Abstract: The population structure of Protosalanx chinensis is affected by a variety of factors, including water environment, intraspecific differentiation, interspecific competition and commercial fishing. To investigate the growth performance and the current status of resource utilization of P. chinensis in two important fish farming grounds (Dalong Lake and Amuta Lake) in Daqing, Northeast China, we collected 1513 P. chinensis samples from April to December 2018 for measurement and recording the basic biological characteristics. We estimated the parameters including population growth, mortality and exploitation using Von Bertalanffy growth formula, Beverton-Holt model, Pauly’s empirical formula and length-based Bayesian biomass estimation method. The results showed that the asymptotic body lengths of Dalong Lake (n=660) and Amuta Lake (n=853) populations were 183.75 and 169.10 mm, respectively. The growth performance indices were both 4.85, and the body mass growth equations were W_t=29.29×(1-e^-2.1(t+0.07))^3.2977 and W_t=28.72×(1-e^-2.5(t+0.07))^3.4168, respectively. The ages at inflection were 0.49 a and 0.43 a, and the condition factors were 5.30×10^-4±1.38×10^-4 and 4.00×10^-4±1.61×10^-4. The exploitation rates were 0.60 and 0.61, and the relative catch per unit of supplementation were 0.069 and 0.075, respectively. The current differences in population resources between Dalong Lake and Amuta Lake in Daqing were mainly manifested in the parameters related to growth characteristics. The main reason for such differences was changes in the survival conditions of P. chinensis populations after the period of dietary transition induced by the density differences.

Key words: Protosalanx chinensis, Dalong Lake, Amuta Lake, body length frequency, population dynamics, differential analysis