Z2
The monocytic algae is the main species, supplemented by rotifers and yeast;
Z2 to Z3
The rotifers are mainly supplemented with unicellular algae and yeast;
M1~M2
The rotifers are mainly supplemented with shrimp slices and marinated eggs;
M2 to M3
Halogen-based, supplemented with rotifers, Cladocera;
P1～P10
Cladocera mainly, supplemented with halogen young, halogen adult feeding frequency: take a small number of methods, and depending on the density of biological feed in the pool to adjust. Common rotifers and cladocerans are fed once every 2 hours, and other types are fed once every 4 hours to 6 hours. Several kinds of bait should be fed alternately. Fresh live bait treatment method: live rotifers, halogen young, soaked in potassium permanganate solution 20mg/L ~ 25mg/L concentration for 5 minutes to 10 minutes, then rinse with fresh water can be fed; fresh round Insects, Cladocera, Artemia adults are filtered with mesh bags of the corresponding mesh size to remove impurities and sewage, washed with clean water and placed in a container. Add 1% to 2% of antibiotics by weight and soak for more than half an hour. Hey.
IV. Water treatment and water exchange In the nursery where the water quality is higher than that in the sea area, there is no hatchling and before Z3～M, the water body shall be disinfected no matter whether it is water supply or water exchange. The larval rearing stage shall start to recharge water in the Z2 period. Or change the water, change the amount of water in each period are as follows: Z2 period of 10% to 20%, Z3 ~ M1 period of 20% ~ 30%, M1 ~ M3 period of 30% ~ 40%, P period of more than 50%.
V. Disease Prevention and Control The common diseases during the nursery period are mainly bacteria, fungi and polyposis, and these diseases should be prevented. Before the nauplii enters the pool, 1ppm to 2ppm of compound sulfamethoxazole is applied to the pool, and then 1ppm to 2ppm oxytetracycline or compound sulfamethoxazole is applied according to the amount of water exchanged for each change of water; Should prevent the invasion of its pathogens, especially when feeding fresh live food should be strictly disinfected, once the disease can be spilled into the pool of 20ppm ~ 25ppm formaldehyde solution and heating 1 °C, 24 hours after the change of water.
6. Desalination of prawn Although P. vannamei is a broad-salted prawn, it is very sensitive to changes in the salinity gradient. Through repeated observations, the prawn can tolerate more than 20‰ salinity. The range of variation is up to 6‰ to 7‰; the range of salinity gradient that can be tolerated in the range of 10‰ to 20‰ is 4‰ to 5‰; the range of gradient tolerable below 10‰ is less than 3‰; especially in the seedling salinity. When the temperature is less than 5 ,, the salinity change that can be tolerated is 1 ‰ to 2 ‰. Therefore, the dilute treatment of prawn must not be rushed. The specific operations are as follows: According to the requirements of farmers, daily desalination 1 to 2 times, each time in the 20 or more hours of desalination 2 to 3, in the range of 10 to 20, each desalination 1 to 2; It is advisable to dilute no more than 1 inch for every 10 feet or less. By diluting this gradient, the survival rate of juvenile shrimp can reach more than 95%, and the survival rate of cultivated can be greatly improved.
Heng Li Seafood Co., Ltd. , http://www.zz-food.com