CATDOLL : CATDOLL: When does the wood frog start laying eggs?

1. When does the forest frog start laying eggs?

The forest frog lays eggs in early spring (starting after Qingming Festival), and the egg mass can develop normally at low temperatures (above 6℃). At present, most frog farmers use outdoor hatching ponds, and put 2 to 3 egg masses per square meter of water surface for direct hatching, with a hatching rate of about 40% to 60%. The hatching rate is not only related to the construction standards of the hatching pond, artificial hatching technology and management level, but also restricted by natural conditions in the field. For example, the wind will cause the eggs to gather together, resulting in late development of the lower eggs and uneven embryo development; the low temperature will affect the slow development of the embryos, and the occasional freezing damage will cause the embryos on the surface of the egg mass to freeze to death; it is inconvenient to manage and is often attacked by natural enemies. In order to improve the hatching rate of artificially raised frogs, according to the basic conditions that should be met for the hatching of forest frog egg masses, a small bow shed (Figure 5-1) is used to hatch forest frog eggs, and the objective conditions for the hatching of forest frog egg masses are artificially improved, which can improve and ensure the hatching rate of forest frog egg masses.

2. What is the egg-laying process of the Chinese forest frog?

The spawning period of Chinese forest frogs varies according to the climate conditions in different places. In Liaoning Province, it starts from early April and lasts until about mid-April; the spawning period of Jilin forest frogs starts from late April and ends in early May. Forest frogs can lay eggs when the water temperature is above 5 degrees, and the most suitable temperature is 8 degrees to ire. Within a day, forest frogs also have a certain pattern of spawning. They lay more eggs in the early morning, less eggs in the afternoon and night, and stop laying eggs in the second half of the night. The ovulation time of forest frogs is relatively short, usually 3 to 5 minutes. All the eggs in the uterus on both sides are discharged at the same time. Each female frog only lays one egg mass, and each egg mass of two-year-old frogs contains about 1,000 eggs, and each egg mass of three-year-old frogs contains 1,500 to 2,000 eggs. The egg mass is spherical or elliptical, and the egg mass is covered with an egg membrane. The egg membrane can protect the eggs from external mechanical damage; some people also believe that the egg membrane is related to the fertilization ability of the eggs, and eggs that lose the egg membrane are mostly unfertilized eggs. After the eggs are laid, the egg membrane absorbs water and expands, floating on the water surface. The wood frog is also selective about the spawning site, and likes to lay eggs in small water surfaces, still water, and shallow water areas, preferably with a water depth of 15 to 20 cm.

3. What are the characteristics of the spawning area of ​​the forest frog?

The spawning grounds of wood frogs can be divided into two parts: spawning area and non-spawning area. The spawning area is generally located in the shallow water at the edge of the spawning ground, with a water depth of about 5-10 cm and a maximum depth of no more than 25 cm. Wood frogs usually lay eggs in the shallow spawning area. The non-spawning area refers to the deep water part of the spawning ground, with a water depth of less than 1 meter and more than 25 cm. After the egg mass absorbs water and expands, it floats on the water surface, covering the surface of the spawning ground and also distributed on the surface of the deep water area.

4. What are the characteristics of the eggs laid by female forest frogs?

The female wood frog lays only one egg mass at a time, and lays eggs once a year. The number of eggs laid varies significantly with age. The average number of eggs laid by a two-year-old wood frog is 1,300, the average number of eggs laid by a three-year-old wood frog is 1,800, and the average number of eggs laid by a four-year-old or older wood frog is 2,300.

5. How to artificially control the spawning of forest frogs?

Farmers should especially remember:

(1) The minimum temperature for Rana sylvatica to lay eggs is 2°C, and the most suitable temperature is 10°C.

(2) Like fish, wood frogs are animals that undergo external fertilization. The wood frogs mate by "embracing each other", that is, the male frog lies on the back of the female frog, and uses his forelimbs to tightly embrace the female frog's chest and abdomen from under her ribs. At the same time as the female frog lays eggs, the male frog begins to ejaculate.

Then the frog sperm and frog eggs begin to combine outside the body. The tighter the male frog holds, the more excited the female frog becomes, and the faster she ovulates.

(3) The female frog's ovulation time starts at midnight every day. The peak of egg-laying is at 5 a.m. The male and female frogs can "hold their foetus" for 4 to 6 hours.

(4) The ratio of male frogs to female frogs is 1:1. However, practice has shown that if you want to make the forest frogs ovulate quickly, you can release 20% more male frogs. This will cause competition and stimulate the speed of ovulation.

(5) Release the frogs in a 1:1 ratio into a 1.3-meter-high plastic-enclosed spawning pond. The standard for release is 50 pairs per square meter. If you want to speed up spawning, release 20% more male frogs.

By remembering the above principles, you can create the most suitable temperature conditions, release frog species in a timely and scientific manner, shorten the egg-laying period, and enter the incubation period ahead of time.