Endangered Chinese sturgeon gives up fight to survive
It looks like we are just counting down the days for the Chinese sturgeon, at least in the wild. It has apparently given up breeding in the polluted and dammed Yangtze River, its last stronghold.
According to a report by the Chinese Academy of Fishery Sciences, only about 100 of the massive fish remain. The academy found that the sturgeon did not reproduce naturally at all last year and researchers found no evidence of either eggs or juveniles.
John Platt at Scientific American charts the animal's decline.
That’s quite a change from just 50 or 60 years ago, when a healthy sturgeon fishing industry existed on the Yangtze and nearby rivers. But pollution and the construction of dams took a rapid toll. By the late 1970s, the sturgeon population had dropped to an estimated 10,000 adults. The 1980s saw another drop as the Gezhouba Dam cut off the upper Yangtze and blocked the sturgeons’ migratory route. By 1984, the population of spawning adult sturgeon had fallen to under 2,200.
An adult Chinese sturgeon measures up to 4 metres long, and weighs over 450 kg, making it one the largest sturgeons in the world.
It is anadromous, which means it spends part of its life in saltwater, returning to rivers to breed.
Young sturgeons live in estuaries of the river and along the shoreline nearby.
Sexually mature adults arrive at the mouth of the Yangtze River in June or July to travel up-river to spawn. They reach the middle sections of the river in September or October, where they overwinter.
Before a succession of dams were built along the river, the fish migrated by 2,500 to 3,300 km. Spawning sites often occur in turbulent sections of the river between steep cliffs.
Their roe sticks to gravel on the river-bottom until hatching, with the fry travelling down river to coast where they grow and cycle begins again.
The Yangtze is home to at least two other animals that are heading for extinction thanks to the combination of pollution and damming. The World Wildlife Fund says the Yangtze river dolphin population crashed by 99.4% from 1980 to 2006, and that of the Chinese alligator by 97% from 1955 to 2010.