Population dynamics and stock status of Saurogobio dabryi in the lower reaches of the Jialing River

This research was conducted to explore the population dynamics and stock status of Saurogobio dabryi in the lower reaches of the Jialing River. A total of 256 individuals of S. dabryi were collected in the lower reaches of the Jialing River (Hechuan section) from 2015 to 2016. Growth parameters and stock status of S. dabryi population were estimated by using the Fista II Software. The length-weight relationship was W=7.5×10⁻⁵×L^2.58 (R²=0.7311, n=256), and the Von Bertalanffy growth equation was fitted as L=173.811−e^{−0.73(t+0.23)}, where L_∞=173.81 mm, K=0.73, t₀=−0.23. The exploitation rates of the S. dabryi population were 68% and 69% in 2015 and 2016 respectively, exceeding the theoretical maximum exploitation rate (42%), based on the Yield per Recruit model (YPR), which indicated that the S. dabryi population was overexploited. The S. dabryi in the lower reaches of the Jialing River demonstrated negative allometric growth pattern, and r-selection life strategies. Recruitment to the population mainly occurred from April to June, and was unimodal. The population was dominated by younger and small sized individuals. Abundance had been declining due to overfishing and reduction of natural recruitments to the population.