The Chinese weatherfish has a hidden talent. Upon detecting a shift in atmospheric pressure, its swimming accelerates. Meteorologists would do well to take heed: frantic fish mean a storm is coming.
Weatherfish are just one of many species catalogued in a detailed guide, commissioned by The Nature Conservancy, to the fish of the Yangtze River Basin.
Like the weatherfish, the guide will serve as a barometer of the Yangtze's health, and the information it provides will aid Conservancy scientists as they work to help the river weather a gathering storm of environmental threats including overfishing, pollution, development and climate change.
The environmental health of the Yangtze is crucial to China's future: 400 million people depend on its supplies of fresh water and fish.
Similarly, a wide variety of wildlife species depend on the Yangtze. Some, like the baiji (or Chinese river dolphin), have already gone extinct. Others, like the Chinese alligator and Chinese paddlefish, are gravely endangered.
Paddlefish are one of about 100 fish species that the project's scientists hope to track. The recently compiled first installment of the guide describes the anatomy and habitats of 52 species.
Some of these species are quite common. The silver and bighead carp, for example, are native to eastern Asia but have been introduced elsewhere and are currently threatening the ecological balance of the Great Lakes.
The guide also contains information on the roughly 140 species that live only along the Yangtze. These include the Southern China catfish — an important regional seafood staple — and the Taihu icefish, a delicate, translucent species whose struggle for survival is a model example of the wide range of perils facing the Yangtze's aquatic species.
Like many other species of fish in China, the Taihu icefish is a prized food resource. For years, fishing communities have made a living by drying or freezing the fish and exporting it to Japan and other southeastern countries where it would end up on a plate.
But in recent decades, fisheries have reported smaller catches of the fish, due in part to overfishing. Lake Poyang, China's largest freshwater lake and offshoot of the Yangtze, used to yield nearly 700 tons of the fish per year. As a result of overfishing, the Taihu icefish industry in Lake Poyang has completely collapsed.
Elsewhere, the icefish faces different problems. Waste water from urban industry and rural agriculture has polluted its waters. And many of the lakes along the lower Yangtze that formerly served as sanctuary for the Taihu icefish have disappeared due to the construction of dykes, floodgates and other structures that fragment their river habitat.
By examining the plight of the Taihu icefish as well as other species, the fish guide will play an important role in informing the Conservancy's policy work along the Yangtze and providing on-the-ground conservationists with a blueprint for protecting fish.
For example, the guide explores the challenges faced by the Chinese sturgeon as it attempts to navigate dams while traveling up the Yangtze to spawn. Charting the sturgeon's progress informs the Conservancy's effort to encourage more environment-friendly dam construction throughout the Yangtze River Basin.
By identifying the stretches of the Yangtze most crucial to fish species — and the people whose livelihoods depend on those species — the Conservancy is helping to inform crucial policy debates and devising smart growth for China's hydropower projects along the river.
Information on the first 50 fish species was published in a report in July 2009. The final guide is expected to be available in 2011.July 25, 2012