Hatching technique of Shrimp in bumper year

Harvest shrimp, also known as harvest worms, fairy shrimp, etc., are widely distributed in salt fields or salt lakes on land, and are widely used in aquaculture. Reproductive methods can be divided into egg laying and egg viviparity. Eggs will be induced to form durable eggs in poor environments such as high salinity and low dissolved oxygen, and fertilized eggs will directly develop into nauplius larvae under low salinity and high dissolved oxygen. Let's take a look at the hatching techniques of bumper shrimp.

Mode of reproduction

There are two forms of reproduction in harvest shrimp: unisexual reproduction and bisexual reproduction (parthenogenesis), both of which can lay nauplii or ovulate directly. In the case of direct ovulation, the eggs laid are divided into summer eggs and winter eggs. After the summer eggs are laid, they quickly hatch into nauplii in the water, which is basically the same as the nauplii laid directly by the mother. On the other hand, the winter eggs are dormant eggs, which will only be laid when the living environment of the shrimp changes greatly in the harvest years, such as cooling, rising proportion of sea water, lack of food, chemical stimulation and so on. Dormant eggs have thick shells, can tolerate adverse environmental conditions, and generally do not hatch directly in the water. They all need to return to the water after a certain period of diapause before they can hatch. Most of the resting eggs are buoyant.

Incubation condition

1. Salinity: between 10/1000 and 15 10~15ppt is the best, that is, there are 10 to 15 grams of salt per liter of water, which translates to a specific gravity of about 1.01 to 1.02 (natural sea water contains 30 to 35 grams of salt per liter, or 30~35ppt, with a specific gravity of 1.022 to 1.026).

2. Temperature: the water temperature should be between 25 and 30 ℃, and the higher temperature helps to shorten the incubation time.

3. PH: pH should be between 7.5 and 8.5.

4. Dissolved oxygen: it is generally necessary to pump air to make the water boil to provide enough dissolved oxygen (nearly saturated). The incubation time varies with the species of shrimp in the harvest year and the temperature of the water, usually between 18 and 36 hours.

Shrimp egg selection

1. The color of good harvest shrimp eggs should be brown and shiny, the hands should not feel wet, there should be no mildew and fishy smell, and there is less sediment in the eggs.

2. Crush the eggs with two pieces of glass, count the number of eggs with and without oil drops in the broken eggs, and determine the ratio of good eggs to bad eggs (eggs with oil drops are good eggs). If there are more eggs without oil drops, the reason may be mixed with a large number of egg shells, so you should pay more attention when you buy them.

3. Observe with a magnifying glass and roughly estimate the proportion of round, shrunken and damaged eggs. Most of the sunken eggs are caused by dehydration, if there is no damage, it is a good egg.

4. Samples can be taken for hatching if possible. The hatching rate without eggs and the same number of nauplii hatched are the same, and the shorter the time required, the better the harvest shrimp eggs. The hatching time of such egg larvae is more uniform and easy to collect.

Hatching method

1. Shallow dish hatching method: take a long and shallow shallow dish to inject the previously prepared hatching water, sprinkle the abundant shrimp eggs evenly on the water surface, and hatch into nauplius larvae after 24 hours and 36 hours. when collecting, the nauplius larvae are collected with light at one end of the plate and then collected with an eyedropper. This method is not suitable for mass hatching.

2. Deep-water hatching method: take a deep and wide container (two-liter Baote bottle), fill it with water ready for hatching, pour in an appropriate amount of harvest shrimp eggs, then insert an air hose to boil the water and let the shrimp eggs roll in the water. After 24 hours and 36 hours, the shrimp eggs can hatch into nauplius, which is the most common method.