Population resource evaluation and fishing management strategies of Protosalanx hyalocranius in the Lianhuan Lake

In order to investigate the differences in population characteristics of Protosalanx hyalocranius in different lakes of Lianhuan Lake, Heilongjiang, we estimated key growth and mortality parameters of P. hyalocranius by using the electronic body length frequency method based on fish samples (n=2 801) collected from May to November 2022 in four primary P. hyalocranius-producing lakes of Lianhuan Lake. The current status of P. hyalocranius resource utilization was assessed by constructing the Beverton-Holt dynamic integrated model, and the trend of P. hyalocranius population resources under different fishing strategies was analyzed, so as to formulate a scientific fishing management strategy for P. hyalocranius in Lianhuan Lake. The results showed that there were both supplementary and residual populations of the second age in the Lianhuan Lake. The ELEFAN_SA method yielded an asymptotic length (L_∞) ranging from 173.3 mm to 205.5 mm, an asymptotic body mass (W_∞) from 12.78 g to 25.64 g, and a growth coefficient (k) from 1.9 to 2.3 per year. The total coefficient of mortality (Z) was from 6.32/a to 7.63/a, the coefficient of natural mortality (M) was from 2.07/a to 2.27/a, the coefficient of fishing mortality (F) was from 4.18/a to 5.36/a, and the exploitation rate (E) was from 0.65 to 0.70. Based on the Beverton-Holt dynamic model, the biomass of the residual breeding population accounted for approximately 18%-21% of the total resource. Comparison of the living environment and population resource status indicated that population density and food abundance were the primary factors contributing to growth retardation and miniaturization in P. hyalocranius. By constructing the relative Y'/R of P. hyalocranius in relation to exploitation rate and body length, the results showed that the mean capture body length of HSH Lake, XHL Lake, EBG Lake and NSD Lake were adjusted to 103.98 mm, 123.30 mm, 120.30 mm, 113.58 mm, and the Y'/R value increased by an average of 12.25%. When the exploitation rate of P. hyalocranius was maintained at E_0.1, the residual breeding population biomass could be guaranteed. When the exploitation rate was close to or exceeded the E_max, it was necessary to consider appropriate releases of fertilized eggs. The key factors for the sustainable development of P. hyalocranius resources include adequate food organisms, balanced intraspecific and interspecific relationships, and rational control of resource quantity. The results of this study can be used as a reference for managing P. hyalocranius aquaculture in northern cold-region waters.