Studies of the structure of the Solovetsky reproductive gathering of beluga whales (Delphinapterus leucas) in the White Sea using the photo identification method

The structure of the reproductive gathering of beluga whales (RG) was studied near Cape Beluzhii in the Solovetsky Islands in the White Sea by the photo identification of individuals in 2007–2008; in addition, the peculiarities of the seasonal and interseasonal dynamics of the RG incomings were analyzed. The gathering is formed by predominantly females and calves of different ages, which visit the RG area as stable “family” groups. About 15% of the observed females come to Beluzhii Cape every year and stay there during the whole summer season; thus, forming the regular part of the RG. The other animals come there for a certain time period, which is probably preconditioned by their physiological readiness for coupling and procreation for some of the females. When comparing our data with the catalogue of the visually registered beluga whales’ markers (1996–2008), we found that most of the identified animals of the Solovetsky RG appear here during one summer season or even with an off period of several years despite the significantly regular findings of most of them for this area. We conclude this may be linked with the natural changes of the individual markers due both to the shedding and the sexual cycle in the mature animals. Our data allow concluding that the total population of the Solovetsky PG is higher than was reported before using the visual supervision methods.