Population abundance and ranging patterns

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Background

This research seeks to improve our baseline understanding of coastal bottlenose dolphins using the coastal and estuarine waters off Bunbury, Western Australia. This city of Bunbury is a growing population centre, with plans for port expansion and commercial dolphin tourism activities. As such, improving our understanding of this population’s abundance, ranging patterns, habitat use and behaviour is needed to inform long-term conservation and management efforts for this population.

A bottlenose dolphin leaps out of the waters off Bunbury, WA. Photo: Holly Smith, MUCRU.

Research aims

  1. Examine the status of the dolphin population
  2. Assist with long-term conservation and management

Specific objectives

  • Calculate accurate abundance estimates and determine how many dolphins are in the Bunbury population.
  • Describe group composition, including each animal’s sex and age.
  • Investigate associations and interactions between dolphins.
  • Determine seasonal residency and extent of home ranges.
  • Identify benthic habitat types available to Bunbury dolphins.

Methods

Between March 2007 and February 2010, year-round standard boat-based photo-identific ation techniques were used as a capture-recapture method for documenting individual bottlenose dolphins, based on nicks and marks on the dorsal fin and body surface, encountered along pre-determined transect lines.

The 120 km2 study area was divided into three transect zones (Zone 1: Buffalo Beach; Zone 2: Back Beach; and Zone 3: Bunbury Inner waters; Figure 1). Surveys were conducted from a 5 m centre console research vessel driven at a speed of 8 -12 kn along transect lines. Transects followed a predetermined track in a zig-zag pattern within one nautical mile from shore.

Figure 1. Map of the study area off Bunbury, Western Australia, showing the extent of the zig-zag transects.

Publications

  • Manlik, O., McDonlad, J.A. Mann, J., Raudino, H.C., Bejder, L., Krützen, K., Connor, R.R., Heithaus, M.R., Lacy, R.C. and Sherwin, W.B. (2016).  The relative importance of reproduction and survival for the conservation of two dolphin populations. Ecology and Evolution. doi: 10.1002/ece3.2130
  • Smith, H.C., and Sprogis, K.R. (2016). Seasonal feeding on giant cuttlefish (Sepia apama) by Indo-Pacific bottlenose dolphins (Tursiops aduncus) in south-western Australia. Australian Journal of Zoology. doi: 10.1071/ZO15075
  • Smith, H.C., Frere, C., Kobryn, H. and Bejder, L. (2016). Dolphin sociality, distribution and calving as important behavioural patterns informing management. Animal Conservation. doi: 10.1111/acv.12263
  • Smith H.C., Pollock K.H., Waples K., Bradley, S. and Bejder, L. (2013). Use of the Robust Design to Estimate Seasonal Abundance and Demographic Parameters of a Coastal Bottlenose Dolphin (Tursiops aduncus) Population. PLoS ONE 8:e76574. doi: 10.1371/journal.pone.0076574

Completed PhD thesis

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