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The fatty acid (FA) composition was studied in pink salmon smolts during their migration (from start to ending) in the Indera River and in an experiment with stationary cages (in the river, the estuary, and the White Sea), taking account of differences in water temperature and salinity. Changes in the quantitative composition of FAs (higher contents of total saturated (SFAs) and monounsaturated (MUFAs) FAs and a lower content of polyunsaturated FAs (PUFAs)) were found in smolts in the middle of their downstream migration and in an experimental group kept in cages in the sea for 72 h. The qualitative composition of major FAs (16:0, 18:1(n-9), 20:5(n-3), and 22:6(n-3)) was the same in all of the study groups and was similar to that at earlier stages of pink salmon development. Variations in the contents of 20:5(n-3) and 22:6(n-3) were observed in experimental smolt groups that confirmed the important role of these PUFAs in adaptation of pink salmon smolts to the transition from a freshwater river ecosystem to living in the sea.

During spawning migration and spawning, skeletal muscles of fish serve as a depot of plastic and energy substrates that are actively consumed to maintain viability. The content of water-soluble protein and its oxidized (carbonylated) fraction, as well as the activity of protein-hydrolyzing enzymes (intracellular proteases) in the skeletal muscles of pink salmon Oncorhynchus gorbuscha spawners during spawning migration from the White Sea to the Indera River have been characterized. At the initial stage of the migration route from the sea to the river, a reliable increase in the activity of cathepsin D, which plays a leading role in the degradation of muscle proteins, was noted in the skeletal muscles of pink salmon females, with no reliable quantitative changes in the soluble fraction of proteins. At the same time, during the spawning migration of pink salmon, accumulation of carbonylated proteins, markers of oxidative stress, was observed. It should be emphasized that the described changes are characteristic only of white skeletal muscles; in red muscles (aerobic, providing long-term swimming load), no changes were detected during spawning migration.

Atlantic salmon (Salmo salar) populations in the Arctic River Teno (Tana) and other North Atlantic rivers have declined at the same time as pink salmon (Oncorhynchus gorbuscha) have begun to spawn extensively in these rivers in odd-numbered years. In the River Teno, especially, the number of one-sea-year Atlantic salmon ascendants has decreased. In this short review, we assess, based on current information, how the abundance of pink salmon may weaken the survival of Atlantic salmon. Our hypothesis is based on recent evidence from Atlantic salmon in the Baltic Sea showing that the high marine lipid content in the diet of Atlantic salmon post-smolts impairs their growth and survival and is manifested in low numbers of ascendants and in poor thiamine (vitamin B1) status in both juvenile and spawning Baltic salmon. The high energy density of lipids increases the need for thiamine in the metabolism, and the high content of highly unsaturated fatty acids (n–3 HUFAs), like docosahexaenoic acid (DHA, 22:6n–3), in marine fish lipids increases the rate of lipid peroxidation, which consumes thiamine as it acts as an antioxidant against lipid peroxidation. The review presents information that could be used in planning possible future research on the topic.

Since 2019, the Norwegian Veterinary Institute (NVI) has conducted health monitoring of pink salmon in Norway. The primary purpose of health monitoring has been to examine the presence of selected notifiable infections in pink salmon, but also to gain general knowledge regarding the health of pink salmon to inform assessments of risks to wild and farmed native salmonids. In 2023, post‐mortem examinations were performed on 184 pink salmon captured in rivers Lakselv, Tana, Neiden, Komagelva, Kongsfjordelva and Karpelv in the County of Finnmark, Norway. Tissue samples from 161 of these were analysed with specific PCR assays aimed at detecting infectious salmon anaemia virus (ISAV), viral haemorrhagic septicaemia virus (VHSV), infectious hematopoietic necrosis virus (IHNV), piscine orthoreovirus genotype 1 (PRV‐1) and Renibacterium salmoninarum. In addition, cultivation methods were applied to detect the presence of cultivable virus and bacteria. ISAV, VHSV, IHNV PRV‐1 and R. salmoninarum were not detected by PCR. Furthermore, R. salmoninarum, Aeromonas salmonicida subsp. salmonicida and cultivable virus were not detected by cultivation. With the exception of the absence of PRV‐1, the results correspond to previous years' health‐monitoring projects. Introduction of alien invasive species is a major threat to biodiversity. Introduction and translocation of pathogens has been identified as a hazard pertaining to introduction and spread of pink salmon. Accordingly, risk based and targeted health monitoring of invasive pink salmon is recommended.

Data are presented on changes in the activity of the membrane-bound osmoregulatory enzyme Na + /K + -ATPase and lipid composition in the gills of pink salmon Oncorhynchus gorbuscha during spawning migration from the White Sea to the river environment through the estuary. The compensatory reaction of pink salmon in a hypoosmotic environment is accompanied by a decrease in Na + /K + -ATPase activity and a change in the content of phosphatidylserine and polyunsaturated fatty acids (linoleic, eicosapentaenoic and docosahexaenoic). The results obtained indicate that effective osmoregulation in pink salmon during spawning migration from the sea to the river allows the implementation of a reproductive strategy.

— Thyroid and sex steroid hormones have been studied in spawners of the pink salmon Oncorhynchus gorbuscha at the stage of changing the marine section of the spawning migration path to freshwater one . Males of smaller size enter the Keret River earlier than larger specimens; such differences were not found in females. Compared to specimens in the sea, females in the river are characterized by a high level of triiodothyronine and an increased rate of deiodination, and males have a high testosterone level. Females both in the sea and in the river differ from males by a high level of 17ß-estradiol and a low value of the ratio of testosterone concentrations to 17ß-estradiol.

The experimental study yielded new data on changes in the activity of Na + /K + -ATPase and the level of cortisol in juvenile pink salmon Oncorhynchus gorbuscha that left the spawning nests (Olkhovka River, White Sea basin) during their transfer from fresh water to sea water (25‰) and back. The development of tolerance to increased salinity in juvenile pink salmon is accompanied by activation of Na + /K + -ATPase after 1 h and 24 h of maintaining in seawater and by cortisol content increase after 1 h of this exposure, followed by a return to the initial level after 24 h. The results obtained indicate the readiness of juvenile pink salmon to downstream migration into the marine environment immediately after leaving spawning nests. With the subsequent transfer of fish from salt water to freshwater after 24 h, the activity of Na + /K + -ATPase and the content of cortisol in them decrease, which may indicate the plasticity of the osmoregulatory reaction of pink salmon smolts.

Lipid and fatty acid modifications induced by the effects of various salinity patterns on the juvenile pink salmon Oncorhynchus gorbuscha (the Olkhovka River and the White Sea) within the experiment have been revealed. Concentrations of steroids, saturated fatty acids, and signaling molecules such as phospholipids (phosphatidylserine and phosphatidylinositol) and arachidonic acid under the hyperosmotic stress-related effects (keeping the fish for 1 h in the seawater after the time of transfer from the freswater) tend to increase. Decreases in phosphatidylcholine and n -6 saturated, monounsaturated, and polyunsaturated fatty acids are recorded in the juvenile pink salmon fish kept for 24 h in the seawater after the time of transfer them from the freswater, while the levels of phosphatidylethanolamine and n -3 polyunsaturated fatty acids (especially eicosapentaenoic and docosahexaenoic acids), on the contrary, tend to rise significantly. Lipid composition modifications in the juvenile pink salmon fish kept under the hypoosmotic stress conditions (24 h in freshwater after 24 h in seawater) induce stabilization of functioning the cell membrane structure, since the levels of bioeffectors including phosphatidylserine, phosphatidylinositol, and arachidonic, eicosapentaenoic, and docosahexaenoic acids tend to decrease. A reduced amount of lipids (triacylglycerols) stored as an energy reserve is shown for all the experimental fish groups. The outcomes indicate the high levels of adaptive potential of the juvenile pink salmon fish kept under the effects of abrupt salinity change in the water environments and their readiness for downstream migration not long before leaving the nests.

— The article presents information on the long-term behavior of biological indicators and returns and catches of three species of the Pacific salmon, namely, pink salmon ( Oncorhynchus gorbuscha ), chum salmon ( O. keta ), and coho salmon ( O. kisutch ) for two conditional periods of the end of the 20th century and beginning of the 21st century. A number of changes occurred in the structure of biological indicators during the specified periods of time. There was a synchronous decrease observed in length, body weight, and fecundity in pink salmon, chum salmon, and coho salmon by the end of the second period. Dominant age groups changed in chum salmon and coho salmon, while age of both species increased. Characteristics of the dynamics of pink salmon returns were identified for two major capture fisheries areas, Shelikhov Gulf and Taui Bay. They fluctuated in antiphase along the even- and odd-year lines at the end of the 20th century; odd-year returns were largely recorded at the beginning of the 21st century. Returns have become strong both for even- and odd-year generations since 2015. The chum and coho salmons returns are on the rise. Taui Bay is noted to have lost its commercial importance as the main harvesting area of the pink and chum salmons.

Field experiments and observations revealed that active outcome of pink salmon fry Oncorhynchus gorbuscha into the riverine water current precedes its passive downstream migration. Inherited behavioral reactions (rheoreaction, optomotor reaction, photo- and tigmoreactions) in response to environmental changes determine the outcome.