Abstract
From October 2001 to June 2003 we photo-identified 55 (including 12 calves) Indo-Pacific bottlenose dolphins (Tursiops aduncus) within the Swan-Canning Estuary in Perth, Western Australia (n = 223 survey days). Analyses of occupancy, ranging and association patterns among adults and sub-adults (n = 43, 78%) identified two main groupings: (a) transient - dolphins sighted only once and generally near the estuary mouth (n = 13, 30.2%) and (b) resident - dolphins consistently observed (n > 23 sightings) throughout the estuary (n = 18, 41.9%). Analysis of the association patterns of resident dolphins showed four groupings: two dyads of adult males; one group of adult females; and one group of sub-adults (STRESS < 0.2 and Lagged association rate (LAR) > Null LAR). The small size of the resident community and the deaths of six dolphins within the estuary in 2009 emphasise the need for new research. As part of a broader study of dolphins in the Perth metropolitan waters, from June 2011 we have been conducting systematic boat-based surveys within the estuary and adjacent waters using belt transect sampling. The aims of this research are to: (1) estimate dolphin abundance across the study area using photo-identification and mark-recapture methods; (2) determine individual residency and ranging patterns in order to better understand site fidelity and population structure; (3) determine habitat use patterns through habitat modelling; and (4) collect behavioural, environmental, and epidemiological data related to interactions with human activities and dolphin health (e.g. entanglements, epidermal diseases).