(i) Broodstock, egg harvesting and transportation Every year from May to June, fishers swim up to the spawning group along the coast for broodstock. Adult fish weighing 1.5-4 kg range, male to female ratio of 1:9; weight ratio of 3-7 kg male to female ratio of 1:3. Regardless of the type of broodstock that is caught by the fishery method, it is best to perform artificial insemination within two hours after catching, so that a higher fertilization rate can be obtained. The red fin eastern porpoise is a one-time spawning type fish. The spawning water temperature is about 17°C, and the spawning season is concentrated. The abortion period is very short. Puffer eggs produce sticky eggs and have stickiness. It is advisable to pick eggs in plastic buckets that are not easily attached. First add 5-10L of clarified seawater to the barrel and squeeze the fish into the water. Then add 1 to 2 tails of male semen to make the seawater look milky and bloody. After stirring, let it stand for 5-10 minutes and wash eggs continuously with clean water. 3 - 5 times until the seawater is completely clarified. Within a few hours, fertilized eggs can be transported in short distances. A plastic bag with a capacity of 20L can contain 10L of seawater and 1.5 million eggs, and it can be filled with 5L pure oxygen and sealed and then transported in a packing box. For long-distance transportation between 7 and 10 hours, 5L of seawater and 50,000 eggs were filled into the plastic bag, and then 5010-6 streptomycin sulfate was added to prevent bacterial growth. Zhakou packing and waiting for shipment. If it takes several days to transport, you need to inflate the bag and change the water one or two times a day. If you do not have aeration, you can increase the number of water changes.
(B) Incubation of the red-finned Oriental dolphins has an egg diameter of 1.2-1.4mm. The newly fertilized eggs are soft and harden after several hours. After a few days, the volume and weight of fertilized eggs are reduced by about 12-15% compared with the first fertilization. The fertilized eggs are calculated at 600-700 grains per gram. Due to the opacity of the egg membrane, it is not easy to observe its development. However, after 4-5 days, the fertilized eggs turn yellow or purple, and live fertilized eggs are milky white and shiny. Pigment cells appear before and after eyelid development and are easily recognizable through the egg membrane. Using a transparent polyvinyl chloride incubator with a diameter of 10cm, a height of 100cm, a volume of 180L, a funnel-shaped bottom, and an egg arrester in the middle. Inflate from the bottom to keep the eggs spinning. The inflow from the incubator and the elbow drain from the bottom maintain the free circulation and the maximum daily water change is 8 times. The incubator should be placed in a room with an illumination of about 500LX. Each incubator can contain 50-100 million fertilized eggs, and it is generally preferable to put in 20-30 million grains. The incubation time varies depending on the water temperature. It takes about 15 days at 13-15°C and about 10 days at 15-17°C. It usually takes 3-4 days from the start of hatching to the end of the hatching. Little hatching occurs on the first day and hatching takes place on the second day. Out of 70%, incubate 20-30% in the third and fourth days. When the larvae separate from the hatchery, the air-inflation is stopped first, the egg is submerged at the bottom, and the larvae float to the upper-middle layer, then all the newly hatched larvae can be scooped out with a scoop, and then the dead eggs that have a small proportion of seawater are gently collected in the center of the surface layer. Remove it.
(C) embryo and larvae development characteristics of puffer fish fertilized egg opacity, it is difficult to observe the continuous development of embryonic development, as described below only its development characteristics at 18 °C -20 °C water temperature conditions. 15h after fertilization is a multicell stage, 24h after fertilization is a high blastocyst stage, 30h after fertilization is a low blastocyst period, 42h after fertilization is the original intestine stage, 3 days after fertilization embryo formation, 4 days after fertilization as the eye period, Embryos were 1/2 around egg yolk and larvae hatched 6 days after fertilization. The newly hatched larvae have a full length of 2.4-2.6mm. The yolk sac is large. There are a large number of yellow pigment cells on the surface of the oil globules. The eyes are large, the mouth concave is small, the body is round and thick, and the pectoral fins are formed. The larvae on the third day after hatching were 2.7-3.2mm in length, with an average of 3.0mm. The mouth was opened and the diameter of the mouth was about 300mm. Underdeveloped jaws, yolk sac remaining 1/2. The larvae on the 5th day after hatching were 3.2mm-3.8mm in length and 3.4um in average. The yolk sac disappeared and a few survived. Has begun to eat rotifers and shellfish larvae. The larvae on the 10th day after hatching are about 5mm in length. The pectoral fins are more developed and the anal fins have differentiated. At this point larvae began to appear "drum" habits, from the performance of inhalation after the water or encountered the enemy, the abdomen expanded like a ball, began to feed Artemia larvae. After larvae on the 16th day after hatching, the larvae were about 6.5mm in length and nearly 8mm in size. When they entered the juvenile stage, the dorsal, caudal, and anal fins began to differentiate and form teeth, and a large number of small prickles appeared in front of the abdomen. At this time, the swimming speed is fast and the cluster is obvious, mainly feeding Artemia larvae. The larvae on the 25th day after hatching have a total length of 18-20mm. The fins are well-developed, yellowish, and greenish on their backs. Each side of the left and right pectoral fins has a white circle-shaped “big round spotâ€. The upper and lower jaws form two well-developed incisors. Become young fish. Feed on Artemia adults, shrimp or fish gills.
(4) The fry cultivation can be carried out in a large cement pool or a small glass steel tank in the early stage of cultivation, and it can be cultivated to 5-6mm, which generally takes 10-15 days.
(1) Cultivation conditions. Use 20-60m3 cement tank or 1-2m3 fiberglass tank. The inner wall of the container is based on the dark color. The illuminance is controlled at 500-1000LX. The water temperature is 15-20°C, PH7.8-8.2, salinity 28- 30%, dissolved oxygen is not less than 4mg/l, can be micro-inflated, the culture density of 20,000 / m3-30 000 / m3 early hatch larvae is appropriate.
(2) Feeding of bait. The newly hatched larvae were open the next day, the mouth cracked about 300um, can be directly fed rotifers as an open bait, rotifer feeding density of 10-20 / ml, feeding 3-6 times a day. When larvae are close to 5mm in length, they can be supplemented with Artemia larvae or copepods.
(3) Daily management. In the early stage, hydrostatic cultivation can be adopted, changing the water 2-3 times per day, changing the water volume every time by 1/3-1/2, and changing the water before feeding. Clear bottom 1-2 times daily. The light transmittance of the workshop should be set up shading screen adjustment. Pay attention to the observation of water quality and food intake, observation of growth, and finding problems in time to take measures.
(4) Out of the pool. When the larvae are full-length to 5-6mm, there will be differences among individuals, mutual disability phenomenon, and at the same time the density will influence the cultivation. Rapidly lower the water level when leaving the pond, remove the eel fry count, and move it to the rear cultivation tank. The pre-cultivation survival rate is generally around 50-60%.
Post-cultivation (1) Cultivation conditions. 20-60m3 cement pool is generally used. The water depth is about 1m. The illuminance increases with the growth of the fry. It can be directly cultivated in the outdoor open-air pool. When the indoor cultivation, the light transmittance can be increased to facilitate the increase of the water temperature and accelerate the growth of the fry. The water temperature should be increased to 20-28°C. The culture density should not be too high, with 1500-2000 tails/m3 being appropriate.
(2) Feeding of bait. Artemia larvae or copepods are mainly Artemia larvae feeding amount is 0.1-1/mL, feeding 4-6 times a day, increasing the amount of feeding and times as the fry grows, and starting when 9-10mm. Feed chilled baits such as prawn and fish oysters until they are out of the pond. In recent years, there have also been examples of using homemade bait to feed fry. In short, no matter what kind of bait is used, it is necessary to ensure adequate quality and supply in order to prevent the increase in residual food.
(3) Growth and ecological characteristics. 5mm larvae body color will change with the intensity of light, and the phenomenon of "drumbling" and mutual attacks, but the residual food is not yet obvious, 7-8mm into the juvenile period, the initial formation of teeth, began to eat each other and As the growth of residual food intensifies, the attacker “drums himself until he is bitten to death. At this time, the mortality rate of fry is increased. The organs of fry above 12 mm are basically well-developed and transferred to middle and lower levels of activities and feeding. The total length is about 18 mm, and metamorphosis is Juvenile fish, basically the same shape as the adult fish, entered the late growth, the growth rate was significantly faster, and slightly faster than the indoor outdoor.The survival rate was 35-50% in this period.
(4) Daily management. Change water or water culture can be. Start changing the water 0.5-1 times, 8mm when the amount of water to increase to 2 times, after feeding chilled bait, the water quality is easily contaminated, the flow of water should be cultivated and exchanged 2-4 times a day. Medium air volume. Feeding baits should gradually increase the amount and frequency, especially in the early morning to feed. Into the juvenile period can be sorted according to different specifications. We must strengthen water quality testing and disease prevention in peacetime.
(5) Out of the pool. Usually the size of the pool is 20-30mm. At this point the fry has finished eating into the juvenile period. The adaptability is strengthened, the cultivation is stable, and it can be discharged in time for breeding and breeding.
(6) Transportation. At present, the main tools for seedling transport are live water boats, oxygenated bags, canvas buckets and other species. In recent years, China has begun to use closed live fish transport vehicles and oxygen-filled bags for air transport fry which have been widely used in long-distance transportation.