This is a breeding colony of small-headed naked-rifts photographed under natural conditions at the source of the Yangtze River using an underwater camera.
The key fish species living at an altitude of about 4800 meters at the source of the Yangtze River, the small-headed nudibranch, have grown well after artificial insemination and hatching. This marks the first time that Chinese researchers have realized the large-scale artificial reproduction of key fish species with the highest distribution at sea level in the world.
The large-scale artificial breeding experiment of small-headed naked cracked Jiri was organized and carried out by the Yangtze River Academy of Sciences under the Yangtze River Water Conservancy Commission, and implemented with the cooperation of the Qinghai Fishery Technology Extension Center. Small-headed nudibranch is a large and medium-sized fish unique to China, a key protected fish in Qinghai Province, a key fish species in the Yangtze River source water ecosystem, and has high directional value for the study of the Yangtze River source water ecosystem and aquatic biological protection.
In Zhiduo County, Yushu Tibetan Autonomous Prefecture, Qinghai Province, Li Wei, a senior engineer at the Yangtze River Academy of Sciences, collected fish samples in Keyouqu. (Photo by Xinhua news agency reporter Wu Gang)
The reporter saw in the fry breeding pond of the Fishery Technology Extension Center of Qinghai Province that the juvenile fry that have been artificially bred on a large scale have been cultivated for more than 1 month, and the length of the fish is 2-3 cm. After water temperature regulation and bait configuration, the juvenile fish are currently swimming lively and growing well. According to reports, the small-headed naked rift is a cold-water fish, slow growth and development, growing to 50 cm long adult fish, generally take more than 10 years.
Li Wei, the leader of this experiment and a senior engineer of the Institute of Water Environment of the Yangtze River Academy of Sciences, introduced that there are currently 6 known fish species in the Yangtze River source. Among them, the small-headed nude jiri is large, and the adult fish feed on other fish such as plateau loach in winter, which is at the top of the food chain and is a key fish species at the source of the Yangtze River. As the key fish species with the highest known altitude distribution in the world, the small-headed nudibranch has obvious "three high" characteristics: the highest degree of evolution with the uplift of the Qinghai-Tibet Plateau, the high altitude distribution, and the high temperature difference between day and night in life history.
Li Wei inspects fertilized eggs of key fish in hatching from the Yangtze River source (photo taken on June 23).
The scientific expedition found that the small-headed naked-split-ruturded fish that has long survived on the Qinghai-Tibet Plateau has adapted to the living environment of high altitude, high cold and low temperature through continuous evolution. For example, the number of tentacles is reduced, the number of hypopharyngeal teeth is reduced, and the scales are reduced, so as to reduce carnivorous predation, scrape raw algae for food, adapt to the lack of plateau food and other environmental characteristics.
"In the case of 'continuous bottom freezing' in the winter river ice at the source of the Yangtze River, how the small-headed naked-cracked Jiri fish survive the winter and how to reproduce has been an unsolved mystery for a long time." Li Wei introduced that in the previous jiangyuan scientific expeditions, they explored the wintering grounds and spawning grounds of the small-headed nudibranchs in many ways, and studied and mastered the characteristics of the water temperature of the fertilized eggs of the small-headed nudibranchs.
On August 8, 2019, Li Wei observed fish samples collected in the source area of the Yangtze River. (Photo by Xinhua news agency reporter Wu Gang)
In June this year, the research team used the mature broodstock collected in The Yangtze River Nanyuan to obtain fertilized eggs through artificial insemination, and implemented artificial incubation at the Jiangyuan Base of the Yangtze River Academy of Sciences of the Ministry of Water Resources at an altitude of more than 4,000 meters, successfully achieving large-scale artificial reproduction. Subsequently, 20,000 newborn fry were transported by car across thousands of miles from Zaduo County, Yushu Tibetan Autonomous Prefecture, Qinghai Province, to Xining City, and were cultivated and observed in the cold-water fish breeding workshop of the Qinghai Fishery Technology Extension Center.
Wang Zhenji, senior engineer of the Fishery Technology Extension Center of Qinghai Province, said that the large-scale artificial breeding of small-headed naked-headed Sturgeon has achieved large-scale artificial breeding for the first time, which will accumulate valuable experience for the research and protection of other endemic fish in the Yangtze River source, as well as the subsequent artificial breeding and stocking.
Xu Ping, deputy chief engineer of the Yangtze River Academy of Sciences, introduced that the large-scale artificial reproduction of small-headed naked cracked jiri fish helps researchers systematically grasp the water temperature and salinity conditions required for spawning, hatching, growth and development of key fish species in the source of the Yangtze River, and lays the foundation for the subsequent artificial conservation of key fish at the source of the Yangtze River. The scientific research team will gradually extend the results of this artificial breeding experiment to the protection and breeding of other endemic fish in the Yangtze River source, and consolidate the basic research on the conservation of aquatic biodiversity in the Yangtze River source.
Source: Xinhua Viewpoint