Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences

Abundance, site fidelity and range patterns of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in two Australian subtropical estuaries

Christine A. Fury A B and Peter L. Harrison A

A Southern Cross University Whale Research Centre, School of Environmental Science and Management, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia.

B Corresponding author. Email:

Marine and Freshwater Research 59(11) 1015-1027
Submitted: 4 April 2008  Accepted: 1 September 2008   Published: 27 November 2008


Bottlenose dolphins are widely studied in marine habitats, but information on estuarine populations is very limited. The present study provides the first published data on bottlenose dolphins in Australian estuaries. Abundance estimates, site fidelity and individual ranging patterns were examined over a 3-year period for Indo-Pacific bottlenose dolphins (Tursiops aduncus) inhabiting the Clarence River (CR) and Richmond River (RR) estuaries in northern New South Wales, Australia. Mark–recapture analyses estimated 71 (62–81 95% CI) dolphins utilised the CR whereas 34 (19–49 95% CI) used the RR. Differences in site fidelity were observed between the estuaries, with 60% and 37% of identified dolphins determined as residents, 26% and 21% as occasional visitors and 14% and 42% as transients for the CR and RR respectively. Resource partitioning was apparent in both estuaries with the mean distance resident dolphins were found upstream from the river mouth being greater than occasional visitors and transients. The Clarence River sustains a larger, predominantly resident dolphin community compared with the Richmond River, which supports a relatively small dolphin community with lower site fidelity. Management of future increased anthropogenic disturbances is needed to ensure the long-term survival of these dolphin populations.

Additional keywords: closed population, estuary, population size, ranging patterns, residency patterns.


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