Studies of inshore dolphins, Tursiops and Sousa, in the Moreton Bay region

Corkeron, Peter James (1989). Studies of inshore dolphins, Tursiops and Sousa, in the Moreton Bay region PhD Thesis, School of Biomedical Sciences, The University of Queensland. doi:10.14264/uql.2016.444

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Author Corkeron, Peter James
Thesis Title Studies of inshore dolphins, Tursiops and Sousa, in the Moreton Bay region
Formatted title
Studies of inshore dolphins, Tursiops and Sousa, in the Moreton Bay region
School, Centre or Institute School of Biomedical Sciences
Institution The University of Queensland
DOI 10.14264/uql.2016.444
Publication date 1989
Thesis type PhD Thesis
Supervisor Michael Bryden
Jiro Kikkawa
Weinrich Breipohl
Total pages 266
Language eng
Subjects 060801 Animal Behaviour
0608 Zoology
Formatted abstract
Observations were made of inshore dolphins in Moreton Bay, Queensland, from May 1984 to February 1987. Three hundred and thirty-four individual bottlenose dolphins (Tursiops truncatus) and 50 Indo-Pacific humpback dolphins (Sousa chinensis) were identified photographically.

Bottlenose dolphins feed around trawlers in Moreton Bay, in a way similar to that described for other parts of the world. There is evidence suggesting that the size of food patches created by trawling influences dolphin group size. The size of bottlenose dolphin groups did not vary with depth or distance from shore. Mixed groups of bottlenose dolphins and were found in association with trawlers.

The social structure of the bottlenose dolphin population of Moreton Bay was investigated through analysis of the association patterns of individually identified dolphins. Classification of similarity matrices constructed using Schaller's index of associations demonstrated that groups (of up to 37 identified individual dolphins) were composed of amalgams of smaller, more stable subgroups of two to five animals. Subgroups of male dolphins formed less stable subgroups which seemed affected by individuals' reproductive condition, and were influenced by calving. Intra-group social structure was studied by classifying "nearest neighbour" estimates derived from photographs. This analysis demonstrated that the female-calf bond remains intact within groups, and while some male subgroups tend to remain together, others do not.

The incidence of shark attack on the bottlenose dolphins in Moreton Bay was estimated from observations of fresh and healed scars judged to have been caused by such attacks. Of the 21 fresh wounds observed, all were caused by large tiger (Galeocerdo cuvieri) and great white (Carcharodon carcharias) sharks, and evidence of attacks peaked in summer. Of 106 animals of known sex, 20 of 35 males and 31 of 71 females showed signs of having been attacked by sharks. While there was no significant difference in the number of male and female bottlenose dolphins with healed bite marks, the incidence of fresh scars on females with very young calves suggested that these dolphins were in more danger of attack than were other age/sex cohorts.

Rates of wound healing were observed in three dolphins. These observations indicate that bottlenose dolphins heal quickly (in a few months) from substantial wounds.

Due to selective sampling within Moreton Bay, unbiased estimates of individual ranging patterns and population size could not be derived.

Convex polygon range estimates were constructed for 91 animals identified on more than nine occasions. The largest observed ranges of bottlenose dolphins in Moreton Bay are larger than those reported elsewhere, up to 254 square kilometres. The study was extended into the nearshore oceanic waters off Moreton and North Stradbroke Islands, where 138 bottlenose dolphins were individually identified. There were no recorded instances of dolphins mving into or out of the bay.  ..............................................................
Keyword Bottlenose dolphin
Dolphins -- Queensland -- Moreton Bay
Chinese white dolphin
Additional Notes Other title: Dolphins in Moreton Bay

Document type: Thesis
Collection: UQ Theses (RHD) - UQ staff and students only
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Created: Tue, 10 Mar 2015, 16:19:37 EST by Nicole Rayner on behalf of Scholarly Communication and Digitisation Service