A recent study suggests that the Chinese swordfish, one of the largest freshwater fish on the planet, is probably already extinct.
The Chinese swordfish, a fish up to seven meters long, was once very common in the Yangtze River. However, as early as the 1970s, the species had to face several threats. At the time, we caught an average of 25 tonnes per year for its flesh and eggs. In 1981, the construction of the Gezhouba dam cut the population in half, preventing certain specimens from going up the river to reproduce.
Little by little, populations then began to decline. The species was listed as critically endangered by the IUCN (International Union for Conservation of Nature) in 1996, and has never recovered. The last living specimen was indeed seen in 2003.
Extinct between 2005 and 2010
Recently, a team of researchers led by Hui Zhang of the Chinese Academy of Fisheries Science in Wuhan, China, conducted a census campaign to assess whether a few specimens could still survive today.
As part of this work, they conducted field surveys in 2017 and 2018 along the Yangtze River and its tributaries. In particular, the researchers placed fishing nets in several strategic places to catch certain species. They also inspected local fish markets.
At the end of their study, they recorded 332 species of fish, but no Chinese swordfish. Based on the latest historical observations, they suggest that the species probably died out between 2005 and 2010. And we are talking about a total extinction here.
“There is no individual in captivity and no living tissue has been preserved for a possible resurrection,” said the researchers. “The fish should therefore be considered extinct according to the criteria of the IUCN Red List”.
The disappearance of this emblematic fish should serve as an example. According to the researchers, more frequent surveys of the watershed would indeed keep a closer eye on the species most in difficulty. Prior to this study, the last comprehensive survey of fish in the river and its tributaries was in 1975.
Several species are particularly concerned, such as the Chinese alligator (Alligator sinensis). However, according to the researchers, if means of conservation are put in place quickly, these reptiles could still be saved.