Growth, mortality, and resource utilization of Gymnocypris chui in Langcuo Lake of Tibetan Plateau, China.

Abstract

To investigate the growth, mortality, and resource utilization of Gymnocypris chui in Langcuo Lake of Tibetan Plateau, we measured body length and body weight of 389 fish based on four sampling surveys from October 2018 to November 2019. We identified the ages through lapillus. Based on frequency distribution of body length, we estimated the growth and mortality coefficients of G. chui in Langcuo Lake and the utilization status of existing population resources according to the Beverton-Holt dynamic comprehensive model. The results showed that G. chui were mainly composed of individuals aged 2 to 19 years in Langcuo Lake, with a length-body weight relationship equation of W=0.0105L3.042. The von Bertalanffy growth equation revealed that the fish had an asymptotic body length of L∞=37.28 cm, growth coefficient of k=0.160, and theoretical growth starting age of t0=-0.887 a. The total mortality coefficient Z was estimated as 0.48, based on the length-converted catch curve method. According to Pauly's empirical formula, the natural mortality coefficient M was 0.34, fishing mortality coefficient F was 0.14, and exploitation rate E was 0.29, indicating that G. chui resources in Langcuo Lake were not over-exploited. Considering the growth and mortality of G. chui in Langcuo Lake, fishing is appropriate, with a recommended fishing length of Lc=22.37 cm.