Teaching them how to fish helps Tibetan fish farmers increase their income quickly

As the Spring Festival holiday draws to a close, Wang Chenghui, a professor at Shanghai Ocean University who had just returned to Shanghai from Tibet before the festival, has long since let his thoughts fly back to Yadong County in Tibet, 3000 kilometers away - to the Yadong trout artificial breeding farm, where more than 23 million fertilized eggs of Yadong trout are his greatest concern.

"If the survival rate of this batch of trout fry exceeds half, that would mean more than 10 million fry. That way, the local fish farmers in Tibet will definitely be able to increase their income and become better off this year." For this reason, Wang Chenghui was even busier than usual during this Spring Festival. Every day he had to have video calls with the employees at the breeding base and observe the condition of the trout fertilized eggs in real time, and sometimes there was no shortage of "remote direction."

For Wang Chenghui, solving the problem of large-scale artificial breeding of Yadong trout is not only a highly challenging research topic, but also a targeted poverty alleviation project that can benefit the local people: it is expected that in March this year, this batch of trout fertilized eggs will hatch and emerge from their membranes at the breeding base. After being raised to maturity, the adult fish output is expected to be more than 10,000 tons, which will account for about 30% of the national trout market, thereby completely breaking the market structure of trout.

A crab breeding expert took on the job of artificial breeding of Yadong trout

At Shanghai Ocean University, Wang Chenghui is an expert in crab seedling breeding. As the chief expert of the Shanghai Chinese mitten crab industrial technology system, he has already bred the Chinese mitten crab "Jianghai 21," a national-level new aquatic variety.

Why did this expert at raising crabs cross over to research the breeding of Yadong trout? It turned out that in April 2015, a targeted poverty alleviation project landed on his shoulders. At that time, the person in charge of Yadong County in Tibet visited Shanghai Ocean University, hoping that Shanghai Ocean University could assign personnel to help local fish farmers solve the problem of large-scale artificial breeding of Yadong trout.

"The market price of one jin of Yadong trout is about 250 yuan. If Yadong trout can be industrialized in Tibet, then it should be no problem for one fish farmer to increase their annual income by several tens of thousands of yuan. In Tibet, this is a considerable income." Wang Chenghui told reporters that Yadong trout is a second-class wild aquatic product protection animal of the Tibet Autonomous Region and lives in waters at an altitude of 2700-3700 meters. In addition to the high altitude, it is also a unique plateau cold-water fish species of Yadong.

Before specializing in crab seedling breeding, Wang Chenghui had followed his advisor and raised fish in ** for 4 years, "which counts as having some background in cold-water fish breeding and germplasm development." It is reported that the Yadong trout artificial breeding farm located in Yadong County, Tibet, is currently the most modernized fish breeding farm in Tibet, and is also the first large-scale aquatic product construction project in Shanghai's paired assistance to the development of the Tibet region.

"Teach them how to raise fish hand by hand, so that they can increase their income"

Wang Chenghui introduced that for many years no one had dared to take on the challenge of artificial breeding of Yadong trout. Yadong trout differs significantly from common cold-water fish: the estrus period is short, only 7 to 10 days a year; the egg-carrying capacity is low, and a 2000-gram female fish has on average only about 3800 eggs, while common four major Chinese carps such as grass carp have an egg-carrying capacity of about 1 million eggs.

In addition, the hatching period of Yadong trout is long. The hatching period of ordinary cold-water fish generally does not exceed one month, while the hatching period of Yadong trout is as long as 100-110 days, more than three times that of ordinary cold-water fish. After Yadong trout eggs emerge from their membranes, they still have to wait 30 days before they can swim.

"High altitude," "ultra-low temperature," "extremely few fertilized eggs," "extremely long hatching period," and "low survival rate in food training" - these are all technical problems Wang Chenghui had never encountered. However, there was an even bigger problem standing in front of Wang Chenghui: there was a shortage of people here, and technical personnel were severely lacking!

"Many local people raise yaks at home and have no experience raising fish at all. One very important task for us is to teach them how to raise fish hand by hand, so that they can increase their income." The expert team led by Wang Chenghui began teaching basic fish-raising skills hand by hand. From how to catch fish, to how to fertilize fish, hatch eggs, and cultivate fry, and then to pond patrol management... In Yadong, Wang Chenghui changed from an aquatic expert into an "all-around steward."

Key technical problems were solved one after another, paving the way for the industrialization of Yadong trout

Seeing that work at the Yadong trout artificial breeding farm was gradually getting on track and showing improvement, Yadong County expressed a hope: in 2017, it would be best to breed 10 million Yadong trout fry.

Wang Chenghui counted on his fingers, which meant that "within 10 days, 1500 kilograms of fertilized eggs must be obtained." He told reporters that an adult female fish produces on average about 270 grams of eggs, so to reach the set target, the eggs of 500-600 female fish had to be squeezed out every day. In addition, because some broodstock had poor maturity, more than 800 female fish and more than 300 male fish had to be screened every day.

Before this year's Spring Festival, Wang Chenghui's team had already been busy for quite a while. Because at that time a real breakthrough in the technical difficulties had not yet been achieved and technical personnel were not in place, the professors and graduate students of the Shanghai Ocean University working group had to join forces to squeeze fish eggs, while also explaining technical points and getting local technical personnel to follow along. Their hands became sore from squeezing, and their shoulders could not move... In this way, the working group consisting of 2 teachers and 6 graduate students led local fish farmers in Yadong to complete egg squeezing and fertilization for more than 6000 female fish and more than 2000 male fish. In 10 days, they harvested 1647 kilograms of fertilized eggs!

Under the technical guidance of experts from the working group led by Wang Chenghui, local fish farmers in Yadong, Tibet, have initially mastered key technologies for Yadong trout such as broodstock cultivation, ripening and spawning promotion, artificial fertilization, and temperature-controlled hatching.

It is understood that, following the model of the first breeding farm, Tibet's Yadong has now successively invested in the construction of three commercial fish farms, and these efforts have paved the way for the industrialization of Yadong trout.