Development driving mammal’s decline

In China, the finless porpoise is only found in the middle and lower stretches of the Yangtze River, its main tributaries and two adjoining lakes.

With an annual death rate of 5 to 10 percent, the mammal will be functionally extinct in 15 years unless the population can be stabilized or expanded.

In 2013, the International Union for Conservation of Nature classified the species as “critically endangered”, and it was placed under the highest level of State protection in May.

“The porpoise’s natural habitat has been degraded by the development of shipping, overfishing and illegal fishing, the construction of water-related projects and sand excavation,” said Wang Ding, a researcher at the Institute of Hydrobiology.

So far this year, 21 porpoises have been found dead in the river.

“The noise from ships may confuse the echolocation system the porpoises use in the water,” Wang said. “If the porpoise mistakenly believes the noise is that of its companion, it may be injured by a ship’s screw.”

Zhang Xianfeng, director of the Museum of Aquatic Organisms in Wuhan, Hubei province, said: “Sound waves are vital to baby porpoises. The lactation period usually lasts at least six months, during which time the calf and its mother build a communication channel through sound. If the baby confuses noise of a ship with its mother’s call, it will die from lack of milk.”

According to Wang, on-site, off-site and captive breeding are popular conservation methods, but on-site conservation is more difficult than off-site because the river is an open waterway and is congested with ships.

“By contrast, we have seen great achievements in off-site conservation, especially at the Tian’ezhou reserve,” he said.

In 1990, the Tian’ezhou Milu National Nature Reserve in Shishou, Hubei, became home to five finless porpoises.

The number has now risen to 75, and the reserve is regarded as the “seed bank” of the species.