Practical culture techniques of herring

I. Ecological habits

1. Eating habits

Fish herring is a carnivorous fish, fish fry, fish species stage mainly feed on zooplankton. When the body length is about 15cm, you change your eating habits and begin to eat small screws. With the development of the lower pharyngeal teeth, the crushing function is enhanced, and the young fish feed on molluscs, such as clams, snails and so on. In addition, they also eat shrimp, crabs and insect larvae.

2. Growth

Herring is large and grows rapidly, with a maximum weight of up to 70kg. 1-year-old fish can grow up to 500 g, 2-year-old fish can grow to 2.5 kg,3, and 3-year-old fish can grow up to 6.5 kg in a good environment. The growth rate of body length of black carp was the fastest at 2 years old and slowly after 5 years old, and the body weight increased fastest at 4 years old and continued to gain weight after 5 years old.

3. Reproduction

Herring is a migratory fish. it grows and develops in the affiliated water body of the river. it overwinters into the river in winter, overwinters the parent fish after the beginning of spring, develops rapidly to maturity in the process of tracing, and propagates in the spawning ground of the main stream of the river. after spawning, the parent fish fattened into the accessory water body. The breeding season is from May to June every year, and the water temperature is required to be 18 ℃ 28 min. When the spawning ground rises, the water velocity 1-2m/s, the flow pattern changes, and the parent fish begin to spawn. Herring eggs float and hatch and develop with the flow of water. The age of sexual maturity of herring is 7 years old for female fish and 5 years old for male fish. Type of spawning: the gonads of sexually mature individuals mature once a year and lay eggs once a year. The number of eggs laid by herring increases significantly with the increase of body weight. Generally speaking, the number of eggs laid by 15-20kg parent fish is about 600000-1 million eggs.

2. Artificial propagation

1. Source of parent fish

The natural seedlings in the river basin or the seedlings produced by the national original seed farm, or the adults preferably collected from the natural species resource bank, or from rivers, reservoirs, lakes and other natural waters that have not been artificially released, and then cultivated as parent fish. Inbred offspring cannot be used as a source of parent fish.

2. Parent fish culture

The main results are as follows: (1) the parent fish should be more than 6 years old and weigh more than 15 kg. The ratio of female to male is 1: 1.5, and about 10 herring with 15 kg / mu are released.

(2) the bottom of the parent fish pond is flat, sandy loam is better, and the water quality is fresh, mainly feeding snail, clam and clam meat, supplemented with a small amount of bean cake and malt, adding new water and flushing water regularly, generally flushing once a month in winter and keeping the water depth more than 2 meters. After the beginning of spring, lowering the water level is easy to increase the temperature of the pool water, flushing once a week, increasing the flushing times in the middle of April, flushing once every 2-3 days to promote gonadal maturation.

(3) in the parent fish pond, a small amount of silver carp is used to regulate the water quality, and at the same time, carnivorous fish such as black fish and California perch can be properly raised to prey on the wild miscellaneous fish in the pond, which is beneficial to the cultivation of parent fish and increase the benefit of the pond.

3. Brood fish to induce spawning

(1) the time of induced labor and water temperature: in the middle and lower reaches of the Yangtze River, the time of induced labor is in the middle and late May, and the water temperature of 25: 28 is the most suitable.

(2) selection of parent fish: the maturity of parent fish directly affects the effect of induced spawning. the identification criteria are that the male fish gently squeeze the abdomen and release semen immediately after meeting the water, and the abdomen of the female fish is inflated, soft and elastic, and the abdominal scales are sparse. In order to improve the population maturity, we can check the net in the middle of April. For those with poor maturity, according to the individual size and maturity, according to the individual size and maturity, LRH-A3~5 micrograms / tail will be injected respectively.

(3) injection of oxytocin: commonly used oxytocin is LRH-A, DOM, PG, etc., usually the mixed effect of the two is better, our field uses three-needle injection, the rate of induction is higher, up to more than 95%. The first injection of LRH-A1 micrograms per kg of parent fish, needle distance of 20 hours; the second injection of LRH-A5 micrograms per kilogram of parent fish, needle distance of 8 hours; the third injection of female parent fish per kilogram of LTH-A20 micrograms plus PG3~4 mg or plus DOM4~5 mg, male parent fish dose according to the specific circumstances of the female parent fish dose of 1x3x1x2, the injection was done through thoracic cavity.

4. Estrus and artificial insemination

The length of the effect time varies with the water temperature. It is observed that the effect time is 6-7 hours when the water temperature is 26-28 degrees. When the parent fish are in estrus at a predetermined time and combined with the actual situation of estrus, the parent fish are caught for artificial insemination, and attention should be paid to light and fast action during insemination. When sperm and eggs are mixed, 0.6% normal saline is properly injected to prolong the insemination time. At the same time, direct sunlight and Rain Water splash should be avoided during insemination to improve the fertilization rate, and the normal fertilization rate is more than 90%.