Several barrels of fry flowed down into the Yellow River from a fishing vessel and disappeared into the waves. On September 11, 1.04 million fish fry were released at the Nanguotou dam of the Yellow River in Zhengzhou, the capital city of central China's Henan Province.

Among the released fry were silver carp, bighead carp, grass carp, Huanghe carp and crucian carp, all indigenous to the Yellow River.

"Only if all the people stand together to protect fishery resources in the Yellow River, then these species could multiply and diversify," said Feng Jianxin, the chief engineer in Henan Academy of Fishery Sciences.

First time needs quality endorsement

"From this year onward, due all the released fishes in Zhengzhou, we need to invite relevant experts to do a quality endorsement," said Hu Jinwen, the chief engineer in Zhengzhou Fishery Bureau. The purpose of this validation is to guarantee that the released fishes can adapt to their new environment in the Yellow River and that they will do no harm to other fishes.

"There is a release rule: we must release only those species that have previously existed in the river. Fish that live in one body of water are part of a selective gene pool. Exotic species will very likely destroy an original gene pool," stated Hu.

Previously Zhengzhou had introduced other exotic carp species into the Yellow River, leading to the near extinction of the pure Huanghe carp due to crossbreeding.

Prompt protection of the fish in Yellow River

Feng Jianxin explained that there were more than 60 types of common fishes in southern side of the Yellow River in the 1970s. "But according to this year's survey, we have only recorded 20 types of fishes," said Feng.

The northern bronze gudgeon (commonly called "pigeon fish") used to be a valuable fish with a delicious taste in southern side of the Yellow River; it has not been seen for many years. The Kaifeng fish, a distinctive type of small and middle-sized financially lucrative species in Henan part of the Yellow River, has also gone out of sight.

But the situation is improving gradually. "After last year's fry release, the number of catchable fish in the Yellow River has increased by 20 percent," said Wang Xinping, the deputy director of Zhengzhou Fishery Bureau.

At least 6 years to improve resources

"To markedly improve fish resources in the Yellow River, these released fishes need to reproduce three generations," said Feng, "This process, predicted by ideal conditions where no damage influences the ecological environment around the Yellow River area, requires at least six years."

The environment for these fishes along the Zhengzhou part of the Yellow River faces three major threats.

"Water transition and sand transition pose the biggest threats to the fishes along Zhengzhou water region. Every year, almost an entire layer of suffocated fish floats on top of the water surface where the Yellow River has strong currents that cause underwater sandstorms," Feng stated.

Also, both the decrease in water volume and the deterioration of water quality has threatened the life of fishes in Yellow River.

Finally, the lack of ideal spawning grounds had led to low fish breeding rates. It is said that the fish like to spawn along the tranquil river bends. Such areas, however, have decreased because of declining the water levels. "We need to build a spawning area for fish that allows them to reproduce peacefully," said Feng.

(China Development Gateway by Sun Wan September 29, 2007)