SEAL PUP COUNTS AS INDICATORS OF POPULATION-SIZE

A simulation model is used to explore variation in the ratio between total population size and pup numbers of a seal population under different life history parameters and sealing regimes. The ratio is shown to vary depending on recruitment and survival rates, but more dramatically according to the quantity, age and sex of seals removed, and the magnitude of disturbance caused by sealing. Ratios of over 5 : 1 would seem appropriate for the South African fur seal Arctocephalus pusillus pusillus based on the current data for the population and the history of sealing and its associated disturbance, and this is larger than ratios previously documented for this species. If a seal population is to be reduced by removing cows, it is important to note that pup numbers will reflect a much lower growth rate than that of the population as a whole.