Old Version

Up the Creek

The extinction of aquatic species in China’s longest river, the Yangtze, demonstrates the continuous deterioration of their habitats. Much more needs to be done, say prominent conservationists

By Wang Yan , Zhang Xinyu Updated Jan.1

On July 21, 2022, the International Union for Conservation of Nature (IUCN) formally declared the Chinese paddlefish (Psephurus gladius) extinct, a species closely related to sturgeons that had been in existence since the Cretaceous period, an era when dinosaurs roamed the planet over 150 million years ago.  

In January 2020, Wei Qiwei, a researcher at the Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, and his team published an article in international journal Science of the Total Environment that predicted the extinction of Chinese paddlefish based on field surveys and miscatch records of when fishers accidentally haul in prohibited species as bycatch and alert conservation staff. The only Chinese member of the IUCN’s Sturgeon Specialist Group, Wei has been involved in the protection of Chinese paddlefish since 1984. 

“There’s something to be said about humanity, when a species that’s outlived the dinosaurs is pushed to the brink of extinction by humans who have, in comparison, existed for a mere blip in time,” said Beate Striebel-Greiter, an expert and leading member of the Global Sturgeon Initiative with the World Wide Fund for Nature (WWF), in a statement on July 21. “The world’s failure to protect sturgeon species is an indictment of governments around the world for failing to sustainably manage their rivers and meet their commitments to conserve these iconic fish and halt the global loss of nature,” Arne Ludwig, Chair of the IUCN Sturgeon Specialist Group, said in the same statement.  

“In the Yangtze River, the Chinese paddlefish is not the only extinct or endangered species. Many species disappeared silently before people realized it was happening,” Wei said. “The extinction of the Chinese paddlefish reminds us again that rare aquatic animals in the Yangtze River have fallen into a dilemma between life and death, while humanity still has much to do.” 

Last Sighting 
The paddlefish did not just become extinct. Wei’s team estimated it was functionally extinct by around 1993, when its natural populations were unable to reproduce. He thinks the actual extinction may have occurred between 2005 and 2010. This means the Chinese paddlefish was already gone for over a decade before people realized it.  

There was scant research on the habits, characteristics and breeding of the Chinese paddlefish. Wei said there were few papers, with only around 40 containing biological data. Because they were so rare, not many biologists studied them.  

The Chinese paddlefish was recorded in ancient Chinese books such as The Book of Songs, the earliest Chinese poem collection compiled around 500 BCE, when sturgeon species were still widely distributed in China. According to one poem, ancient people sacrificed them to their ancestors. Until the 1970s, sightings of Chinese paddlefish were common in the Yangtze River, where fishers would catch 25 tons annually. He Shunping, a researcher at the Institute of Hydrobiology, Chinese Academy of Sciences, grew up in Luzhou, Sichuan Province. He told NewsChina that he remembers seeing fishers carrying large Chinese paddlefish of over one meter long beside the Yangtze River. But since the 1980s, sightings of Chinese paddlefish were rare. He has only seen an adult paddlefish as a deceased specimen in a lab.  

In 1989, the Chinese paddlefish was listed as a national top-level protected species. Other than scientists like Wei Qiwei and fishers before the 1980s, very few people know what kind of creature it is.  

“The Chinese paddlefish is a marvelous creature with a unique elongated sword-like snout [rostrum], and beside the snout and gills are plum blossomshaped spots to attract prey like small fish, crustaceans and insects,” Wei said. “When the prey approaches, the paddlefish can sense it from afar. It may not be able to swim for a long time when hunting, so it tries to hide in a place to wait until the fish swims over, when it will suddenly catch the prey in its mouth.”  

The large rostrum is believed to be an adaptation to improve its sense of electroreception. Like a shark, the Chinese paddlefish possessed the ability to sense electrical fields produced by the muscles of its prey.  

The general weight of a Chinese paddlefish was around 200-300 kilograms. Bing Zhi (1886-1965), a Cornell-trained professor known as the founder of modern biology in China, recorded that fishers in Nanjing, Jiangsu Province had caught a Chinese paddlefish measuring seven meters long and weighing 907 kilograms.  

In the 1990s, researchers explored artificial breeding technology for Chinese paddlefish, and the US was also interested in cooperating with China. But it was too late. “There were too few left to catch. How could you conduct artificial breeding then?” Wei said. Artificial breeding technology should have been studied before the paddlefish went extinct, he said.  

Technical restrictions resulted in the failure of breeding wild paddlefish in captivity. A fierce aquatic animal, the Chinese paddlefish’s elongated snout accounts for one-third of its length. When researchers caught an adult paddlefish and put it in a pool, it had a strong stress reaction and would hit its snout on the edge, which could kill the fish. “Even if it survived that, the Chinese paddlefish may still starve itself to death [in captivity],” Wei said.  

The last confirmed sighting of a Chinese paddlefish was in 2003 when an adult was caught by accident in Yibin, Hubei Province. Mu Tianrong, former director of Yibin Fishery Bureau remembers his encounter with the elusive fish. At 2:30pm on January 24, 2003, he received a phone call from a fishery administration station, saying that a fisher had mistakenly caught a Chinese paddlefish. Mu immediately set off in a speedboat with the head of Yibin City Cuiping District fishery administration station. “I was shocked to see a giant Chinese paddlefish probably over 3 meters long and as big as a cow,” Mu said. He immediately reported the situation to city and provincial leaders and contacted experts, including Wei Qiwei. After four days of rescue and treatment, the Chinese paddlefish was strong enough for release. Wei said they released the paddlefish for two reasons. First, artificial breeding was not ready and previous attempts had failed. Second, the consensus among experts was that they could tag it and follow its movements, find its companions and its spawning grounds to facilitate future study.  

But they lost the signal two days after release. The Yangtze River Fisheries Research Institute organized 17 searches at different locations to find it until May 21, 2003, but the paddlefish was never spotted again. It was the last of the species seen alive.  

Wei said that with approval from the former Ministry of Agriculture and support from the Three Gorges scientific research project team, he continued to lead a search for the paddlefish for eight years. “We monitored habitats and mobilized local people, especially fishers along the river, to report any large fish that were found, either dead or alive,” Mu said.  

After Wei Qiwei’s team predicted the extinction of Chinese paddlefish through computer modeling in 2019, people realized the 2003 encounter was really the last. Now, with no surviving domesticated individuals, people can only see the animal through photo archives or preserved specimens. 

Fragile Environment 
Scientists have discussed for years why the paddlefish went extinct. He Shunping told NewsChina that the paddlefish is an ancient species. Although it lived until now, it had poor adaptability. “The Yangtze River is a fragile environment for large fish. The larger the fish is, the smaller the population, since the larger fish will eat much more food than the smaller fish, and they need a wider habitat to survive,” he said. He believes human activities were the last straw for the Chinese paddlefish.  

Human activities such as overfishing, mechanical damage, noise pollution caused by water traffic, water pollution and other factors led to the reduction of the paddlefish population. However, according to Wei, the main reason is dam construction, which blocked the channel between the creature’s spawning grounds and its food sources. 
The first large dam to block the main channel of the Yangtze was the Gezhouba Dam, built in 1981 at Yichang, Hubei Province. It split the river in two, but the builders did not include a fish ladder to help fish whose spawning grounds were upstream.  

“Gezhouba Dam’s hydropower facilities had a great impact. Furthermore, the ships there are also relatively big. Largescale sand and gravel excavation disturbs the river bed, and excessive artificial light at night at docks and urban areas may also affect the survival of fish,” Wei said.  

According to Wei’s study, paddlefish breeding was severely restricted after the Gezhouba Dam was completed, as normally they would swim several hundred kilometers upriver from the dam to spawn.  

“The paddlefish was a migratory fish and needed a large territory. They spent most of their lives in the lower reaches of the Yangtze River and at the estuary. They swam back against the current upstream to spawn in March and April,” Wei told newspaper Southern Weekend in July 2022. “The dam separated the Chinese paddlefish into two groups. The paddlefish downstream couldn’t go back up to the spawning grounds to reproduce naturally, and the breeding efficiency of the paddlefish above the dam decreased significantly [due to lack of sufficient food resources],” Wei said.  

In an interview with WeChat account BooksAndFun, Wei said that large dam projects such as Gezhouba and the Three Gorges Dam (completed in 2006) affected the overall hydrological rhythm of the Yangtze River. The biggest reservoir in the world, the storage capacity of the 2,335-meter long reservoir changes the hydrology, water temperature and rhythm (seasonal regularity) of the Yangtze River, which suppresses the gonadal development of the paddlefish and physical conditions related to spawning.  

In December 2019, China’s Ministry of Agriculture and Rural Affairs announced a complete fishing ban in 332 nature reserves and aquatic germplasm reserves from January 1, 2020. Authorities imposed a 10-year fishing ban in the main channel and major tributaries of the Yangtze River from January 1, 2021.  

Wei suggested that no more hydro projects should be built and existing hydro projects should pay compensation to rehabilitate fish habitats. 

More than 600 Chinese sturgeons of different ages and species are released into the Yangtze River during an event to raise public awareness about river protection, Yichang, Hubei Province, May 14, 2022 (Photo by VCG)

Irreversible Damage 
Other than the Chinese paddlefish, the survival of many rare aquatic animals, in particular the sturgeon species in the Yangtze River, also hangs in the balance.  

From 2017 to 2019, the Ministry of Agriculture and Rural Affairs launched the Yangtze River Fishery Resources and Environment Survey Project. According to the report, over 130 of the 448 species of fish recorded in the Yangtze River were not spotted during the survey, accounting for nearly one-third of the total number of fish distributed in the Yangtze River. “It might be that some of the fish that were not found are already rare, but other species like the Chinese paddlefish may be already extinct,” Wei said.  

According to the IUCN announcement in July, 100 percent of the world’s remaining 26 sturgeon species are at risk of extinction, up from 85 percent in 2009.  

Among them, the Chinese sturgeon (Acipenser sinensis), another important species in the Yangtze River, is listed as “critically endangered” by the IUCN Red List of Threatened Species and the Yangtze sturgeon was moved from Critically Endangered to Extinct in the Wild.  

The Chinese sturgeon conservation reserve, covering an area of 6,736 hectares, was established in 1996 in Yichang, Hubei Province in the middle reaches of the Yangtze.  

The reserve is designated to protect the natural breeding area of the Chinese sturgeon, their habitats and spawning ground. It also provides a natural habitat for other rare aquatic species such as the Yangtze sturgeon and Yangtze finless porpoise, as well as for four commercially important fish species including herring, grass carp, silver carp and bighead carp. The conservation area plays a key role in preserving the Chinese sturgeon, since it includes the fish’s only spawning ground in the country.  

Artificial breeding and release are important ways to protect the Chinese sturgeon. Juvenile, subadult and adult Chinese sturgeon are released into the Yangtze River to restore or revive the natural population of the species.  

A widely cited figure is that China has released over 7 million captive-bred Chinese sturgeon in the past 40 years, and over 3 million Chinese sturgeon have been released in Yichang during this time. However, despite the continuous artificial proliferation and release, the natural population of Chinese sturgeon has declined. Wei believes this is because the number of released fish is too low.  

“It’s completely different when you release aquatic animals compared with returning terrestrial animals to the wild. It would be a significant number if scientists released 10 tigers to the wild, but the natural fatality of fish is high, so releasing 100,000 fish in tributary rivers may only result in 5 percent surviving by the time they arrive at the Yangtze Estuary,” Wei said.  

Artificial breeding of the Chinese sturgeon has been difficult. Private enterprises that breed sturgeon for repopulation and conservation cannot attract enough government support. In 2018, more than 6,000 artificially bred Chinese sturgeon died after local government-led construction projects disturbed breeding ponds owned by Hubei Hengsheng Industrial Company, the country’s first private Chinese sturgeon breeder. 
The company was forced to relocate its breeding center. According to Wei, many other private enterprises retreated from this field over the years as they could not afford the high costs involved in breeding the Chinese sturgeon.  

Addressing the rapid decline of the wild Chinese sturgeon, and in order to protect it, the Ministry of Agriculture and Rural Affairs compiled the Chinese Sturgeon Rescue Action Plan (2015-2030), its first single-species protection plan. However, Wei said that although it has been implemented for several years, the action plan has not been well promoted, and the main actions such as large-scale breeding base construction, spawning ground restoration and genetic diversity preservation have not been effectively implemented, and there is still no special funding for artificial breeding and release programs.  

Wei called for immediate action to protect rare aquatic animals in the Yangtze River. He said the 10-year Yangtze fishing ban will give fish species time to recover.  

“Before implementing the policy, fish could be caught as soon as they were released. We started releasing Yangtze sturgeon around 2007, and statistics revealed fishers caught almost all of them within three months.”  

In He Shunping’s view, besides the ban, small hydropower stations should be dismantled to restore the natural flow of the river. Some small hydro projects along the Chishui River, an upstream tributary of the Yangtze, have been dismantled in recent years.  

“If more places take action, it will have a relatively big impact,” He said. “As the extinction of rare aquatic animals in the Yangtze River is accelerating, humans should speed up the race against these extinctions.”  

Although scientists have not seen the paddlefish for years, their rescue efforts never cease. In 2014, Wei Qiwei’s team introduced the most advanced endangered fish preservation technology from abroad and started surrogate pregnancy research among fish species to arm themselves with technical preparation for the rescue of the Chinese paddlefish.  

“Extinction is a scientific conclusion, but we always hope that there might be an exception. If so, and someday we spot a Chinese paddlefish, could we use the technology to revive the species? At least we could adopt these technologies to help other endangered species,” Wei said.  

He Shunping told NewsChina that he will attempt to genome sequence the Chinese paddlefish by taking tissue from dead specimens. But this is challenging since they were usually preserved using chemicals like arsenic, destroying its DNA. But scholars are still trying.  

Wei told the reporter that if the State had ordered breeding efforts earlier, perhaps the giant fish would not be extinct.  

“Just look at the Chinese sturgeon and the Yangtze sturgeon. Now we have artificially bred individuals, so at least this species can survive,” he said.