In the Yangtze River basin, there are more than 400 species of fish, of which 96 species are under key protection, and the Chinese sturgeon and the Yangtze sturgeon are among the flagship and iconic species. The ancients once wrote the poem "Eyes are like pearls and scales are like gold" to describe the sturgeon, the oldest vertebrate animal on earth. The Chinese sturgeon has not been monitored for seven years now, and the Yangtze sturgeon has ceased natural reproduction since 2000. Since the total ban on fishing, the fish resources and biodiversity of the Yangtze River have shown a trend of recovery, but can the wild populations of iconic species such as the Chinese sturgeon and the Yangtze sturgeon recover?
Chinese sturgeon and Yangtze sturgeon are different in rare creatures
Although both were born in the Yangtze River, the Chinese sturgeon and the Yangtze sturgeon live in different areas. The Yangtze sturgeon is a freshwater sedentary fish, distributed in the lower reaches of the Jinsha River and the upper reaches of the Yangtze River, although it is a migratory fish, but does not migrate for a long distance, while the Chinese sturgeon lives in the Yangtze River and coastal waters, and belongs to the long-distance migratory fish of the Haihe River. During the breeding season, mature Chinese sturgeons travel up the Yangtze River estuary from July to August and travel all the way from October to November to their spawning grounds in the upper reaches of the Yangtze River to breed. After breeding, the hatched baby Chinese sturgeon will follow the migratory route down the Yangtze River to the mouth of the Yangtze River, and enter the sea from April to May of the following year.
In terms of body shape, there are also differences between the two types of fish, the Yangtze sturgeon is smaller, with an adult sturgeon measuring 1-1.5 meters long, and the Chinese sturgeon is larger, with an adult Chinese sturgeon reaching a length of 4 meters.
Drinking the same water from the Yangtze River, the Chinese sturgeon and the Yangtze sturgeon have very different personalities. The Yangtze sturgeon likes to be quiet and swims slowly. The Chinese sturgeon, on the other hand, likes to swim around against the walls and bottom.
Chinese sturgeon: a "living fossil" in aquatic life
The Chinese sturgeon is a first-class key protected wild animal in China and is known as a "living fossil" among aquatic organisms. In the early 70s of the 20th century, the Yangtze River caught an average of more than 580 Chinese sturgeons per year. In 1983, the mainland banned the commercial fishing of Chinese sturgeons, and since then the Chinese sturgeon has been restocked, but it has not been able to stop the rapid decline of its population. Since 2017, only a dozen Chinese sturgeons have been monitored in the Yangtze River each year.
Yangtze sturgeon: Natural breeding in the wild ceased more than 20 years ago
The Yangtze sturgeon, a national first-class protected animal, stopped reproducing naturally in the wild around 2000, and in July 2022, the International Union for Conservation of Nature declared the Yangtze sturgeon extinct in the wild.
At present, the mainland is continuously strengthening the artificial breeding and restocking of Chinese sturgeon and Yangtze sturgeon.
Can Yangtze sturgeons spawn and reproduce naturally in spawning grounds?
The Yibin Jiang'an section of the Yangtze River has always been the traditional habitat and spawning ground of the Yangtze sturgeon. The transformation of artificially constructed natural water spawning grounds has been carried out here, and in 2024, new trials will begin. Recently, the Yangtze sturgeon, which was artificially released for the first time in mainland China, spawned and reproduced naturally in the transformed spawning grounds, providing important theoretical and technical support for the restoration of the Yangtze sturgeon's habitat in situ.
In 2023, researchers put 20 male and female adult Yangtze sturgeons into artificial ovaries in the Jiang'an section of the Yangtze River in Yibin, Yangtze River, to guide the Yangtze sturgeon to lay eggs and mate for fertilization.
This year, researchers removed the artificial ovaries and switched to fishing nets to enclose them, planned a natural water test site, and built an artificial spawning ground.
On March 22, researchers introduced 62 captive-bred Yangtze sturgeons, and nearly a week later, no breeding behavior was found.
Researchers adjusted the plan and repurposed the spawning grounds with pebbles. Due to the rise in water temperature, the water pump was used to continuously introduce water from the main stream of the Yangtze River to cool down the test site.
On March 31, researchers finally observed that the Yangtze sturgeon had reproductive behaviors such as free gathering, chasing, fast tail wagging, and jumping in the spawning grounds.
On the morning of April 6, the underwater camera also successfully recorded the natural breeding behavior of the Yangtze sturgeon.
The reporter visited the artificial spawning grounds of the Yangtze River sturgeon underwater
The reporter of the main station went underwater to visit the artificial spawning grounds of the Yangtze sturgeon.
Reporter Bai Lu: I can see that this stone is very smooth, this is our artificial layout of the birth bed, because the natural river stone has a lot of algae, it is not conducive to the attachment of fish eggs, so this is why we need to transform the spawning bed, there is a wire paving at the bottom of the stone on top, this is really like a birth bed for fish parents and fish mothers. There was a Yangtze sturgeon in front of us, and it was very close to us, and we were actually floating above it.
Two generations have one responsibility
Guarding the light of artificially reproduced life
In fact, today's artificial breeding is also thanks to the protection of more than a dozen wild Yangtze sturgeons by scientific researchers. There are 19 wild Yangtze sturgeon parents recorded in the mainland, of which 18 are in the Sichuan Yibin Institute of Rare Aquatic Animals, and most of the artificial breeding of the Yangtze River sturgeon in China are the descendants of these 18 Yangtze sturgeons. Zhou Liang has been caring for these wild Yangtze sturgeons for nearly 30 years.
In 1993, Zhou Liang, who had just graduated from university, assisted his father in establishing the Yibin Institute of Rare Aquatic Animals. The father and son bought the injured Yangtze sturgeon from fishermen and protected them at the farm. Yibin is located at the junction of Sichuan, Yunnan and Guizhou provinces, where the Jinsha River, the Min River and the Yangtze River meet, and has historically been the breeding habitat of many rare fish such as the Chinese sturgeon and the Yangtze River sturgeon.
At its peak, the institute rescued more than 70 wild Yangtze sturgeons, and raised 50 juvenile Chinese sturgeons, as well as hundreds of rare and endemic fish such as cochineal. The more fish are raised, the cost is getting higher and higher, and when it is the hardest, only the father and son are left in the institute. They came up with the idea of artificial breeding.
In 1998, father and son successfully bred hundreds of Yangtze sturgeon fry for the first time.
Since 2007, Yibin has carried out activities to increase and release the Yangtze sturgeon, and so far, the institute has provided more than 500,000 Yangtze sturgeons for release.
In 2016, Zhou Shiwu passed away due to illness, and Zhou Liang took over the baton and cooperated with a number of units to continue to carry out the Yangtze River sturgeon population reconstruction pilot project.
Zhou Liang, director of the Yibin Institute of Rare Aquatic Animals: They are the masters of the Yangtze River, and without these species, there would be no rich diversity of this creature. We can do our part for this, and I feel like I didn't come to this world in vain.
Source: CCTV News