Mark-recapture analysis of sperm whale (Physeter macrocephalus) photo-id data from the Azores (1987-1995)

Population estimates for female or immature male sperm whales (Physeter macrocephalus) in a region within the Azores archipelago are given, based on photo-identification studies with mark-recapture analysis. The study area encompassed Central Group of islands and island São Miguel. Data indicate that recapture rate animals likely to be females differs from other animals, this heterogeneity is incorporated into models. Closed population (Petersen) estimates, using data summers, suggest between 300-800 summer area. Estimates visits were made model selected Jolly-Seber family. open visiting appeared vary about 400-700 years 1988-1990, increasing by factor three 1,600-2,200 1991-1994. fraction which not suitably marked identification estimated 12%, so these should increased 1.14. These reliable if covers range wider moves out randomly. increase abundance 1991 probably due change composition It yet possible clearly define samples from, nor migration patterns understood. Investigations larger spatial scale needed better understanding.