One of the world’s largest freshwater fish species, the Chinese paddlefish, has been declared extinct by scientists.

According to Chutian Metropolis Daily on Jan. 3, the species (Psephurus gladius), one that is native to the Yangtze River and can grow up to seven metres long, was also known as the "king of freshwater fish" in China.

It is believed to one of the top ten largest freshwater fish in the world.

Believed to have disappeared between 2005 and 2010

This piece of bad news was announced by Chinese scientists who published a research paper in the leading international peer-reviewed scientific journal, Science of the Total Environment, last week.

The Chinese paddlefish was one of the two surviving members of a primitive fish group that was most diverse and widespread 34-75 million years ago.

There were 210 sightings of the paddlefish between 1981 and 2003.

The paddlefish was declared functionally extinct by 1993.

It is believed to have disappeared between 2005 and 2010, according to the research paper.

The last time a live Chinese paddlefish was spotted was in 2003 by a contributor to the research paper, a scientist named Wei Qiwei.

Wei told Hunan Daily that the paddlefish was accidentally caught by a fisherman back then and it was about four metres long, weighed about 300kg and was estimated to be around 30 years old.

Wei and his colleagues attended to some of the wounds on its head and tail, and added a tracker before releasing it back into the Yangtze river.

However, they eventually lost track of that paddlefish and that was the last time anyone sighted one.

Later on, a survey done between 2017 and 2018 found 332 fish species in the Yangtze basin but not one of them was the Chinese paddlefish.

In mid-September 2019, a panel of experts from the International Union for Conservation of Nature met in Shanghai.

They evaluated the status of the Chinese paddlefish and concluded that the species is extinct. 

Causes of extinction

The Chinese paddlefish used to be common in the Yangtze River until it was heavily harvested in the 1970s.

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The paddlefish was prized for its caviar and its huge size which could feed an entire village, according to Yale Environment 360.

Adding on to overfishing, the research paper also attributed its population decline to habitat fragmentation along the Yangtze River.

From the above timeline mapped out by Chinese scientists, the population of the species below the Gezhouba Dam fell drastically after the dam was constructed in the 1980s.

Later on, another massive dam -- the Three Gorges Dam -- was built on the upper stream of the Yangtze River, which was one of the most biodiversity-rich hotspots in China. 

While dams supply water and electricity to a growing population and fuel economic growth, damming brings about pollution, habitat loss and fragmentation by altering river flow and flooding nearby lands which affect animals and plants negatively.

The Chinese paddlefish is a victim of this development.

The population of Chinese paddlefish eventually dwindled to an amount that was no longer productive. The lack of reproduction led to the demise of this species.

There is no way to resurrect the population as there are no captive individuals and no living tissues of the Chinese paddlefish are conserved.

If you think that keeping these animals in captivity acts as a safety net against diminishing populations, you are wrong too.

Having live specimens does not mean guarantee that entire species can be revived.

For example, the largest freshwater turtle on Earth, the Yangtze giant softshell turtle, is already extinct in the wild despite there being a male and a female in the Suzhou zoo. The two individuals are too old and frail to mate.

10-year fishing ban starts in 2020

The extinction of the Chinese paddlefish highlights the need for greater conservation efforts to protect other endangered species found in the Yangtze river.

This includes the Yangtze River dolphins also known as the baiji which was already declared functionally extinct as well as the finless porpoise and the Chinese sturgeon which are critically-endangered.

Recognising the need to restore the Yangtze river, the Chinese government has launched a 10-year commercial fishing ban in key areas along the river from Jan. 1, 2020.

According to Xinhua, the ban will be implemented in 332 conservation areas in the Yangtze river basin and will extend to all natural waterways and major tributaries in the region by Jan. 1, 2021.

The Vice Minister of Agriculture and Rural Affairs of China, Yu Kangzhen, said that the fishing moratorium is a "key move" to revive the biological resources and biodiversity in the Yangtze river.

Affected fishermen will also be provided with assistance to find new forms of livelihood which includes becoming patrollers and protectors of the river to help enforce the ban.

Hopefully, the ban comes in time to make a difference.

Top photo via Weibo