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Abundance of bottlenose dolphins (Tursiops sp.) in the western gulf of Shark Bay, Western Australia

Nicholson, K., Pollock, K., Krützen, M., Allen, S. and Bejder, L. (2011) Abundance of bottlenose dolphins (Tursiops sp.) in the western gulf of Shark Bay, Western Australia. In: 48th Annual Conference of the Australian Marine Science Association, 3 - 7 July, Fremantle, Western Australia.

Abstract

We use mark-recapture methods applied to photo-identification data to estimate abundance and survival rate of bottlenose dolphins (Tursiops sp.) in the western gulf of Shark Bay, Western Australia. The data used for this study was collected as part of a long-term project assessing factors that drive tool use (foraging with a protective marine sponge over the beak) in bottlenose dolphins. Boat-based photo-identification surveys on dolphin groups were conducted in each austral winter (April-September) between 2007 and 2010 along ten transect lines. Each transect line was repeated 25 times in total over the four winters. To date, a total of 1190 dolphin groups (ca. 55% ‘on transect’ and 45% ‘off transect’) have been photo-identified, resulting in the identification of >400 individual dolphins. The Robust Design was chosen as the appropriate model to estimate abundance and survival rate as temporary emigration could be incorporated in the analysis. This study is the first robust abundance estimation of bottlenose dolphins in part of the western gulf and will serve as a baseline for making future comparisons. This research has both empirical and applied value, since these results allow us to (1) better estimate the proportion of the population that engages in tool use and, thus, address questions centred around behavioural ecology, and (2) assess whether or not future increases in anthropogenic activity may degrade habitat to the extent that population size and behaviour is affected.

Publication Type: Conference Item
Murdoch Affiliation: Centre for Fish and Fisheries Research
School of Biological Sciences and Biotechnology
Conference Website: https://www.amsa.asn.au/conference/amsa2011_freman...
URI: http://researchrepository.murdoch.edu.au/id/eprint/6670
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