CATDOLL : CATDOLL: How to catch river shrimp in the river? What are the living habits of river shrimp?

How to catch river shrimp in the river? What are the living habits of river shrimp?

1. Catch shrimps with shrimp cages. Shrimp cages are usually made of bamboo strips or bandages, with a diameter of usually 15 to 40 cm. They are "丁"-shaped cylindrical cages. They are low-cost, simple methods, and have good shrimp catching effects.

2. Catching shrimps with shrimp balls. Shrimp balls are also called shrimp cages in some places. They are more effective in catching shrimps in lakes, ponds, weedy rivers and other waters.

3. Catching shrimps with ground traps and swinging cages. Ground traps are also called ground dragon nets. They are in the shape of a square cylinder with a "T" shape. In some places, they are called swinging cages. Most of the swinging cages are square cylinders.

2. Living habits of river shrimp

River shrimp are crustaceans, related to crabs and lobsters. They have a flat, flexible, translucent body in the middle and a fan-like tail. Shrimp are good swimmers, using their legs to travel long distances.

When it swims, its swimming legs frequently and neatly paddle backwards like wooden oars, and its body slowly moves forward. When it is frightened, its abdomen flexes and stretches quickly, and its tail paddles downward and forward, and it can continuously leap backwards at a very fast speed. Some shrimps are not good at swimming, and large lobsters spend most of their time crawling on the sand and rocks on the seabed.

Additional information:

Nutritional value of river shrimp:

1. It has high nutritional value, can enhance the body's immunity and sexual function, nourish the kidney and strengthen yang, resist premature aging, and can treat kidney deficiency, impotence, chills, fatigue, waist and knee pain and other symptoms.

2. It is rich in magnesium, which plays an important regulatory role in heart activity and can protect the cardiovascular system very well. It can reduce the cholesterol content in the blood, prevent arteriosclerosis, and also dilate the coronary arteries.

3. The astaxanthin in shrimp helps eliminate the "jet lag" caused by jet lag.

References Sources:

Baidu Encyclopedia - River Shrimp

Best fishing in summer

(a) Shrimp cages are usually made of bamboo strips or bandages, with a diameter of 15-40 cm and a "丁" shape.

The cage has two entrances through which shrimps can enter but not easily exit, and an opening at the junction of the "丁"-shaped cage.

The opening is equipped with a lid. Before operation, fish bones, rice bran, wheat bran and other baits are placed here and covered. Hundreds of them are tied together with ropes.

The cages are tied together at intervals of 4-10 meters. Some shrimp cages are placed separately, and small bamboo poles are tied to the shrimp cages.

Or tie a small rope with a buoy at the other end and place it in the water. Put the cage in the evening and collect it the next morning. Open the lid and take out the shrimp.

Locals use small, cylindrical plastic shrimp cages with only an inlet at one end and a lid at the other end, which is low cost and

The method is simple and the fishing effect is good.

(ii) Shrimp Ball Catch Shrimp balls are also called shrimp cages in some places. They are caught in lakes, ponds, and weedy rivers.

The shrimp ball is made of bamboo strips, willow branches, and bandages, with a diameter of 60-80 cm and is an oblate hollow

To make a ball, you can fill the empty ball with broken nets, bamboo shoots, bamboo threads, palm fibers, etc., and tie it with a rope.

When working in shallow water, shrimp balls are sometimes directly tied with a small bamboo pole as a mark and put into the water.

The shrimps will live and feed inside the shrimp balls. Usually, every 30-120 minutes, a small boat will be rowed to the surface of the water where the shrimp balls are placed.

Use one hand to operate the row hook, hook the shrimp ball firmly and gently lift the shrimp ball to the surface of the water, or grab the buoy or bamboo pole and gently lift the shrimp ball to the surface.

Use your other hand to place an elliptical or trapezoidal scoop net with an area of ​​0.3-0.8 square meters 30-50 cm underwater.

Then pull the shrimp balls into the scoop net, and then transfer the shrimps in the scoop net to the boat cabin or fish basket for temporary storage.

If you are using a net, you can directly lift the shrimp balls into the boat and shake the shrimps out of the balls into the boat. This method is simple, but some shrimps may

If you put some small fish or flour balls in the shrimp balls as bait, the fishing effect will be better.

(III) Ground Cage and Sling Cage Ground Cage is also called Ground Dragon Net, which is square cylinder or T-shaped. In some places, it is called Sling Cage.

Most of the cages are square cylinders. They are mostly made of PE wire, with an inner diameter of 40-60 cm, a length of 3-10 meters, and pointed ends.

It is composed of multiple sections, usually 7-16 sections, each section is supported by a circle made of iron wire or bamboo strips, and each section is made of mesh.

The inverted barbel has a diameter of 10-20 cm, and the last section is a net bag to hold the catch.

In waters with aquatic plants and slight currents, place ground traps and swing cages in shallow water areas of lakes, reservoirs, ponds and rivers.

Once in the evening, take out the shrimp from the net bag. If bait is put in the ground cage, the fishing effect will be better.

(IV) Shrimp and oyster fishing Shrimp and oyster fishing is done by using a trumpet-shaped bamboo cage made of bamboo strips, which is long and thin and has a large entrance.

The river shrimp likes to live on water plants during the day and go out at night to swim upstream.

The habit of the river, ditch, stream, choose the bank with water flow, use weeds to build dams (the size of the dam should be such that the water flow

The water level is increased due to the obstruction and flows through the dam, forming a backflow. Shrimp and oysters are placed in the backflow to catch river shrimp.

What are the living habits of green shrimp?

The scientific name of the green shrimp is Macrobrachium, which is mainly distributed in freshwater waters of China and Japan. It has the advantages of high reproductive capacity, strong adaptability, wide diet, delicious meat, and can be marketed all year round. Its living habits have the following characteristics:

1. Macrobrachium is an omnivorous aquatic animal that prefers animal feed. Artificial breeding mainly relies on commercial feed.

The most suitable water temperature for its growth is 18-30℃. When the water temperature drops to 4℃, it enters the wintering period. When the water temperature rises above 10℃, its vitality increases and its feeding gradually increases.

2. They live on the bottom and prefer to live in slow-flowing places with dense aquatic plants. The depth of their habitat varies from 1-2 meters to 6-7 meters. In summer and autumn, they forage and reproduce in shallow water near the shore. In winter, they move to deeper water areas to hibernate and rarely eat or move.

3. When the water temperature is around 18℃, sexually mature shrimps begin to mate and lay eggs. The mating of shrimps usually takes place when they are close to spawning.

4. Shrimp are backlit, hiding in the dark during the day and coming out at night. However, during the reproductive season, they will come out during the day to mate and also come out to compete for food during the day when feeding.

Shrimp is an omnivorous animal. Juvenile shrimp feed on plankton. Adult shrimp in natural waters mainly feed on various benthic small invertebrates, carcasses of aquatic animals, sessile algae, various filamentous algae, organic debris, plant debris, etc. Artificially cultivated shrimp can eat a variety of commercial feeds, such as distiller's grains, tofu dregs, bean cakes, silkworm pupae, clam meat, wheat flour, fish meal, rice, snails, and especially like to eat maggots.

Shrimp mainly rely on their sense of smell or tentacles to find food. When foraging, the tentacles of the shrimp constantly explore in the water. When they find food, they use the first and seventh pairs of legs to clamp the food and send it to their mouths. The digestive tract of shrimp is straight and short, so they often need to eat constantly. When they are extremely hungry, they will even cannibalize each other.

Green shrimps usually like to live in quiet corners, hide in caves, or live among water plants. They have territorial behavior in the competition for food, space and mates, and will not allow other shrimps to invade. Once they find an invader, they will raise their second pair of legs to drive it away.

Green shrimps usually live in aquatic plants, so an appropriate amount of aquatic plants must be planted or artificial shrimp nests must be set up in the shrimp pond. Generally, local materials can be used, such as ready-made tree roots or plastic nets.

It lurks in the dark during the day and comes out at night, so it is best to feed the shrimp in the evening. It only comes out during the day when looking for a mate.

Green shrimps like to swim upstream. When encountering an enemy, they will first use their second pair of legs to defend themselves. When in danger, they will retreat quickly to avoid the enemy by flexing and extending their abdomen and paddling the water with their tail fans.

Green shrimps have poor swimming ability and can only swim short distances, often climbing and crawling in the grass at the bottom of the water. However, when frightened or attacked by enemies, they can use their abdomens to contract sharply, their tail fans to paddle the water backwards, and then suddenly straighten their bodies and escape from the water.

Green shrimps are euryhaline and can live in freshwater and low-salinity estuary waters. They often cluster in coastal waters with dense aquatic plants and slow currents. They usually feed and move in shallow coastal waters in summer and autumn, and move to deeper waters in winter and spring to hibernate. They have a wide range of suitable temperatures and can spend the winter naturally.

Green shrimps have weak swimming ability and can only swim short distances. They spend most of their time clinging to water plants or other aquatic objects. When encountering enemies, they rely on the sudden contraction of their abdominal muscles to bounce backwards.

The feeding intensity of freshwater shrimp mainly depends on the water temperature. Generally, they start feeding in March when the water temperature rises to about 14℃. The feeding intensity is highest from April to October. They enter the hibernation stage during the low temperature period in December and rarely feed. They only eat a small amount when the temperature rises slightly.

Green shrimp is a major economic shrimp widely distributed in freshwater areas. It is rich in nutrition, tender and delicious, and is a precious aquatic product that is deeply loved by people. It lives widely in freshwater lakes, rivers, ponds, and swamps. The green shrimp produced in Baiyangdian, Hebei Province, Taihu Lake, Jiangsu, Siyang County, Xinghua City, and Weishan Lake, Shandong are the most famous.

Green shrimps like to live in shallow waters along rivers, lakes, ponds, ditches, or slow-flowing waters with dense aquatic plants. They stay dormant in the dark during the day and are active at night, often crawling on the bottom of the water, aquatic plants, and other objects. ⒈ Water quality

The water should be fresh, have high hardness, be rich in dissolved oxygen, be alkaline, and meet the fishery water quality standards.

2. Water temperature

The water temperature should not be too high or too low. The most suitable water temperature is 20-25 degrees, and the peak breeding period is 26-30 degrees.

3. Dissolved oxygen

Green shrimps cannot tolerate low-oxygen environments. Their oxygen consumption rate and suffocation point are higher than those of ordinary fish. When the fish pond is lacking in oxygen, green shrimps will be the first to float to the surface and die.

4. Light

Light is an important factor in the growth and fattening of freshwater shrimp. Adult shrimps are more afraid of light, but young shrimps have a strong phototaxis. Freshwater shrimps are selective about light colors. Yellow and green light are more likely to cause phototaxis, while red light has a photophobia reaction. Freshwater shrimps grow fast. The young plants hatched in May and June can generally grow to about 3 cm in about 40 days, and each can generally weigh 3-5 grams in November. Freshwater shrimps shed their skin 13-15 times in their lifetime. Their growth and development are completed by molting, and their life span is generally 14-18 months.

The breeding season of green shrimp is from April to August every year, with the peak period from June to July. The breeding water temperature is 18℃~29℃, and the optimum temperature is 22℃~27℃. The shrimp can reach sexual maturity and lay eggs in the same year. Generally, each parent shrimp can lay eggs 2~3 times in each breeding season. Spawning activities are mostly carried out at night, and eggs are laid 24 hours after mating. The amount of eggs laid is related to the size of the body. The amount of eggs laid by 4~6 cm parent shrimp is 600~5000, and generally 1000~2500. The eggs are attached to the abdominal limbs for hatching, and it usually takes about 20~25 days to hatch into flea-like larvae.

There are several methods for artificially breeding freshwater shrimp, including cage breeding, pond breeding and mixed breeding of fish and shrimp. Cage breeding has a higher yield and can achieve a harvest of two crops a year. Freshwater shrimp is a crustacean that lives on the bottom of the water. Raising freshwater shrimp in the same pond with fish can fully utilize the potential of the water body and increase economic benefits. Freshwater shrimp is a pure freshwater product, living in rivers, lakes, ponds and ditches. It lives in deep water in winter and moves to the shore after the water temperature rises in spring. In summer, it feeds and reproduces in the dense water grass along the coast.

The spawning period is from April to early September, with the peak period being June and July. The suitable water temperature is 18-28℃. Female shrimps that have overwintered can spawn twice in succession between April and July. When the first eggs hatch, the ovaries are mature again, and then they molt, mate and spawn for the second time. The interval between the two spawning is about 20-25 days. Among the new shrimps of the year, some shrimps (generally 24-35 mm in length) become sexually mature and carry eggs in August, but their offspring cannot spawn in the same year.

When the female shrimp's ovaries mature, they are brown-green, and the edges of the side armor on the abdomen are light yellow and open to both sides. Mating takes place before the female shrimp lays eggs. Before mating, the female shrimp generally molts first. During mating, the male shrimp hugs the female shrimp, with the ventral surface of his body pressed against the ventral surface of the female shrimp, lying on the bottom of the water or on water plants, and then the male shrimp releases spermatophore. The mating time is very short. After mating, the female shrimp generally lays eggs within 24 hours. The time of spawning is mostly before dawn. All mature eggs in the ovary are laid at once.

The number of eggs carried is proportional to the body length. Female shrimp with a body length of more than 45 mm carry between 1,500 and 4,000 eggs; those with a body length of less than 45 mm carry 700 to 2,000 eggs; and the egg-carrying shrimp in the new shrimp population of the year (body length 24 to 35 mm) carry between 200 and 500 eggs.

The ratio of male to female shrimps is usually about 10:7, but during the peak spawning period, the ratio of male to female shrimps can drop to 10:4 because male shrimps die soon after mating. Female shrimps also die one after another after the end of reproduction, so the life span of green shrimps is generally only about one year. The gonads are located above the digestive glands in the head and thorax. The testes are white and slightly yellow, with an uneven surface. It has two lobes in the front part and merges in the back part. There is a pair of long and tortuous vas deferens, which eventually opens on the inner side of the base of the fifth pair of walking legs (Figure 1). Sperm is in the shape of a thumbtack. The width of the head is about 11.5-16.1 microns and the length is about 5.75-6.9 microns. The tail is about 10.35-16.1 microns long (Figure 3). Sperm is inactive in both the testes and the vas deferens. When mature sperms pass through the vas deferens, they are coated by the secretions of the vas deferens to form sperm capsules. The sperm capsule is a milky white translucent gelatinous body. After mating, the spermatophore adheres to the base of the 3rd to 5th pairs of legs of the female shrimp.

The ovary is oval, with a slightly pointed front end and two lobes, and a blunt back end without lobes. The mature ovary is brown-green, with a relatively smooth surface, and has a pair of short and straight fallopian tubes on both sides.

The opening is on the inner side of the base of the third pair of legs (Figure 2). The back of the ovary has branched blue and orange pigments. The mature ovary is very soft, with a thin membrane, and is easily broken during dissection.

The ovaries do not develop between October and January of the following year, and begin to develop after February as the water temperature rises. In March, most eggs begin to accumulate yolk and the egg diameter continues to expand. By late April, a few female shrimps have mature ovaries and lay eggs.

The eggs are oval in shape. After being laid, they are attached to the 1st to 4th abdominal legs of the female shrimp (many bristles appear on the abdominal legs to attach the eggs). When the eggs are just laid, the diameter of the eggs is 0.55-0.57×0.65-0.68 mm. The diameter of the eggs before hatching is about 0.65×0.80 mm. The color of the eggs in the early stage of development is darker, yellow-green or brown-green, and then it becomes lighter and lighter as it develops, from yellow-green or brown-green to light yellow. The eggs that are about to hatch are almost transparent and colorless except for the two compound eyes. The degree of firmness of the connection between eggs is also different at different stages of development. At first, the connection is firm, but in the late stage, they are easily separated from each other and easily fall off from the mother. The eggs of the green shrimp are medium-yellow eggs with a lot of yolk. On the morning of May 12, 1963, the author caught a female shrimp with sperm pods and kept it in a culture tank. At 5:10 on the 13th, it was checked that it was already holding eggs. The eggs are soft, fragile, have no dividing surface, and are full of yolk. The egg's long and short diameters are about 0.65-0.68×0.55-0.57 mm. The nucleus is located in the center of the egg, surrounded by radiating protoplasm. This egg is a fertilized egg, estimated to have been laid 1-2 hours ago (Figure 4). After that, a few eggs were picked at appropriate intervals for observation, and the outline of its embryonic development is as follows: At 6:00 on the 13th day, the nucleus split into two and separated from each other along the long diameter of the egg. The protoplasm also split into two after the nuclear division and moved with the nucleus. No obvious dividing groove can be seen on the surface of the egg. This is the first cleavage, the two-cell stage.

At 8:00, the nucleus splits into four, but the four nuclei are not on the same plane. A not very obvious segmentation groove can be seen on the surface of the egg. The embryo has the characteristics of spiral segmentation (Figure 6). At 9:30, the egg splits into eight, which is the third cleavage, the eight-cell stage. At this time, the eight nuclei and the protoplasm around them are close to the surface of the egg, and are located in the center of each segmentation surface, which can be clearly seen. From the third cleavage, due to the influence of spiral segmentation, the arrangement of the segmentation balls is very irregular, and the arrangement of the segmentation balls in eggs of the same cell stage is often different. As the cleavage proceeds, the cell nucleus gradually moves to the surface of the segmentation ball, and the segmentation ball becomes smaller and smaller, and becomes polygonal due to mutual compression. The fourth cleavage is completed at 15:10, and it is the sixteen-cell stage.

At 17:00, the fifth cleavage was completed, and the ovum was at the 32-cell stage. At 7:00 on the 14th, it was at the blastocyst stage (Figure 8). At 20:00, the dividing surface became smaller and less clear. At 20:10 on the 15th, the original mouth appeared.

The gastrula phase begins. One side of the egg becomes concave inward, shaped like a mouth (Figure 9). After 3-4 hours, the gastrula disappears.

The nauplius stage appears at 10:00 on the 16th. At this time, a transparent and colorless piece appears at one end of the egg, where there are two larger protrusions, namely the upper lip and the thorax and abdomen primordium.

The three pairs of small papillae in the middle are monopodial and are the buds of the large antennae, small antennae and mandibles (Figure 10).

After the nauplius stage, the embryo undergoes complex changes and develops slowly. Most embryos enter the metanauplius stage on the 17th day.

The yolk is less than that of the previous stage, the primordium of the upper lip and the thorax and abdomen is enlarged, and the abdomen appears but is not segmented. There are about 5 pairs of appendages, which are bipedal, but they are all primitive papillary protrusions. Behind the last pair of appendages, there is a small pile of oil-like spots, and the heart will soon appear here. The cephalothorax has taken shape (Figure 11). Around the 20th day, compound eyes appear, which are first strip-shaped and then gradually expand into a crescent shape. There are two large branched orange-red pigments near the compound eyes. The unsegmented abdomen is extended and bent toward the head. There are 5 pairs of appendages, which are bipedal. The tail (the end of the body) is forked. The heart beats irregularly. The embryo at this time is still in the post-larval stage.

⒋ The post-embryonic development of green shrimps lasts for 9 molts in the first 20 years. This paper only describes the larvae after the 8th molt.

On June 8, 1963, the eggs hatched and became the first stage larvae, and on June 10, they molted for the first time and became the second stage larvae. After that, they molted every 3-4 days, and by July 9, they had molted a total of eight times and became the ninth stage larvae.

First-stage larvae (Figure 14): Body length (from the rear edge of the compound eyes to the end of the body) is about 2.2-2.4 mm. The compound eyes are sessile and inactive. The forehead is short and has no teeth on the upper and lower edges.

The first antennae have an unsegmented peduncle; the outer limbs are short and thick, with 4-5 feathers at the end; the inner limbs have a single slender feather. The second antennae have a flat outer limb, with 7 feathers and 2 short spines arranged on the inner edge; the inner limbs are shorter and club-shaped, with a long feather and a short spine at the end.

The mandible is arc-shaped, with 4-5 teeth, without distinction between incisor and molar parts.

The first maxillary limb has a spine at the end, and the inner limb is short and spineless. The second maxillary limb has 3-4 protuberances, each with 2-3 spines at the end, and the inner limb is small.

There is a sting at the end; the outer limb is wide, also called the maxilla, with 3-4 long feathers on its front edge and a long feather and a short sting at the rear end. When alive, the constant fluctuation of the maxilla keeps the water in the gill chamber flowing, which is beneficial for breathing.

The inner limb of the first maxillary peduncle is short and unsegmented, with a stinging hair at the end; the outer limb is long, with 4 feathery hairs and 2 short feathery hairs at the end; the base limb is divided into 2 segments, slightly swollen on the inside, and there is a small protrusion on the outside of the first segment, which is the bud of the gills. The inner limb of the second maxillary peduncle is divided into 4 segments, the last segment is claw-shaped, and there are 3-4 short spines at its base; the outer limb is the same as the first maxillary peduncle. There are 3-4 short hairs on the inside of the base limb. The third maxillary peduncle is similar to the second maxillary peduncle, but larger.

The first and second walking legs are bifurcated, unsegmented, and without spines. The third, fourth, fifth walking legs and ventral legs have not yet appeared. The tail segment is not separated from the body, is triangular, and has 7 pairs of tail hairs on the rear edge.

The larvae move in the water with their heads down and their tails up, moving backwards. They are phototactic and like to gather on the water surface, especially at the edge of the container. They rely on yolk for nutrition and do not eat.

Second stage larva (Figure 15): 2.5-2.6 mm long. Eyes are stalked and movable. There is a pair of supraorbital spines on the front edge of the cephalothorax. There is a pair of spines on both sides of the rear edge of the sixth abdominal segment.

The first antennal peduncle has two segments, with stings on the inner side. The toothed part of the front edge of the maxilla is enlarged. The first and second maxillae are slightly enlarged, with more stings. One sting is added to the end of the inner limb of the first maxillopod; 4 stings appear on the inner edge of the base limb. The second maxillopod has no obvious changes. The inner limb of the third maxillopod has 5 segments.

The first and second walking legs have 5 segments, each with 1-2 stings, and the last segment is claw-shaped. The tail limbs have not yet appeared. The shape of the tail is similar to the previous period, with only 2 short stings added to the central depression of the rear edge.

The movement of the larvae is similar to that of the previous stage. The main locomotion organs are the external limbs of the maxillopods. The nutrition is still mainly egg yolk, but they have begun to eat a small amount of food. The objects of food are mainly lower algae. The main feeding organs are the mandibles and maxillae, and the maxillopods and walking legs have auxiliary functions.

The third-stage larva (Figure 16): 2.7-2.8 mm long. There is one tooth at the base of the forehead.

The first antennal peduncle has three segments, with four feathers on the inner edge, and the outer side of the first segment is slightly curved. The second antennal exopod is enlarged, with 16 feathers; the inner peduncle is divided into three segments, with 4-5 stings at the end. The maxilla, maxilla and maxillopod have no significant changes. The first and second walking legs are enlarged, and the last segment is longer. The third walking leg appears, which is bifurcated, unsegmented, and has no stings.

The fifth leg is a single limb, relatively large, unsegmented, and without stinging hairs. The tail segment is separated from the body, with 7 pairs of tail hairs on the rear edge. The tail limb is present, with 6 feathery hairs on the outer limb and small, hairless inner limb.

The yolk disappears and the baby relies entirely on food for nutrition. In addition to eating lower algae, it also eats dead water fleas and other animal food such as larvae of the same species. Nutrition at this stage is extremely important.

If there is a lack of adequate palatable food, a large number of larvae will die during the next molting. The activity range of the larvae has expanded and their phototropism has weakened.

Fourth-stage larvae (Figure 17): 2.9-3.1 mm in length. The inner side of the first antennal stalk has 7 feathery hairs, and the outer side of the first segment expands outward. The inner limb of the second antenna is divided into 3 segments, and the outer limb has 15-16 feathery hairs. There are no significant changes in the mandibles, maxillae, and maxillopedis.

The inner limbs of the first and second walking legs are longer, the palmar segments are thicker than the previous stage, and the phalanges are shorter. The inner limbs of the third walking leg have 5 segments, which are about the same length as the outer limbs; the outer limbs are not segmented, and there are 4 long feathers at the end. The fourth walking leg has buds. The fifth walking leg is the longest, with 5 segments and no outer limbs. The tail segment becomes narrower and trapezoidal, with 4 pairs of tail hairs and 2 pairs of short spines on the rear edge. The outer limbs of the tail limbs have 9-11 feathers, and the inner limbs have 6-7 feathers.

The fifth stage larva (Figure 18): body length 3.4-3.6 mm. There are 11-12 feathery hairs on the inner and front edges of the first antennal stalk. On the outside of the first segment, the stalk spines have formed.

There are many fine hairs near it. The inner limb of the second antenna still has 3 segments, and its length is about the same as the outer limb; the outer limb is wide, with 18-19 feather-like hairs on the edge. The first maxilla is well developed,

There are 6-7 thick spines on each of the two basal limbs. The first and second walking legs are relatively thick, and the palm section is relatively thick. The inner limb of the third walking leg is longer than the outer limb. The fourth walking leg appears and is bifurcated.

Unsegmented, without spines. The buds of the ventral foot are already present, shaped like tumorous protrusions. There are 2 pairs of short spines on both sides of the tail segment, and 4 pairs of tail hairs on the rear edge. The outer limbs of the tail limbs have 15-16 feathery hairs, and the inner limbs have 11-12 feathery hairs.

The sixth stage larva (Figure 19): body length is about 3.9 mm. There is no obvious change in the antennae and maxillae. The outer limb of the first maxillae is short and thick; the number of spines at the end of the inner limb and the inner side of the base limb is increased compared with the previous stage.

The second and third maxillary legs and the first, second and third walking legs have little change. The fourth walking leg is of normal shape, with the inner limb divided into 5 segments, longer than the outer limb. The abdominal limb is bifurcated and has no spines. The outer limb of the tail limb has feathers.

There are 19-20 hairs, 14-15 on the inner limbs.

The seventh stage larvae are similar to the previous stage with no significant changes.

The eighth stage larva: body length 4.9-5.1 mm. The first antenna has three whips: inner whip, outer whip and auxiliary whip. But they are all very short and not segmented. The stalk is very large.

The second antennae have 8-10 segments, the last two of which extend beyond the front end of the scales. The base of the first maxillary limb is enlarged outwards, with spines on the edge; the inner limb is short and

Unsegmented, with 5-6 spines; basal limbs divided into 2 pieces, quite broad, with many spines. The first and second walking legs are thick and primitive pincer-shaped.

Each of the other segments has 1-3 spines. The third and fourth ambulacral legs are similar to the sixth and seventh stages. The fifth ambulacral leg grows significantly, with two additional spines on the inner side of the palm. The ventral legs are hairless, except for the first ventral leg, which has internal appendages. The tail segment is pointed and has two pairs of dorsal spines in the posterior half; the end has a pair of posterior horn spines and four pairs of tail hairs, of which the outer pair of tail hairs are the thickest and longest.

The larvae still move in the water with their heads hanging upside down.

The ninth stage larvae: 5.5-6.5 mm in length. The forehead is slightly curved, with 11-12 teeth on the upper edge and 1-2 teeth on the lower edge. The larvae have become benthic and can crawl or swim horizontally.

The inner whip of the first antenna has about 10 segments; the outer whip is about 1.5 times longer than the inner whip; the secondary whip is short and thick with 3 segments. The length of the second antenna whip is more than 2 times that of the scales.

The first maxilla is completely similar to the adult shrimp, with 8-9 spines at the end of the two basal limbs, and a protrusion and a short spine at the end of the inner limb. The two basal limbs of the second maxilla are slender, slightly curved inwards, and far away from the inner limbs; the inner limb is one piece and hairless; the outer limb (maxilla) is very developed and has many stings. The first maxillary peduncle has well-developed basal limbs, and the inner limbs are small and hairless. The second maxillary peduncle has short outer limbs that curve inwards; the inner limb is short and has 4 segments; the gills are well developed. The third maxillary peduncle has short outer limbs; the inner limb has 3 segments. The first and second ambulacral legs still have remnants of outer limbs. The third, fourth, and fifth ambulacral legs have disappeared. The first abdominal leg has short inner limbs with 2 stings at the end; the outer limbs are wide and have 12-13 feathery hairs. The outer limbs of the second, third, fourth, and fifth abdominal legs are similar to the first abdominal leg, but the inner limbs are larger, with many feathery hairs on the edges, and inner appendages on the inside.

Self-breeding and self-raising of seedlings is the fundamental way to improve shrimp production, and correctly mastering breeding techniques is the basis for self-breeding and self-raising.

(I) The water temperature required for spawning of broodstock during the spawning period is above 18°C. The peak spawning period in the middle and lower reaches of the Yangtze River is from mid-April to mid-September, and from June to July, with the peak period from mid-June to mid-July.

(II) Spawning and Hatching In the spawning group, the broodstock that spawns in June and July are larger, and they are old shrimps that have overwintered; the broodstock that spawns after July are smaller, and they are shrimps that have grown up after reproduction in the same year. The whole process of spawning and hatching is carried out in the net cage. The net cage is divided into two types: breeding box and hatching box. The breeding box is made of polyethylene mesh with a mesh of 196 mesh/square centimeter, with a specification of 10 meters x 667 meters x 1.7 meters. A polyethylene rod rope is installed at the bottom and top of the box. The net cage is open and floating. When installing, 0.3 meters of the net cage is exposed above the water surface to prevent shrimps from escaping. Place 1-2 small wooden dyeing net cages for hatching in the box. They are made of polyethylene mesh with a mesh of 12 mesh/square centimeter, with a specification of 1.7 meters x 1 meter x 0.5 meters. When installing, the net cage is exposed 5 centimeters above the water surface, and a small brick is tied to each of the four corners of the bottom of the box.

Parent shrimps should be moved to a breeding box for fattening before spawning. When the water temperature reaches 18℃, parent shrimps will mate and usually spawn within 24 hours after mating. When female shrimps are about to give birth, their abdomens stretch and bend, and their backs rise.

The eggs produced are oval in shape, with a lot of yolk, and are attached in groups to the 1-4 pairs of bristly appendages on the female shrimp's abdomen. Old shrimps that have overwintered can lay eggs twice in a row, with the second spawning occurring after the first eggs hatch. The number of eggs laid by green shrimps is related to the age and body length of the parent shrimps.

Age shrimps can lay up to 5,000 eggs, while shrimps that mature in the same year are 3 cm long and can only lay about 700 eggs at most.

When compound eyes appear on the eggs, the female shrimps with eggs should be placed in small hatching cages, with 700-1000 shrimps in each cage. After 6-7 days, the larvae will break the membrane and fall into the incubator. At this time, the hatching box and the shrimps that have laid eggs should be taken out of the cages.

Reproduction and seed cultivation of freshwater shrimp

1. Cleaning and disinfection of shrimp ponds

The shrimp pond should be well ventilated and sunny, with sufficient water, an area of ​​667-1334 square meters (1-2 mu), and a water depth of 1-1.5 meters. In actual breeding, there should generally be 2-3 such shrimp ponds for coordinated use. Before breeding, the shrimp pond should be cleaned, excess silt should be removed, the bank should be heightened and reinforced, and the pond should be shallow around the edges.

Medium depth; secondly, disinfect the shrimp pond. For every 667 square meters, use 100-150 kg of quicklime to make a slurry and sprinkle it all over the pond while it is hot, or for every 667 square meters with a water depth of 1 meter, use 15-20 kg of bleaching powder or 1.5-2 kg of sodium pentachlorate to make a slurry and sprinkle it all over the pond to kill the pests and diseases in the pond.

Before releasing the brooding shrimps, plant water peanuts or other aquatic plants 1 meter away from the pond edge and secure them with ropes or nets to form a water weed belt. The area of ​​the water weed belt should account for 20% to 30% of the water surface.

2. Incubation method

It is ideal to cultivate shrimps with eggs in cages, and the parent shrimps can be retrieved. The hatching cage is made of polyethylene mesh, a small cage of 2m x 1m x 0.8m, with a mesh size of 0.8cm, fixed in the pond, and 0.5-1kg of shrimps with eggs are placed per square meter, and 4-5kg are placed per 667 square meters. The shrimps with eggs should be selected from female shrimps that are caught in unpolluted outer river waters, with a body length of more than 5cm and a relatively close degree of egg development. The specific method of hatching is: put 2-3 times the shrimps with eggs into the first pond for hatching, and when 1/3 or 1/2 of the shrimps with eggs are emptied, move the remaining shrimps with eggs and the cages into the second pond for further hatching, and then move them into the third pond to let all the shrimps with eggs be emptied.

3. The following tasks should be done during the cultivation stage of the hatched shrimp fry

⒈Basic bait cultivation

During the incubation period, samples should be taken regularly to check the brooding shrimps. When the color of the fertilized eggs changes from orange to gray-brown and eye spots appear, it indicates that they are about to hatch. Organic fertilizers should be applied to the pond to cultivate plankton for the larvae of the shrimps. Generally, 150-250 kg of sterilized and fermented livestock and poultry manure should be applied per 667 square meters. A large amount should be applied to newly excavated ponds, and a small amount should be applied to old ponds as appropriate. In the future, water changes and topdressing can be used to promote the reproduction of bait organisms, maintain the density of palatable bait, and ensure the supply of fresh bait for the larval stage of the shrimps.

⒉Injection and water change

After the larvae hatch, add new water once a day or every other day, raising the water level by 5-7 cm each time to keep the water fresh and high in dissolved oxygen. After 10 days, generally add water once every 5-7 days or change the water once, and the amount of water changed is 1/4 of the pond water; in hot seasons, change the water every other day. The pond water should not be too deep, otherwise it will affect the growth of plankton and easily cause hypoxia at the bottom of the pond. The highest water level should be controlled at 1-1.5 meters. The water inlet is double-wrapped with 60-80 mesh sieve silk to prevent harmful organisms from entering the pond with water.

⒊ Apply topdressing

Depending on the water quality, top dressing is usually applied once every 5 to 7 days, with 75 to 100 kg of decomposed livestock and poultry manure or 1 to 2 kg of inorganic fertilizer plus calcium phosphate per 667 square meters to keep the water rich, active and refreshing, and the water transparency maintained between 30 and 40 meters.

4. Baiting

From the second day after the zoeae leave the mother's body, they need to absorb external nutrition to maintain the energy needed for their growth and activities. From the zoeae to the juvenile shrimp, they are mainly fed with natural bait (plankton) and artificially fed soybean milk and egg yolk. While cultivating the basic bait for the juveniles, they must also be supplemented with an appropriate amount of artificial bait every day. In the early stage, 1-1.5 kg of soybean milk filtered with sieve silk or 4-6 crushed and filtered cooked egg yolks are fed every 667 square meters every day. The speed of feeding egg yolks should be slow because egg yolks are easy to sink. The feeding time is divided into 3 times a day, 8 am, 4 pm, and 12 pm. Most production units feed twice a day, that is, 8-9 am and 5-6 pm. Several fishing nets can be set up in the pond to check the feeding situation.

5. Water disinfection

During the larval cultivation period, 15-20 kg of quicklime should be made into a slurry and sprinkled throughout the pond while it is still hot for every 667 square meters and 1 meter of water depth every 10 days. This can not only adjust the pH value, but also disinfect the water, supplement calcium, and help the shrimp grow and molt.

⒍Timely pond division

After 20-30 days of cultivation, the larvae molt several times, the appendages on the chest and abdomen are fully developed, and the appearance is the same as that of adult shrimps. When the body length reaches about 1 cm and the swimming and jumping ability is strong, they should be caught and separated into ponds in time for adult shrimp farming. When pulling the net, the action should be slow to prevent the young shrimps from suffocating and dying by sticking to the net.

Through the above management methods, generally speaking, every kilogram of overwintering shrimp with eggs can produce about 100,000 young shrimps with a body length of about 1 cm.

High-efficiency shrimp cage culture technology

Freshwater shrimp is an economic shrimp with a wide distribution in China's freshwater waters, a variegated diet, fast growth and strong reproductive capacity. In the past, most of them were wild, but artificial breeding has been carried out in many areas. Cage culture of freshwater shrimp has the characteristics of short breeding cycle, high survival rate, quick results and good benefits. It is a very promising breeding method and an important way to develop and utilize large water surface resources. The author guides agricultural production to utilize large water surfaces such as rivers, lakes and reservoirs, and give full play to the advantages of fresh water quality and sufficient dissolved oxygen in the water body to carry out efficient cage breeding of freshwater shrimp, and has achieved good results. The summary is as follows, hoping to help freshwater shrimp breeding.

Living habits:

Frogs live on land and in water. They mainly feed on some agricultural pests, and each frog eats more than 60 pests every day. The body color of frogs living in ponds with dense aquatic plants is grass green, and the body color of frogs living in ditches without green grass is gray-brown. The body color of frogs is relatively consistent with the color of the environment, which can play a good protective role so that they can live better in water and on land. Appearance characteristics:

The frog has four toes on its front feet and five toes on its back feet, and webbed feet. There are two slightly bulging small bags on both sides of the frog's head. That is its eardrum, through which the frog can hear sounds. The frog's back is green, very smooth, very soft, and has patterns, and its abdomen is white. It can hide in the grass, making it easier to catch pests and protect itself. Its skin can also help it breathe. Its air sacs are only found in male frogs. Frogs use their tongues to hunt, and there is mucus on their tongues. Frogs are oviparous, and the eggs hatch into tadpoles and finally become frogs. The frog's body is divided into three parts: the head, the trunk, and the limbs, and the skin is smooth. In terms of movement and hunting, it is: swimming, jumping, and hunting with the tongue. In terms of reproduction and development, it is: oviparous, and developmental metamorphosis. Its living environment is: it can only live in water when it is young, and it can live on land when it grows up. In addition to making great contributions to agricultural production, frogs have other uses.



Additional information:

Frogs are amphibians. The most primitive frogs began to evolve in the Triassic period. They belong to the animal kingdom, phylum Chordata, class Amphibia, order Anura, suborder Eorhinaria, suborder Mesorhinaria, and suborder Neorhinaria. The earliest frogs that can jump appeared in the Jurassic period. Because frogs mainly feed on insects and other invertebrates, they must live near water.

Anura is an order of animals belonging to the class Amphibia. Adults are basically tailless. Eggs are usually laid in water and hatch into tadpoles, which breathe with gills. After metamorphosis, adults mainly breathe with lungs, but most of them also have some breathing function through their skin. There are mainly two types of animals: frogs and toads. There is no strict distinction between these two types of animals, and some families include both.

Anura is the first step for organisms to move from water to land. It is more advanced than other amphibians. Although most of them can live out of water, they still cannot reproduce without water. The eggs need to undergo metamorphosis in water to grow. Therefore, it is not as advanced as reptiles, which can live completely out of water.