Extended data
nutritive value
Portunus is tender and white, rich in protein, fat and various minerals. Swimming crabs are the strongest in winter, generally weighing about 250 grams, up to 500 grams.
The red mud of the female crab is covered and tastes excellent. Swimming crab can be eaten fresh, steamed, fried or fried, or stewed in bean paste, or fried with crab to make rice cakes, pickles and tofu, which are common dishes on the table of residents in coastal areas.
It can also be pickled, that is, the fresh Portunus trituberculatus is soaked in brine and can be eaten in a few days, commonly known as "fresh wind catching crabs". In the past, due to the high yield of Portunus trituberculatus, fishermen often chose live crabs covered with paste, put yellow in bowls, and let them solidify in the wind, rain and sun to become "crab yellow cakes", with excellent flavor, but low yield, which is difficult for ordinary people to taste.
reproductive period
The mating season is April-May to early winter in the Yellow Sea and Bohai Sea, and March-April to11~ 65438+February in the coastal areas of Fujian. In addition to sexually mature individuals, immature females can sometimes accept mating.
From April to May every year, female crabs migrate and gather in coastal shallow harbors or near estuaries to breed, and the fertilized eggs laid are held on the abdominal limbs of the abdomen. Each female crab can lay two or three eggs in the breeding season, totaling several hundred thousand to two million eggs. Newborn eggs are yellow and turn dark brown after about two weeks.
economic value
Rich in meat, full of fat paste, delicious and nutritious. Every100g of crab contains protein14g and 2.6g of fat. Fresh food is mainly steamed, and salt can also be added to "choking crab" and crab sauce. After being rinsed and dried, crab eggs become "crab eggs", all of which are top-grade seafood.
The warm temperate perennial crab is the largest crab in China. He is good at swimming and dredging, often lurking near the seabed or estuary, fierce and aggressive, with strong reproduction and rapid growth.
At the end of March, crabs swam to shallow water to lay eggs, and the largest individual of spawning crabs reached 750 grams. The peak of spawning is in the middle and late April, and it usually takes three years from the first juvenile crab stage to the mature stage. Female crabs account for more than 80% in inshore spawning grounds, and there are more male crabs in the open sea. The main fishing season is in April.
According to the old fisherman, the temperature in the wintering period or the water temperature in the wintering field has a great influence on the catch of Portunus trituberculatus. The crabs around Grain Rain are the most plump. Although they can be caught in autumn, they are not full (but the male crabs before wintering are particularly plump, so they are called "male crabs after stubble").
Male crabs are commonly called "pointed umbilicus", immature male crabs are called "hooked umbilicus" and female crabs are commonly called "round umbilicus". The female crab is the best, and the big crab with eggs is also called "pomegranate yellow". The market prices of male crabs and female crabs are quite different.
Crab meat is white, fleshy, tender, smooth and delicious. In particular, the shredded pork with two pincers' pincers' feet is smooth and sweet, fragrant with crab yellow, unique in food, and has a long-standing reputation, ranking first in seafood.
As Li Yu said in the Qing Dynasty, "The crab is fresh, fat, sweet and greasy, as white as jade and as expensive as gold, and everything is offered." Every100g of meat of Portunus trituberculatus contains protein14g, 2.6g of fat and some other nutrients.
The general eating method is steaming, and the meat is dipped in Jiang Mo vinegar juice, with alcohol, which has a unique flavor. Bai Juyi, a great poet in the Tang Dynasty, said that "the bear's paw is rotten in Luzhen, and the seafood crab pinches", and compared the crab's paw to the bear's paw.
In addition to fresh food, it can also be dried into crab rice, ground into crab paste, pickled whole crabs (marinated crabs) and canned. Crab shell can be used as raw material of chitin, and the economic benefit is very considerable.
Due to overfishing in recent years, the natural resources of Portunus are also decreasing. In order to meet the market demand and properly protect resources, artificial farming has been carried out in some coastal areas in recent years.
According to reports, the earthen pond is the most suitable for breeding. The structure of the pond is similar to that of the intensive shrimp pond, and the area is suitable for small and medium-sized ponds. The water depth is 1.5 m ~ 2 m, and the water quality remains good. Spread coarse sand and a hidden place at the bottom of the pond to let it live.
The seedlings of the same specifications must be stocked in the same nursery pond to avoid killing each other. Another method is that after mating in autumn, the caught thin crabs are stored in a soil pond and fed to small miscellaneous fish and shellfish. , promote fattening, and harvest in early winter to supply the market.
brief introduction
Portunus trituberculatus, commonly known as Portunus trituberculatus and White Crab, belongs to Portunus family of crustacea, and is an important economic crab in China's coastal areas. Its rapid growth and rich breeding profits make it an important breeding variety in coastal areas of China.
Portunus usually lives and breeds on the seabed of 3-5 meters, migrates to the deep sea of 10-30 meters in winter, and likes to make holes at the bottom of sediments.
Its adaptive salinity is 16-35, water temperature is 4℃-34℃, PH value is 7-9, optimal salinity is 26-32, and optimal temperature is 22℃-28℃. Water quality requires fresh and high dissolved oxygen. When the environment is not suitable or the shelling is not complete, there is a phenomenon of self-cutting, and the feet can be regenerated after being cut off.
Portunus 1 species of Portunus, a suborder of Portunus, is named for its spindle-shaped head and breastplate and three prominent wart processes in the stomach back and heart area. There are more than 50 species of Portunus in the Indo-Western Pacific, and there are 17 species in the coastal areas of China. This species is found in China, Japan and Korea.
The front side edge is obliquely arched, with 9 sharp teeth and a thorn at the end of the rear edge. The fourth step (the last step) is that the metacarpals and knuckles of the foot are paddle-shaped, which is a swimming foot. The abdomen of male is in the shape of Yangtze River Delta, and that of female adult is nearly round.
Portunus trituberculatus lives in soft mud, sand mud under rocks or aquatic plants with a water depth of 7 ~ 100 meters near the shore. A small number of small or medium-sized individuals can also be obtained at the low tide line in the intertidal zone. They usually crawl slowly on the seabed with the fingertips of the first three pairs of feet, swim with their swimming feet, or move forward or backward sideways.
References:
Baidu encyclopedia-sea crab