Release technology of silverfish in reservoir

As far as possible, the choice of release site is in the reservoir bay with a certain distance from the shore, a water depth of about 2 meters, and rich in small-scale bait organisms such as hard sediment or gravel bottom and insects, and several delivery sites should be selected at the same time to avoid failure caused by improper delivery of one point.

Fish egg delivery method when the fertilized eggs are transported to the destination, the nylon bag containing the fertilized eggs is first put into the water. When the water temperature in the bag is basically the same as the water temperature in the reservoir (the temperature difference is less than 3 ℃), the fertilized eggs are dispersed into the water slowly and evenly, and each injection point should have a certain range. The northern region should hit more ice holes and throw the fish eggs directly into the water from the ice eyes. The action of laying eggs should be quick to avoid freezing the fish eggs. If the bottom is thick, open several ice holes 1 meter square on the ice surface, first sink the cage under the water surface, then drop the fertilized egg, slowly sink the cage to a depth of 2 meters, and secure it with a plastic float.

The management of ice-free reservoirs after the release of fertilized eggs shall be protected for one month after the release of fish eggs, mainly by prohibiting water and underwater activities such as net-pulling and fishing in this area. Frozen reservoirs, especially those where fish eggs are dropped in cages, should be inspected frequently in the first few days to prevent the cages from being raised to the surface and causing damage to the fish eggs. Half a month later, break the ice to lift the cage to the surface and brush off the attachments on the cage with a brush. At the same time, it can suck out certain eggs, check the embryonic development and survival rate, and then slowly sink the cage into the water. The hatching time of fish eggs in the low temperature environment of 1.5 ℃ ~ 5 ℃ was 63 ~ 65 days, and the water temperature was 6 ℃ ~ 7 ℃ when they came out of the film. When the water temperature during the incubation period is 2 ℃ ~ 10 ℃, the incubation time is 30 days. The days of coming out of the film at 11 ℃ ~ 16.5 ℃ water temperature are about 6 days.

Transfer density and repeated transfer of large and medium-sized reservoirs (lakes) generally transfer 150-800 fertilized eggs per mu. Usually after a transplant, it should be repeated in the second year to expand the population and enhance the viability of the population. In addition, according to the biological characteristics and living habits of silverfish, adult transplantation can also be carried out in the low temperature period (difficult). The time is usually from November to December, the water temperature is 10 ℃ ~ 15 ℃, and the male-to-female ratio is 3:1. The transportation can be carried out with 50 fish in each bag, and the whole process can not be touched by hand.