In recent years, Dongting Lake has also become the main producing area of crayfish. At the same time, it is also a typical representative of inland lake, the main producing area of crayfish in China. Recently, we also made a special trip to Dongting Lake to investigate the growing environment of crayfish.
1. What is the growth environment of crayfish? What kind of environment is most suitable for the growth of crayfish?
In Yuanjiang section of West Dongting Lake, we found Lao Gan, a shrimp farmer. Lao Gan told us that crayfish would move in the shallows every summer. In winter or when crayfish shell and breed, in order to protect themselves, crayfish will lurk in caves. Every year from June to August, it is the most "plump" time for crayfish, and it is also the best time for people to catch and enjoy it. Green wormwood, shallow water beach, this water area is where Lao Gan often catches lobsters.
Shrimp farmers say that crayfish like to live in clean places, such as the gutter, where crayfish don't grow up.
The survey shows that the rumor that crayfish grow better in dirtier places is unfounded.
Second, are there many crayfish sold in the market at present?
Crayfish is an omnivore, which mainly eats animals. Small fish, shrimp, plankton, benthos and algae can all be used as its food. According to shrimp farmers, crayfish are very fertile, and they ovulate two or three times a year. It usually takes only 2 months from the hatching of shrimp eggs to the maturity of crayfish.
The shrimp farmer said that when he was alone at most, he could get three or four hundred Jin, but there were thousands of shrimp farmers like him in Dongting Lake waters. Every day, there are about 30 tons of crayfish sent from Yuanjiang market to all parts of the country.
The water area with shallow water plants is the favorite of crayfish, because it is not only their habitat, but also a hidden place for them to shell. In addition, crayfish also like to drill holes, and their destructive ability is also very strong. They often break through the ridges and destroy the dams. Combining these characteristics of crayfish, local shrimp farmers have specially made a kind of shrimp catching tool-the Earth Dragon King. Shrimp farmers set a net hole in each section of the Earth Dragon King, which is simple and convenient, but can invite shrimps into the urn.
Shrimp farmers say there is no need for artificial breeding because crayfish have strong reproductive ability.
The survey shows that wild crayfish can meet the market demand, and the cost is much lower than that of artificially cultured crayfish. Artificial culture of crayfish has no economic benefits. Therefore, there is no basis for saying that the environment of artificially cultured crayfish is bad.
3. Are there many crayfish caught from the river ditch?
June, July and August are the best seasons to catch crayfish in Dongting Lake every year. In late August, as the temperature of the lake drops, crayfish begin to dig holes at the bottom or shore of the lake to wait for the next summer. At this time, the shrimp fishing on the lake has gradually reached a low point, while the number of people catching shrimp in the river ditch has increased.
The tools for catching shrimps in river ditches are very simple. Shrimp farmers usually only need a shovel for digging and a glove for catching shrimps.
Shrimp farmers say that the water in the cave is very clean, which is the same as the growth environment of eel and loach. The holes dug by crayfish are generally between 1.5 and 2 meters, and the weather is getting cold after autumn, so it is more difficult to dig crayfish in the river ditch, which is only six or seven kilograms a day.
The investigation shows that the time suitable for catching shrimp in the river ditch is very short because of the cold weather. And there is not much economic benefit. Therefore, most of the crayfish currently on the market are crayfish caught in the lake area.
Fourth, how to distinguish the crayfish dug in the river ditch from the crayfish caught on the lake?
When we asked about the difference between lake shrimp and ditch shrimp, Lao Gan, a shrimp farmer, made a comparison between lake shrimp and ditch shrimp. The crayfish raised in clean water are larger, the shrimps in the lake are lighter and redder, and the shrimps in the ditch are darker.
Tip: Because of the different growth environment of crayfish, it is suggested to eat crayfish produced in the lake area. The crayfish produced in the lake area are characterized by bright colors, large individuals, and the proportion of head to trunk is relatively consistent.
At present, crayfish sold in China's market are mainly produced in Dongting Lake, Poyang Lake, Honghu Lake and Hongze Lake. Taking Dongting Lake as an example, the daily output in peak season is about 30 tons, and it is about 3,600 tons in four months in 5678. Together with other lake areas, the total output of these major producing areas in peak season is around 1 17,000 tons. This is basically the same as the current annual consumption of 20,000 tons of crayfish in China.
Because of the high content of protein in crayfish, the content of trace elements such as zinc, iodine and selenium in shrimp meat is also higher than other foods. And the taste is good, so crayfish is very popular in many cities in recent years. Some places even set off a "red storm" of summer catering. But our reporter also has some worries, because the situation in some waters where crayfish are produced is not optimistic.
During the investigation in Dongting Lake waters, we found that there was a stone tablet standing in the aquatic products trading market in Yuanjiang City, saying, "There is schistosomiasis here, so it needs to be protected when entering the water." So if crayfish live in such waters, is it possible to become the parasitic host of schistosomiasis? To this end, we visited Yuanjiang Health and Epidemic Prevention Bureau. The director told us that Schistosoma japonicum is only parasitic among snails, and no evidence of Schistosoma japonicum parasitic among crayfish has been found yet. But experts also confirmed that crayfish is indeed the intermediate host of paragonimiasis.
5. Could crayfish possibly carry parasites and heavy metals?
We sent crayfish brought from Dongting Lake waters and crayfish bought from Beijing market to the Institute of Tropical Diseases of Beijing Friendship Hospital for testing.
The investigation shows that there is no evidence that crayfish carry schistosomiasis, paragonimiasis or are polluted by heavy metals. In addition, both schistosomiasis and paragonimiasis are afraid of high temperature. Therefore, crayfish can be safely eaten as long as they are cooked at high temperature.
6. How do shrimp farmers make crayfish?
First, rinse and soak in cold water for one or two hours, and then remove the head, breastplate, head and cheeks of the shrimp. Next, remove the shrimp intestines from the tail fan. After cutting open the shell of the crawfish's abdomen, finally, comprehensively scrub the crawfish. As for the cooking method, it is based on personal preferences, and so on.
Tip: Shrimp farmers have a better understanding of the habits of crayfish, and their methods of making crayfish are more scientific and can be used for reference.
7. There are many frozen products of crayfish or shrimp tails of crayfish that have been prepared for sale in the market. Are these products fresh?
During the investigation, we also found some situations like this.
Phenomenon 1: Some shrimp vendors pinch their heads and leave their tails for sale as frozen products.
Phenomenon 2: In some markets, there are shrimp vendors selling dead crayfish.
Tip: Be careful to buy and eat frozen crayfish of unknown origin or prepared shrimp tails. Because these products may not be very fresh.
In order to make everyone enjoy crayfish more healthily, here are some suggestions.
Suggestion 1: Make your own crayfish. It is recommended to soak the crayfish in clear water for two to three hours, then scrub it and cook it at high temperature before eating.
Suggestion 2: Because the protein content of crayfish is high, and protein will do great harm to human health after decay, it is suggested that crayfish must be eaten at one time after it is cooked. However, don't eat too much crayfish, because eating too much protein can easily lead to indigestion.
Suggestion 3: Because it takes time to brush and cook crayfish, crayfish in most restaurants are prepared in advance. Before eating crayfish, it is best to look at the fried crayfish's body. If the tail is curled up, it means it was alive before entering the pot. If the tail is straight, it means the shrimp is dead before it is put into the pot. Remember, dead crayfish cannot be eaten.