INFLUENCE OF ABIOTIC AND ANTHROPOGENIC FACTORS ON THE USE OF THE BAIKAL SEAL (PUSA SIBIRICA GMELIN, 1788) OF THE SHORE ROOKING ON DOLGIY ISLAND (USHKANY ISLANDS, BAIKAL) ACCORDING TO DATA RELATED TO THE YEAR 2021

Abstract

The usage of the coastal rookeries by the Baikal seal (Pusa sibirica Gm.) under the simultaneous influence of two environmental factors u floating ice disappearance and a rapid and sharp water level increase in the lake Baikal in summer was studies based on video monitoring with stationary cameras, which transmitted information online. Dolgiy Island (Ushkany Islands archipelago, the Lake Baikal), one of the main coastal rookeries of the Baikal seal, was monitored in 2021. This year was distinguished by an unusual ice regimen and a rapid water level rise, which flooded the rookeries. The delayed formation of the first seal haulouts correlated with ice regimen characteristics and was predictable, but the further dynamics of the total number of animals at the rookery differed markedly from those described earlier. The main unexpected observation was that the total number of animals in the coastal rookery was 2–3 times less than in 2020. This cannot be explained with only the rapid flooding of many rookery areas. Moreover, in summer, seals were completely absent from the coastal rookery for long periods (including the days when the weather was favorable). As to the physical condition of the seals at the rookery, their age (size) composition and fatness were not significantly different from those in 2020, but the relative number of molting individuals was noticeably lower, on average 60% vs. 80%, which correlates with the late ice break-up associated with a rapid disappearance of floating ice. About 1/3 of the animals in the haulouts had clearly visible manifestations of the skin and hair pathology of various origins, which is also typical for other years. On the whole, the almost simultaneous impact of the two abiotic factors affected the coastal stage of Baikal seal annual cycle not exactly as it could be expected. Perhaps, to some extent, the absence or small numbers of seals at their haulouts was caused by numerous human visitors (tourists). However, not only by that. It is problematic to make more specific conclusions without reliable information about other coastal rookeries,