"teach people to fish", so that Xizang farmers can quickly increase their income.

The Spring Festival holiday is drawing to a close. Wang Chenghui, a professor at Shanghai Ocean University who just returned from Xizang a year ago, has already flown back to the artificial breeding ground of Yadong salmon in Xizang's Yadong County, 3000 kilometers away. More than 23 million fertilized eggs of Yadong salmon is his biggest concern.

"if the survival rate of this batch of salmon fry is more than half, that would be equivalent to more than 10 million fish fry. In this way, Xizang's local farmers will certainly be able to increase their income and become rich this year. " For this reason, this Spring Festival, Wang Chenghui is busier than usual. Every day, we have to make video calls with the staff of the breeding base, observe the situation of salmon fertilized eggs in real time, and sometimes "remote control".

Solving the problem of large-scale artificial breeding of Yadong salmon is not only a challenging subject for Wang Chenghui, but also a precise poverty alleviation project that can benefit the local people: it is expected that in March this year, these salmon fertilized eggs will hatch at the breeding base. After cultivation, adult fish production is expected to be more than 10,000 tons, which will occupy about 30% of the national salmon market, thus completely breaking the salmon market pattern.

The crab breeding expert took over the artificial breeding of Yadong salmon.

Wang Chenghui is a good crab breeder at Shanghai Ocean University. As the chief expert in the industrial technology system of Eriocheir sinensis in Shanghai, he has selected and bred a new national aquatic product, "Jianghai 21".

Why does this good crab farmer study Yadong salmon breeding across the border? It turned out that in April 2015, a precise poverty alleviation project fell on his shoulders. At that time, the person in charge of Xizang Yadong County visited Shanghai Ocean University, hoping that Shanghai Ocean University would deploy its strength to help local farmers solve the problem of large-scale artificial breeding of Yadong salmon.

"the market price of a jin of Yadong salmon is about 250 yuan. If Yadong salmon can be industrialized in Xizang, it should be no problem for a farmer to increase his income by tens of thousands of yuan a year. In Xizang, this is not a small income. " Wang Chenghui told reporters that Yadong salmon is a second-class wild aquatic product protection animal in Xizang Autonomous region, living in waters at an altitude of 2700-3700 meters. In addition to its high altitude, it is also a unique plateau cold water fish in Yadong.

Before specializing in crab breeding, Wang Chenghui followed his tutor to raise fish for four years, which was "a bit of a background for cold-water fish breeding and germplasm development." It is reported that the Yadong salmon artificial breeding farm in Xizang Yadong County is Xizang's most modern fish breeding farm at present, and it is also the first large-scale aquaculture construction project in Shanghai to support the development of Xizang area.

"teach them to raise fish hand in hand, so that they can increase their income."

Wang Chenghui said that no one has dared to challenge the artificial breeding of Yadong salmon for many years. Yadong salmon is significantly different from common cold-water fish: the period of estrus is short, only 7 to 10 days a year; a female fish weighing 2000 grams has only about 3800 eggs on average, while the number of eggs laid by four common domestic fish, such as grass carp, is about 1 million.

In addition, the incubation period of Yadong salmon is long, and the incubation period of general cold-water fish is less than one month, while the incubation period of Yadong salmon is as long as 100-110 days, which is more than three times that of ordinary cold-water fish. After the Yadong salmon eggs emerge from the membrane, it will take 30 days before they can swim.

"High altitude", "ultra-low temperature", "very few fertilized eggs", "long incubation period" and "low survival rate of domestication" are all technical problems that Wang Chenghui has never encountered. However, there is a bigger problem in front of Wang Chenghui: there is a shortage of people and technical personnel.

"many local people raise yaks at home and have no experience of raising fish at all. We have a very important task, which is to teach them to raise fish hand in hand, so that they can increase their income. " A team of experts led by Wang Chenghui taught the basic skills of fish farming hand in hand. From how to catch fish, to how to inseminate fish, how to hatch eggs, how to cultivate seedlings, and then to pond patrol management. In Yadong, Wang Chenghui changed from an aquatic products expert to an "omnipotent butler".

The key technical problems are solved one after another, paving the way for the industrialization of Yadong salmon.

Seeing that the work of the Yadong salmon artificial breeding farm is gradually on track, Yadong County puts forward the hope that 10 million Yadong salmon fry should be bred in 2017.

Wang Chenghui calculated with his fingers, which means "to get 1500 kilograms of fertilized eggs in 10 days." He told reporters that the average spawning of an adult female is about 270 grams, so in order to achieve the set goal, 500-600 female eggs must be squeezed out every day. Coupled with the poor maturity of some parent fish, more than 800 females and 300 males are screened every day.

Before the Spring Festival this year, Wang Chenghui's team had been busy for a while. As the technical difficulties had not yet made a real breakthrough and the technical personnel were not in place at that time, professors and graduate students from the working group of Shanghai Ocean University had to squeeze fish eggs together and teach technical points at the same time to drive local technicians to follow. My hands are sore and I can't move my shoulders. In this way, a working group composed of two teachers and six graduate students led local farmers in Yadong to complete egg squeezing and insemination of more than 6000 females and more than 2000 males. In 10 days, they harvested 1647 kilograms of fertilized eggs!

Under the technical guidance of the working group experts led by Wang Chenghui, Xizang's local farmers in Yadong have initially mastered the key techniques of parent fish cultivation, ripening and production promotion, artificial insemination, temperature control and hatching of Yadong salmon.

It is understood that according to the model of the first breeding farm, Xizang Yadong has successively invested in the construction of three commercial fish farms, all of which have paved the way for the industrialization of Yadong salmon.