Downstream migration of pink salmon into the R. Savushkina Paramushir Island (Northern Kuriles) in the spring-summer period of 2021

Abstract

The purpose of these studies is to form the scientific foundations for effective management of the salmon industry in the Russian Far East.

Methods used: research work was carried out in accordance with the standard methods used in the fisheries research.

Novelty: work in this area is being carried out for the first time in the last decade.

The results of the study the downstream migration of pink salmon Oncorhynchus gorbuscha, carried out in the R. Savushkina Island Paramushir Northern Kuril Islands (Sakhalin Region) in the spring-summer period. In total, 18 catches were carried out at night. The data on the daily dynamics of the downstream migration intensity are presented. It was noted that the maximum number of juveniles rolled down in the first two hours of a new day, which corresponded to astronomical midnight. The indices of the size-mass characteristics of down-stream migrants of pink salmon did not change over the entire observation period. The work provides a brief description of the river. Measurements of temperature indicators were taken every hour (from 21:00 to 06:00) during the actual work. At the end of May, the water temperature did not exceed 3 ºС, water warming up above 5 ºС at night was observed only by the third decade of June. The river flow rate was determined immediately before the start of the research. Fluctuations in the river flow rate ranged from 0,175 m/s to 0,662 m/s, and depended directly on the tidal currents and the level of precipitation.

Practical significance: he results of the comprehensive work carried out in 2021 will be used to account for the abundance of Pacific salmon and their rational use, as well as in the preparation of forecasts of the recommended volume of harvest (catch) of the investigated units of aquatic biological resources in the coming years.