Hydrological regime and morphodynamics of the outlet part of the Kamchatka River, dynamics of mixing zone, patterns of juvenile Pacific salmon distribution and migration in the coastal waters of Kamchatsky Gulf in the zone of operating trap nets were analyzed on the results of complex field works prowided in summer period in 2018–2019; fishing and specifics of sockeye salmon spawning run in the river was described. In the course of analyzing the entire complex of available long-term data, an assessment of the likely impact of some key factors on the dynamics of anadromous migration of sockeye salmon in the Kamchatka River was made; biological statistics of spawners and current state of reproduction of this stock was demonstrated. It is found, that natural environmental factors, neither abiotic nor biotic (including fish health as population internal factor), could not cause disturbance of sockeye salmon spawning run dynamics in the Kamchatka River in recent years. Smoller body size and physiological imperfection of the spawners before the anadromous migration due to effects of high number of pink salmon in recent years are suggested to be the most likely cause of spawning run delay in late sockeye salmon morph. Regime of commercial use of the stock and general increasing pressure on the spawning stock by coastal fisheries are demonstrated to be the strongest outer factors to affect modern state of the resources and sockeye salmon population structure in the Kamchatka River, causing permanent escapement deficiency on spawning grounds in the river basin (first of all in the late morph), and also infact lead to disballance between different subpopulation groups in the composition of the stock. Recommendations in order to provide recovery and sustainable level of the Kamchatka River sockeye salmon stock are given in the perspective of more efficient commercial use of the stock next several years; highlights for further researches are outlined.

The provided researches on the stock abundance dynamics of Pacific salmon in Kamchatka allowed to work out a unite scheme of harvest control rules (HCR) for the most important regional stock utits. The basis data used included the run, escapement and catch in the 1990–2010s. Theoretical and mathematical principles of substantiation the HCR, based on the use of models “stock recruitment”, are demonstrated in the article. Modeling the HCRs is made in view of precautional approuch to effects on salmon stocks, what provides keeping safe the spawning stock and supporting the runs (returns) above the critical mark (buffer reference point). The latter allows to form conditions for the maximum sustainable yield (MSY) of Pacific salmon in Kamchatka. For now similar approuch to the fishery management is indispensable environmental standard of international principles of the rational use of aquatic biological resources. Moreover practical ap- plications of the HCR models suggested are demonstrated in examples of predicted estimates of the returns of the biggest units of salmon stocks of Kamchatka in 2022.

The paper represents results of longterm analysis of the state of the Pacific salmon stocks in Kamchatka River. It is admitted, that high-level effects of fisheries resulted in degradation of the spawning stock (stock abundance) of major local salmon stock units in the basin of Kamchatka River. Commercial importance and previous reproduction potential of all Pacific salmon species has been lost in the mediate and upper parts of the river. This situation was especially noticable in 2018–2020.In view of the trend in the dynamics of salmon stocks in the Kamchatka scientists of KamchatNIRO suggested additional measures of fishery regulation in the Kamchatsky Gulf and Kamchatka River basin. A target strategy of management of fishing Pacific salmon in Kamchatka River was developed as a result, including a complex of limitations to start fishing (catches), a system of stop-fishing days and periods of full stop fishing to provide escapement for spawning.Moreover, regular annual biological monitoring of Pacific salmon of Kamchatka River, provided by KamchatNIRO, was noticeably strengthened with additional hydroacoustic counting and control fishing at the fishery plot № 832. Hydrological-hydroacoustic surveys in Kamchatka Gulf began in 2018 also were to improve the regional scientific monitoring.Results of the surveys 2019–2021 allowed to evaluate current effects of hydrological regime and fishing in Kamchatka Gulf on formation of salmon spawning stocks in Kamchatka River. It has been found, that the changes of the morphodynamics of the Kamchatka River mouth in 2021 resulted in wider area of freshwater effects in Kamchatka Gulf. That was a trigger of redistribution of prespawning salmon aggregations on their migration routs to the river mouth, what eased press of fishing in the area of plots of marine fixed gill nets. In this way the spawning escapement of Pacific salmon into the basin of Kamchatka River this year increased.

Seasonal growth and formation of annual rings on scale of juvenile Pacifi c salmon (Chinook, sockeye, coho and cherry salmons) restart in the Bolshaya River basin from mid May to mid June. In the last half of June and until the end of July, there are actually no additional formations on the scales of both underyearlings and yearlings. In August–October false annual rings (FARs) of dense circuli can be observed on scales of underyearlings of species mentioned above. Forming the extra FARs in the yearlings of coho and cherry salmon during their second season of growth not found (few exceptions only). The underyearling’s FARs are most frequent (17.4%) in Chinook salmon, following by sockeye salmon (12.1%) and coho salmon (7.1%), and the most rare (1.0%) in cherry salmon. The frequency of the FARs in yearlings during their growth period in the fi rst summer is 28.1% in Chinook salmon, 12.6% in sockeye salmon, 11.7% in coho salmon and 4.8% in cherry salmon.

Состояние запасов чавычи р. камчатки в современный период характеризуется ростом численности величины подходов со значительными изменениями структуры; возрастной состав изменился в сторону рыб младших групп и сократилась доля самок. В бассейнах рек с хорошо организованным промыслом, к которым относится и р. камчатка, основным фактором, лимитирующим численность и формирующим биологические показатели лососей, является промысел. Важной частью в раскрытии механизмов воздействия промысла на состояние запасов чавычи является анализ архивных и современных материалов, охватывающих длинные ряды наблюдений. Так, в основу работы положены данные отечественной официальной промысловой статистики по вылову чавычи морским дрифтерным промыслом с 1952 г., прибрежным в камчатском заливе и речным в бассейне р. камчатка-с 1934 г. В настоящее время 80% чавычи р. камчатки стабильно вылавливают ставными неводами, расположенными к югу камчатского залива от устья реки. Основное влияние на степень и характер промыслового использования чавычи в значительной степени обусловлено существованием в бассейне реки многовидового промысла тихоокеанских лососей, причем главным образом добычей основного виданерки. кроме того, наряду с прибрежным промыслом не последнюю роль в существенном изменении структуры родительских стад чавычи, в частности размерно-возрастного и полового состава, сыграл дрифтерный морской лов.