Culture techniques of soft-shell lobster

One of the main reasons why lobster has not been regarded as a fishery resource in our country before is that its edible part is too low. In order to increase the edible part of lobster and improve its utilization rate, in the early 1990s, some countries in Europe and the United States made use of the phenomenon of molting in the growth process to study and produce soft-shell lobster, which was successful and carried out large-scale production. Therefore, one of the ways of development and utilization of lobster in China is the production of soft-shell lobster.

The advantages of soft-shell lobster

1. The edible part is improved.

By adopting the production technology of soft-shell lobster, the edible part of lobster can be increased to more than 90%. Preliminary experiments show that the average shell shed by the lobster accounts for 54.5% of the original body weight, but the soft-shell lobster has no weightlessness, and the weight loss rate is only 0.08%, which is negligible because the lobster absorbs a lot of water during the molting process. the molted shell is chitin and calcium carbonate which are difficult for human beings to digest and absorb. On average, the calcareous stone in the stomach accounts for only 0.93% of the body weight of the soft-shell shrimp, and the stomach and intestines of the shrimp will not exceed 2% of the body weight of the soft-shell shrimp. Therefore, the edible part of the soft-shell lobster can be increased to more than 90%.

2. Expand the range of food.

Molted soft-shell lobster can eat the whole soft-shell lobster as long as the two calcium stones in the stomach are removed to prevent the teeth from being damaged during eating, and the processing is simple and the taste is more delicious. At the same time, because the lobster completely exfoliates the shell of the whole body, including all appendages, gills and stomach, the soft-shell shrimp with exuviated shell is very clean, hygienic and beautiful.

3. Shrimp yellow can be used.

Because the soft-shell lobster can be eaten as a whole, the nutritious shrimp yellow has been fully utilized.

The production mode of soft-shell lobster

China is rich in lobster resources, but there is a big gap between China and foreign countries in the development and utilization of this resource. The United States produces and consumes the largest number of lobsters in the world. It has formed a very mature technology in the production of soft-shell lobster, including the design and construction of industrial production facilities and equipment of soft-shell lobster, and the use of biotechnology to control the molting speed of lobster. The biological characteristics of lobster combined with processing technology are used to prevent and delay the hardening of soft-shell lobster, so that a batch of soft-shell lobster can be put on the market. Louisiana is the only state in the United States. The annual production of soft-shell lobster is more than 45 tons.

1. Make use of the natural law of molting during the growth of lobster.

The molting of soft-shell lobster is a natural phenomenon in the life activities of all crustaceans. After natural hatching, with the development, metamorphosis and growth of the individual, the body can grow up again and again. Or complete a life activity, such as mating, spawning and reproduction. The molting of crustaceans has a certain rhythm, which is related to the species, growth stage, growing season, water temperature, nutritional status and environmental conditions of crustaceans. The lobster has to molt 11 times from hatching to larval shrimp, and the young shrimp can achieve sexual maturity only after many times of molting. The molting times of sexually mature female and male shrimp decrease rapidly, and the old shrimp basically molt once a year. Therefore, with the growth and growth of lobster, the number of molting decreases, and the interval between two molts is lengthened. The young shrimp usually molted once in 4-6 days, and once in 8-10 days when the young shrimp reached sexual maturity. The molting period of lobster is from April to October every year, but the peak period is from May to June. The lobster has the habit of hibernating. After several months of hibernation, the body consumes a lot of energy and the carapace grows thicker. In spring, the lobster climbs out of the cave and begins to eat a lot. At the same time, in order to grow rapidly, the carapace must be shed. The breeding period of lobster is from September to October, and the molting decreases obviously. There are precursors before the lobster molting, such as stopping eating before molting, reducing activity, and being quiet. The whole molting cycle can be divided into five stages: soft shell stage, late molting stage, intermolting stage, early molting stage and molting stage. As long as we master the molting law of lobster and design a living environment suitable for its growth and molting, we can carry out large-scale artificial production of soft-shell lobster. Louisiana has made use of its natural molting law to produce a large number of soft-shell lobsters.

2. Remove the X organ

Accelerate the lobster shell. Synchronous crustaceans that promote molting are regulated and controlled by hormones in the body. Modern studies have proved that there are two kinds of organs in crustaceans to control molting, namely X-organ and Y-organ. The x organ located in the eye stalk secretes and can store and release a molting inhibitory hormone; the Y organ located in the second mandible secretes and releases molt hormone, but its release is regulated by x organ secretion and inhibition of molt hormone. Therefore, the artificial removal of x organs can accelerate the molting of lobster and promote the synchronization of molting. This has been applied in the artificial production of prawns, sea crabs, river crabs and other shrimp and crabs, and achieved remarkable results.

3. Use molting hormone

Synchronous crustaceans that accelerate lobster molting and promote colony molting the molting of crustaceans is regulated by hormones, which have been clearly studied. The molting hormone of shrimp can be divided into twenty molting hormone and p-molting hormone, which are steroid hormones. Twenty molting hormone is the intermediate substance in the process of crustacean hormone formation, and it can be transformed into p-molting hormone. The molting cycle of shrimp is mainly controlled by the amount of 8-molting hormone 20-Hyudroxyecdysone,20-HE, that is, 20-hydroxyecdysone. It is known that there are analogues of shrimp molting hormone activity in more than 100 kinds of plants, which can be extracted manually. Several domestic manufacturers have produced "molting growth-promoting factor" for shrimp and crabs. Adding 0.1%-0.15% molting hormone to the feed can speed up the molting cycle and enhance the synchronization of population molting. At present, many units in China have used this hormone in the molting process of shrimp and crab larvae, and remarkable results have been achieved.

Production technology of soft-shell lobster

Lobster farms can use the following techniques to produce soft-shell lobsters:

1. Release seedlings with the same specifications during stocking.

At present, the seedlings of farmers are basically collected by the market or caught in the wild, and the specifications often vary greatly. When producing soft-shell lobster in breeding farms, species must be selected and seedlings with the same development and similar specifications must be put together, otherwise it is difficult to produce soft-shell lobster industrially.

2. Use shrimp molt growth-promoting factor

According to the size of the stocked seedlings, shrimp molting growth-promoting factor is added to the feed from 1 to 3 weeks after stocking, and the general dosage is 0.1%-0.15% of the feed. It is used to speed up the molting cycle of lobster and ensure the synchronization of population molting.

3. Build a suitable growth environment

The production of soft-shell lobster in farms must keep the culture environment consistent and relatively stable. In particular, the temperature of different places in the same stocking place should not be too different. The distribution of aquatic plants in the same stocking place is as uniform as possible, and the feeding is as reasonable as possible to make the lobster grow and develop under the same conditions.

4. Determine the fishing time

About 10 days before fishing, the growth and development of lobster was observed every 1-2 days to determine the last molting time before listing. And use this to determine when to fish.

Processing of soft-shell lobster

1. Processing of soft-shell lobster

After the lobster molts, the whole body tends to be clean, as long as a little processing can be eaten. Before eating, for the sake of safety, insert ophthalmic tweezers from the lobster's mouth or behind the eyes, take out the two calcites in the shrimp's stomach and stomach together, and pull the shrimp's intestines out of the shrimp's anus with tweezers, so that the whole soft-shell shrimp is clean and free of any dirt. In fact, the digestive system of the lobster is relatively simple. It is a straight tube from the mouthparts to the anus, which expands only in the stomach. In addition, the lobster stops eating for a few days before molting, and there is no content in the stomach and intestines after molting. In particular, the hard shell of the stomach is also exuviated when molting, so that the soft-shell lobster can be eaten after cooking without any processing, but pay attention to the calcium in the shrimp stomach and spit it out when eating. Prevent teething. The cooking method can be braised, or fried in oil for 1 minute or 2 minutes, then mixed with seasoning to eat, or processed into bread shrimp, long-term frozen preservation, take as you like. For the sake of safety and hygiene, it is recommended that soft-shell lobster not be eaten raw.

2. Preservation and preservation of soft-shell lobster

Most of the lobster is alive after molting, and if no measures are taken, the soft-shell lobster will soon harden. Through the experiment, it was found that the shell of the soft-shell lobster had partially hardened after 12 hours at the water temperature of 30 ℃. After two days, most of the body hardened, but it was not as hard as before molting, but at this time, the taste of the shrimp was poor, the shell could not be chewed, and lost the flavor and characteristics of the soft-shell shrimp. Although the hardening of soft-shell shrimp is carried out at the same time, the time of hardening is different in the body and the order of hardening is different. In the first step, the attack, defense and feeding organs such as the claw foot, other appendages and forehead are completely hardened, followed by the hardening of the abdominal carapace, and finally the complete hardening of the head and chest armour. In order to maintain the flavor of soft-shell lobster, soft-shell lobster must be treated fresh. The easiest way is to collect the lobster immediately after molting and store it in an environment below 18 ℃. If you want to keep it fresh, you can temporarily raise the freshly molted soft-shell lobster in water below 10 ℃, so that the shell will not harden and the soft-shell shrimp will not die for a week. If the shrimp is temporarily reared in 10-13 ℃ water, the soft-shell shrimp will not die after 35 days, but the shrimp shell has slightly hardened.