Individual Occurrence of Male Beluga Whales Delphinapterus leucas in Reproductive and Feeding Aggregations in the White Sea

Being highly social gregarious cetaceans, beluga whales often form seasonal aggregations, differing in sex and age composition and function. Until now, studies of the social structure of belugas in the White Sea (Russia) have been limited to general descriptions of their summer aggregations and female–calf interactions, while the data on males are lacking. In this study, we have analyzed the individual occurrence of identified male White Sea belugas in two different seasonal aggregations based on visual observations and photo-identification data: a summer reproductive gathering near Cape Beluzhiy, Solovetsky Island, Onega Bay (June–August from 1995 to 2022) and a feeding aggregation at the Varzuga River mouth, Kandalaksha Bay, southern coast of the Kola Peninsula (September–October 2023). We have found that the identified males may not only return to summer reproductive areas (like females) but also show fidelity to the same feeding grounds. We have not found stable associations among the identified males in both aggregations, and their formations were apparently cooperative.