Reproduction, biometric patterns of pink salmon and effect of commercial fishery on the runs of the species on the south of the north-eastern coast of Sakhalin Island in 2021

Abstract

Purpose: to present up-to-date data on the dynamics of the spawning run, reproduction conditions and biometric characteristics of pink salmon in three reference watercourses in the southern part of the north-eastern  coast of Sakhalin Island, as well as analysis of impact of commercial fishing on the spawning run and distribution of spawners within spawning grounds. Methods: common methods of ichthyological research were applied to collect and process field data. Data were  synthesized in MS Excel, analysis and visualization were carried out in MS Excel and Statistica. Scientific novelty: results of monitoring of pink salmon in the southern part of the north-eastern coast of  Sakhalin are presented. Despite the intensive commercial fishery in this area, there are no other data on the  dynamics of pink salmon runs, density of breeders on spawning grounds, and biometric characteristics of  spawners, except for those presented in this paper. Result: data on the timing of spawning migration, distribution of pink salmon within spawning grounds and  degree of occupation of spawning grounds, temporal structure of spawning run; bio-metric characteristics of  pink salmon are presented. Assessment of the influence of commercial fishing on the dynamics of spawning  run and distribution of pink salmon within spawning grounds is discussed.  Practical relevance: the presented data is an integral part of information supply of fishery research of the most  widespread species of Pacific salmon - pink salmon, which forms the basis of salmon fishery in the Sakhalin  Region. Also, the presented data is applicable for preparation of scientifically-based recommendations for  optimizing the fishing pressure.