Estimates on age, growth, and mortality of Gymnocypris firmispinatus (Cyprinidae: Schizothoracinae) in the Anning River, China

摘要

The age, growth, and mortality of Gymnocypris firmispinatus were studied by 582 individuals that collected between July 2015 and June 2016 from the tributaries of the Anning River, China. The total length (TL) ranged from 27 mm to 242 mm, total weight (W) ranged from 0.2 g to 148.2 g. The relationship of total length and weight was expressed as W=7.754×10-6TL3.304 for the total samples. The age classes of males were 1–9 a, and that of females were 1–13 a. The von Bertalanffy functions based on otolith readings and observed length data were Lt♂=198.6(1–e-0.094 (t+3.497)), and Lt♀=289.3(1–e-0.089 (t+1.109)). The total mortality (Z) of male and female G. firmispinatus was estimated as 0.73/a and 0.40/a, respectively. The natural mortality (M) was evaluated as 0.25/a for males and 0.20/a for females, fishing mortality (F) was 0.35/a for males and 0.16/a for females. The exploitation ratio of the population was 0.66/a for males and 0.50/a for females. It was concluded that the growth of the fish is relatively slower than other congeneric fishes. The population of G. firmispinatus in the tributaries of the Anning River might be in over-exploitation under the current fishing intensity.