BIOLOGY, FISHERIES, AND CONSERVATION OF STURGEONS AND PADDLEFISH IN CHINA

This paper reviews five of the eight species of acipenseriforms that o ccur in China, chiefly those of the Amur and Yangtze rivers. Kaluga Hu so dauricus and Amur sturgeon Acipenser schrenckii are endemic to the Amur River. Both species still support fisheries, but stocks are decli ning due to overfishing. Acipenseriformes of the Yangtze River are pri marily threatened by hydroelectric dams that block free passage to spa wning and feeding areas. The Chinese paddlefish Psephurus gladius now is rare in the Yangtze River system, and its spawning activities were severely limited by completion of the Gezhouba Dam in 1981. Since 1988 , only 3-10 adult paddlefishes per year have been found below the dam. Limited spawning still exists above the dam, but when the new Three G orges Dam is complete, it will further threaten the paddlefish. Artifi cial propagation appears to be the only hope for preventing extinction of P. gladius, but it has yet to be successfully bred in captivity. D abry's sturgeon A. dabryanus is a small, exclusively freshwater sturge on found only in the Yangtze River system. It is concentrated today in reaches of the main stream above Gezhouba Dam. The fishery has been c losed since 1983, but populations continue to decline. Acipenser dabry anus has been cultured since the 1970s, and holds promise for commerci al aquaculture; availability of aquacultural methods offers hope for e nhancing natural populations. The Chinese sturgeon A. sinensis occurs in the Yangtze and Pearl rivers and seas of east Asia. There is still disagreement about the taxonomy of the Pearl and Yangtze River populat ions. The Yangtze River population is anadromous. Adults begin spawnin g at about age 14 years (males) and 21 years (females), and adults spe nd over 15 months in the river for reproduction. Spawning sites of A. sinensis were found every year since 1982 below the Gezhouba Dam, but it seems that insufficient suitable ground is available for spawning. Since 1983, commercial fishing has been prohibited but more measures n eed to be taken such as establishing protected areas and characterizin g critical spawning, summering and wintering habitats.