Reproductive characteristics of Ancherythroculter nigrocauda, an endemic fish in the upper Yangtze River, China

Knowledge on the reproductive biology of fishes is critical for understanding a species' life history and devising appropriate management strategies. Anthropogenic forces, such as damming and overfishing, threaten fishes endemic to the upper Yangtze River. We conducted a study on the reproductive biology of an endemic species, Ancherythroculter nigrocauda in order to provide information on the life history of this species and to assist in its conservation. From July 2011 to June 2012, a total of 417 fishes were captured via monthly sampling by fishermen in the Longxi River, a tributary in the upper Yangtze River. Although the female-male ratio was 1:1.03, females were predominantly larger in body size. Gonad somatic indices and oocyte diameter distribution showed that the spawning period of A. nigrocauda in the Longxi River ranged from April to August, with the peak in April. Body length at 50 % sexual maturity of A. nigrocauda was estimated to be 125 and 106 mm for females and males, respectively. Absolute fecundity of A. nigrocauda varied between 11,300 and 504,630 eggs, with the mean of 162,377 eggs. In conclusion, A. nigrocauda mature early, spawn once, and are highly fecund, all of which are consistent with an r-selected life history. It is recommended that a moratorium on fishing this species be enacted and the culture of this species be continued.