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An ecological and behavioural approach for managing boating impacts on dolphins in the dolphin-watching capital of Australia

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posted on 28.03.2022, 21:38 by Andre Steckenreuter
The population of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the newly formed Port Stephens Marine Park, NSW, is the target of the largest dolphin-watching industry in Australia. I investigated (1) potential impacts of dolphin-watching boats (DWs) including aspects such as number of vessels, as well as distances from dolphin groups, (2) different experimental boat approach distances, (3) effectiveness of Speed Restriction Zones (SRZs), and (4) fine-scale habitat use of dolphins, from August 2008 to August 2010. -- (1) The presence of DWs altered both the dolphins' behavioural states and activity budgets. Dolphins spent significantly less time feeding and were never observed to rest in the presence of DWs. These effects were exacerbated as the number of boats increased and the distance from boats decreased, with feeding in particular compromised by boat number. -- (2) Analysis of experimental boat approaches showed that there was significantly less feeding and resting when boats approached them at close range. -- (3) SRZs were more intensely used than Control Zones (CZs) by DWs in summer. In contrast, dolphin groups including calves used SRZs less during summer. -- (4) Spatial modeling of habitat use showed that dolphins preferred shallow areas that are closer to shore for resting but have no preferred habitat when feeding. -- This study recommends stricter regulations than currently legislated including restricting the number of DWs to no more than one within 50 m of a dolphin group with only adults and 150 m with a group including calves to enable groups to feed. Given the critical impact of any boats on resting, the location, size, and accompanying regulations regarding SRZs have to be revised. Total Exclusion Zones should be considered to reduce pressure on dolphins undertaking critically important activities. Management plans whose stated goals include both sustainability of a dolphin-watching industry and longer-term viability of a dolphin population may reconcile conflicting objectives and improve decision-making by using these empirical measures rather than best guesses.

History

Alternative Title

Managing boating impacts on dolphins in the dolphin-watching capital of Australia

Table of Contents

1. Thesis introduction -- 2. Under pressure: spatial modeling identifies crucial resting habitat for resident Indo-Pacific bottlenose dolphins in Australia's dolphin-watch capital -- 3. How does Australia's largest dolphin-watching industry affect the behaviour of a small and resident population of Indo-Pacific bottlenose dolphins? -- 4. Distance does matter: close approaches by boats impede feeding and resting behaviour of Indo-Pacific bottlenose dolphins -- 5. Are speed restriction zones an effective management tool for minimising impacts of boats on dolphins in an Australian marine park? -- 6. Synthesis and management recommendations.

Notes

Includes bibliographical references "August 2011" Thesis by publication.

Awarding Institution

Macquarie University

Degree Type

Thesis PhD

Degree

Thesis (PhD), Macquarie University, Faculty of Science, Graduate School of the Environment (GSE), Marine Mammal Research Group

Department, Centre or School

Graduate School of the Environment.

Year of Award

2012

Principal Supervisor

Robert Harcourt

Additional Supervisor 1

Luciana Möller

Rights

Copyright disclaimer: http://www.copyright.mq.edu.au Copyright Andre Steckenreuter 2012.

Language

English

Jurisdiction

New South Wales

Extent

1 online resource (xii, 153 p.) ill. (some col.), maps

Former Identifiers

mq:71606 http://hdl.handle.net/1959.14/1276176