Relative population sizes and trends, and hybridization of fur seals Arctocephalus tropicalis and A. gazella at the Prince Edward Islands, Southern Ocean

Abstract

Fur seals were counted at the Prince Edward Islands during the 1981/1982 austral summer. Classified counts, adjusted for pup undercounting and mortality, pregnancy rate and seasonal haul-out patterns, of Arctocephalus tropicalis and A. gazella are presented. These populations have entered a phase of rapid growth, as indicated by higher rates of population growth than previously found. The possible role of A. gazella immigration is unknown. There has been an increase in the number of breeding localities used by both species. At present the extent of hybridization between these two species appears limited, possibly by behavioural, ecological and genetic processes.