Pup production and distribution of breeding Antarctic fur seals (Arctocephalus gazella) at South Georgia

A census of the breeding population of Antarctic fur seals (Arctocephalus gazella) at South Georgia was carried out during the 1990/91 breeding season. Using counts of adult females ashore at the breeding grounds during the pupping period, together with corrections for the likelihood of a female being ashore at a census and for pregnancy rate (71 % in 1990/91), pup production was estimated as 269,000 (95% confidence intervals 188,000 - 350,000). The breeding population in 1990/91 was reduced at long-term study sites probably because of a short term reduction in food availability. Data from these sites were used to estimate the pup production of the population had 1990/91 been a typical year. Based on values from 1983/84 to 1990/91, pup production in 1990/91 would have been 378,000 (S.E. = 19,100) if it had been an average year. The annual increase from 1976/17 to 1990/91 was 9.8% which shows that the rate of increase in pup production has declined since the initial period of population expansion in the 1950s and 1960s. Increased population size has led to an expansion of the breeding range at South Georgia.