Results of a comparative assessment of the biological status of juvenile chum salmon Oncorhynchus of natural and artificial origin in individual rivers of the Shelikhov Bay, Magadan coast of the Sea of Okhotsk

The results of a comparative assessment of the biological condition of juvenile chum salmon Oncorhynchus keta (Walbaum, 1792) of artificial and natural origin in the reservoirs of Shelikhov Bay (Magadan coast of the Sea of Okhotsk) are presented. The studies were conducted in 2025 on the basis of the salmon fish-breeding workshop of LLC Magadan Fish Company-2 (LRZ LLC MRC-2) and in the natural conditions of the Gatchan River. The size and weight indicators, indices of internal organs (heart, liver, and gastrointestinal tract), and feeding intensity were compared between farmed and natural juveniles. It was found that there were no significant differences in body length and weight between the groups. However, the indices of the liver and gastrointestinal tract, as well as the index of their filling and the proportion of feeding individuals, were significantly higher in farmed chum salmon, indicating better feeding conditions in the cage.The results confirm that the factory-reared juveniles are not inferior to the natural ones in terms of their main biometric parameters, but they differ in their morphophysiological characteristics, which are influenced by the conditions of their rearing. This study highlights the importance of monitoring the quality indicators of juveniles at private fish farms in order to optimize the technologies of artificial reproduction of Pacific salmon in the region.