My Deep-sea Fishery

Moreover, large yellow croaker is a warm and humid inshore migratory fish, which often inhabits the middle and lower layers with a water depth of less than 60 meters, and is extremely difficult to catch.

But compared with bluefin tuna, large yellow croaker is still far behind.

The most important thing is that large yellow croaker has been cultivated artificially.

Although the conditions of breeding are very harsh.

The culture pond will be a rectangular pond with an east-west direction, with an area of ​​more than 6 mu, and can maintain a water depth of more than 2.5 meters. The bottom of the pond is inclined to a certain slope towards the drain direction, and the bottom is sandy and muddy.

The breeding site should not only have convenient transportation, but also have a relatively quiet surrounding environment, rich fresh water resources, and convenient drainage.

Generally, a large yellow croaker breeding pond needs to be equipped with at least two 1.5 kW water wheel aerators and one 1.5 kW jet aerator.

And the surrounding environment of the breeding pond needs to comply with the relevant provisions of the "Environmental Standards for the Origin of Pollution-Free Aquatic Products", and the water quality of the aquaculture water must comply with the relevant provisions of the "Water Quality Standards for Fisheries" and "Water Quality of Pollution-free Food Freshwater Aquaculture".

But no matter how harsh the conditions are, human beings have a way to achieve them.

However, with the success of large yellow croaker farming technology over the years, the price of large yellow croaker has not dropped much.

Whether it is the large yellow croaker whose seed has been desalinated or the real seawater large yellow croaker, the price is extremely high.

In fact, the difficulty of breeding large yellow croakers is even greater than most people imagine.

It is said that the steps before raising large yellow croakers are extremely complicated. First, clear ponds must be disinfected.

Before the fish species are stocked, the entire pond should be drained, and the bottom of the pond should be exposed to the sun for a period of time to remove excess silt.

Fifteen days before stocking large yellow croaker fry, they should be thoroughly disinfected with quicklime. Clear ponds with water should be used, and 150 kg of quicklime per mu should be used to splash the whole pond.

Tea cakes, bleaching powder and other drugs can also be used to disinfect clear ponds.

The drugs used for disinfection in clear ponds should comply with the relevant provisions of the Guidelines for the Use of Drugs for Pollution-Free Food and Fisheries.

The domestication of feeding habits of large yellow croaker fry is even more important in breeding large yellow croaker.

First of all, the bait must be domesticated. The preferred bait is surimi processed from fresh low-value fish and coastal small fish and shrimps. It is mixed with eel feed to make compound feed for feeding, and then gradually increase the artificial bait and reduce the amount of surimi. Until the artificial compound feed is completely fed.

In the bait acclimation stage, workers need to place feed at a fixed point and time, and also need signal training for baiting, that is, sending a fixed signal before baiting, so that the fish form a conditioned reflex and make them get used to flocking to ask for food.

If the domestication is not successful for half a month, then these large yellow croakers will basically starve to death.

The desalination treatment of large yellow croaker is not simple, and many fry will die in the process.

The desalination treatment is to gradually add fresh water to the nursery pond to reduce the specific gravity of the pond water and adapt the seedlings to grow in fresh water.

The gradient change of salinity during desalination has a significant impact on the survival rate of large yellow croaker. The larger the gradient and the longer the desalination time, the lower the survival rate of large yellow croaker fry.

It generally takes 7 to 10 days to desalinate. When the salinity of the pond water reaches below 2‰, the seedlings can be put into the pond to grow. This process is not without effort.

And it's not over yet.

When the stocking seedlings are free from disease, injury, deformity and strong mobility, the stocking density should also be determined according to the pond conditions and technical level.

The bait used throughout the breeding process must be seawater fish compound feed, and farmers need to feed it twice a day.

Before feeding, it is necessary to send a fixed signal first, so that the fish school can form a conditioned reflex, so that they get used to grouping together and asking for food, feeding from less to more, and the "cuckoo" of the large yellow croaker can be heard from the water. When the sound grows from small to loud, it proves that the fish has entered the feeding ground and is eating vigorously, and the sound gradually disappears after the fish is full.

The daily feeding rate is 7-8% of the fish body weight in the early stage, and 3-5% of the fish body weight in the middle and late stages.

Feeding should be carried out in strict accordance with the "four determinations" principle, and the amount of bait should be adjusted appropriately according to the situation of residual bait, combined with weather, water temperature, water quality and fish activities.

In order to increase the survival rate of large yellow croakers, farmers also need to regularly add drugs such as aquatic multidimensional, astragalus polysaccharide, and three yellow powder to the bait to prevent the occurrence of diseases.

Moreover, the bait eaten by farmed large yellow croaker is not cheap, and the bait it eats should all comply with the relevant regulations of the "Safety Limits of Pollution-Free Food Fishing Compound Feed". The drugs used should comply with the relevant provisions of the "Guidelines for the Use of Pollution-Free Food and Fishing Drugs".

Water quality also directly affects the normal growth of large yellow croaker. Only by adjusting the water quality can it promote the normal growth of large yellow croaker, effectively prevent the occurrence of diseases, increase the production of aquaculture, and achieve the purpose of increasing production and income of aquaculture.

The water quality for feeding large yellow croakers must be fresh and not too fat.

In the initial stage of stocking fish species, the water level is about 70-80 cm. After that, fresh fresh water is added to the pool by 5-10 cm every 2 days, and the water is not changed until the highest water level is reached.

The water level in early spring and late autumn is relatively low, which is conducive to increasing the water temperature.

In summer and winter, the water level should be raised as much as possible.

The most important thing is that the water needs to be changed every 2 days. The amount of water change is 1/4 to 1/3 of the whole pool. It is very troublesome for ordinary people to even change the water.

When the water temperature is lower than 13°C, basically do not change the water.

When the water temperature is higher than 28°C, it is necessary to change the water every day, and the amount of water change should be about 1/3. During the high temperature season in summer, drain water in the afternoon and water in the evening, so as to stimulate the flow of water, improve the appetite of large yellow croakers, and shape the body of large yellow croakers. color.

All these difficulties have always led to the high price of large yellow croakers.

As for the wild large yellow croaker?

It has long been included in the IUCN Red List of Threatened Species.

Large yellow croaker was once an important economic fish species in my country's oceans, and was once listed as one of the four major marine fisheries together with small yellow croaker and hairtail cuttlefish in history.

In 1974, the output of large yellow croaker was as high as more than 200,000 tons. However, due to the development of the knocking fishery in the 1950s, the fishing of non-spawning broodstock in the 1960s and 1970s, the excessive use of wintering grounds and the fishing of juveniles, the resources of large yellow croaker have rapidly increased. In 2000, the output in the East China Sea was only 9,035 tons, while the Guanjing Ocean, Maotou Ocean, and Damu Ocean could not form a fishing season.

This is impossible, because the economic value of the large yellow croaker is too high.

The meat of large yellow croaker is fresh and tender, rich in protein, and it is a good product for fresh food. It is not only sold fresh, canned and processed into "melon croaker" and "yellow croaker", but also can be used comprehensively.

The swim bladder of large yellow croaker can be dried to make various valuable foods, such as "fish maw", and it can also be made into yellow croaker glue, which is the raw material of high-grade adhesives for industrial use.

Moreover, large yellow croaker has certain medicinal value and is the raw material of some traditional Chinese and western medicines.

The swim bladder of large yellow croaker can be made into traditional Chinese medicine, which has an immediate effect on the treatment of sinusitis.