"Biodiversity in the Yangtze River has been shrinking. The Chinese paddlefish has not been seen in years and the Chinese sturgeon and finless porpoise are on the brink of extinction," said Yu Kangzhen, Vice Minister of Agriculture, at a meeting in Wuhan, capital of central China's Hubei Province, on Thursday.
The numbers of four species of carp have decreased by 97 per cent from the levels in the 1950s, Mr Yu said.
The annual catch from the river is less than 100,000 tonnes, contributing very little to the 69 million tonnes of fishery production nationwide, he said.
The Yangtze River does not have sufficient conditions for fishery production anymore, and it is more important to emphasize its ecological functions and protect aquatic biodiversity, he added.
"People are even fighting for food against the finless porpoise in some places, damaging the reserves," Mr Yu said.
A Ministry of Agriculture four-month fishing ban comes into force in several major rivers including the Yangtze on 1 March. The ban is the first four-month ban in regions south of the Yangtze.
The ministry said it will help fishermen change jobs and impose the ban in a gradual way.
The ban is required by the "No. 1 Central Document" released in February, the first policy statement from the central authorities in the year, and traditionally devoted to agriculture.
The ban has been extended to four months from three and was extended to the Huaihe River last year. This year, the Pearl River and Minjiang River are included for the first time.