AGE-SEX STRUCTURE AND POTENTIAL FOR REPRO DUCTION OF PUSA-SIBIRICA (PINNIPEDIA, PHOCIDAE)

Dynamics of sex-age pattern and reproductive potential of the Baikal s eal population (Pusa sibirica Gm.) based on the data obtained in sprin g and autumn expeditions of 1988-1995 and the published materials (196 1-1985) are analysed. Dominance of females in the population is shown to depend on their age; the sex ratio for the investigated period did not change significantly, the portion of females being reduced somewha t in the 90s. There were no actual variations in the age structure, th ough a tendency towards increasing order animals by the late 80s was o bserved. The reproductive potential was kept low by the late 80s (late maturing of females, 30% of dry adult females and oth.) and related t o the epizooty of 1987/1988. Recently the situation has changed for th e better: in the 90s 4-5-year-old females gave birth to 11% of all cub s (70% of the seals were dry), the percentage of dry mature females re duced to 17-20%, the older females, which are maximum fertile, made th e greatest contribution to the population numbers, the average age of their being 6-7 years.