New publication: complex prey-handling of dolphins on giant cuttlefish

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We are pleased to announce the following publication in the Australian Journal of Zoology.

Seasonal feeding on giant cuttlefish (Sepia apama) by Indo-Pacific bottlenose dolphins (Tursiops aduncus) in south-western Australia.

Authors: Holly C. Smith and Kate R. Sprogis

Highlights include:

  • Complex prey-handling by Indo-Pacific bottlenose dolphins on giant cuttlefish was observed (figure 1), involving a six step process (figure 2).
  • All feeding events were observed in relatively shallow coastal waters during the cooler months of July to September (figure 3).
  • Fifteen photo-identified dolphins were observed feeding on cuttlefish (with some individuals were observed feeding on cuttlefish multiple times).
  • Of these 15 dolphins, 12 were identified as adult females.
  • Information on giant cuttlefish along the coastal waters of Bunbury is required as there may be potential impacts to the cuttlefish population from the desalination plant installed in 2010 (which expels hyper-saline water, figure 3).
Dolphin and cuttle on rostrum_Holly Smith_MUCRU

Figure 1. A dolphin with the mantle of a cuttlefish around it’s rostrum, off Bunbury, WA.

Abstract:

We report on observations of Indo-Pacific bottlenose dolphins (Tursiops aduncus) feeding on giant cuttlefish (Sepia apama) from March 2007 to April 2013 in the temperate waters off Bunbury, south-western Australia. Seventeen feeding events were observed during the cooler months between July and September in relatively shallow coastal waters, with 12 dolphins identified as adult females. We observed behavioural sequences of complex prey-handling of cuttlefish where dolphins’ used multiple steps to remove the cuttlefish head, ink and cuttlebone before consuming the flesh of the cuttlefish mantle. Our study provides valuable information to the limited knowledge on the complex prey-handling by T. aduncus on cuttlefish in Australia, and is complementary to other known specialised foraging behaviours of bottlenose dolphins. This study also details a different behavioural sequence of cuttlefish prey-handling to that of the bottlenose dolphins in the Sado estuary, Portugal, where only the head is consumed, and to the Spencer Gulf, Australia, in that the dolphins in Bunbury carry the cuttlefish mantle over their rostrum before removing the cuttlebone. Information on S. apama in Bunbury is scarce, therefore studies on abundance, distribution and egg-laying sites are recommended in order to enable informed decision making and to understand the importance of S. apama to the diet of T. aduncus.

Figure 3_Final drawing

Figure 2. Illustration of the steps in the behavioural sequence of complex prey-handling by bottlenose dolphins feeding on giant cuttlefish off Bunbury, south-western Australia. Step 5 took place under water, where the cuttlebone was released from the cuttlefish mantle. Step 5 was not directly observed and therefore not included in the illustration. Figure courtesy of www.suekalab.com.

About:

During Dr Holly Raudino’s (nee Smith) and Dr Kate Sprogis’s PhD field work they observed opportunistic behavioural events of bottlenose dolphins feeding on giant cuttlefish (Figure 3). Holly and Kate’s PhD’s were undertaken through the South West Marine Research Program in Bunbury, Western Australia, covering an area of 540km2 (Figure 3). For related field blogs about dolphin foraging behaviour in Bunbury see here and here.

Figure 1

Figure 3. The study site off Bunbury, south-western Australia (540 km2). Boat-based surveys were conducted along zig-zag transect lines for photo-identification of bottlenose dolphins. Dolphin logos represent the locations where the cuttlefish feeding events were sighted.

Download the paper:

The publication can be downloaded from the Australian Journal of Zoology, or alternatively, if you are unable to download the article please email Holly at holly.raudino at dpaw.wa.gov.au, or download a copy through Kate Sprogis’s Research Gate.

Citation:

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: http://dx.doi.org/10.1071/ZO15075.

Other SWMRP project publications:

Our publications made possible through the South West Marine Research Program:

Capel, Western Australia, Australia

Figure 4. An adult female dolphin, “Lunchbox”, carrying a cuttlefish in her mouth.

Acknowledgements:

We thank our numerous research assistants who volunteered for the South West Marine Research Program and the Bunbury Dolphin Discovery Centre. Sincere thanks to Sue Kalab (www.suekalab.com) for her illustration. Thank you to Simon Allen for constructive comments on an earlier draft of the manuscript. Thank you to Marianne Cannon, Delphine Chabanne, and Krista Nicholson for coordinating previous field seasons. Sincere thanks for our support that was secured by Professor Lars Bejder, group leader for the Murdoch University Cetacean Research Unit.

Project Funding:

Funding was generously provided by the Bunbury South West Marine Research Programs partners, including Bemax Cable Sands, Bunbury Dolphin Discovery Centre, Bunbury Port Authority, City of Bunbury, Cristal Global, the Department of Parks and Wildlife in Western Australia, IIuka, Bemax, Millard Marine, Naturaliste Charters, Newmont Boddington Gold, South West Development Commission, WA Plantation Resources, BHP Billiton Worsley Alumina.

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