3 October 2020 | New Scientist | 43davidianus) and the Yangtze giant softshell
turtle (Rafetus swinhoei).
Smaller fish are also in trouble. There
are 474 known species of fish in the Yangtze;
the paddlefish survey failed to find 140 of
them. Most of these are probably highly
endangered, according to the team from
the Chinese Academy of Fishery Sciences
which carried out the survey.
The annihilation of the Yangtze biosphere
is entirely down to human activity. Since
the 1950s, the 6300-kilometre river – the
longest in Asia – has undergone explosive
development. A third of China’s population,
some 400 million people, live close to what
is now the world’s busiest river; there are
more than 40 cities beside it including the
vast metropolises of Chongqing, Wuhan,
Nanjing and Shanghai. Until the Gezhouba
dam opened in 1981, it was free-flowing;
other dams including the immense Three
Gorges have since been added and several
more are planned or under construction.
And there is more to come. In 2016,
the government unveiled the Yangtze
River Economic Belt to promote further
development. In the face of this immense
pressure, the paddlefish survey scientists
recently warned that the Yangtze aquatic
ecosystem is in danger of collapse.
The Yangtze is just a drop in a very large
freshwater ocean. All over the world,
freshwater ecosystems and their megafauna
are in trouble. According to a paper Jähnig
co-authored in 2019, “They are among the
most threatened ecosystems globally”.
Some river systems are in even worse
shape than the Yangtze. On a measure of
threat to biodiversity, the Yangtze scores
0.822. Worst of all is the Danube (0.912),
closely followed by the Mississippi (0.900),
Shatt al-Arab (0.898) and the Orange (0.858).broke the news described the extinction
as a “reprehensible and irreparable loss”.
It isn’t the only large animal to have
disappeared from the Yangtze in living
memory. The baiji, aka the Yangtze river
dolphin (Lipotes vexillifer), hasn’t been
sighted since 2002 and is almost certainly
extinct too.
Others are going the same way. The
paddlefish’s close relative, the Chinese
sturgeon (Acipenser sinensis), is on the critical
list, as are the Chinese alligator (Alligator
sinensis), Chinese giant salamander (Andriascentral China. A rescue programme was
launched in 2005, but didn’t work, and an
extensive survey of the entire Yangtze basin
in 2017 and 2018 failed to locate a single one
of these fish. “Given that there hasn’t been a
reliable sighting for so long, there’s not much
hope,” says extinction biologist Dave Roberts
of the University of Kent, UK. In all likelihood,
the last one actually died between 2005 and
2010 and the species was functionally extinct- that is, unable to reproduce – by 1993. There
are no specimens in captivity and hence no
prospect of a comeback. The scientists who
The Chinese paddlefish
(top) is thought to be
extinct, but the American
paddlefish (below)
is still swimmingSH
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