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Dusky dolphins (Lagenorhynchus obscurus) in New Zealand waters Present knowledge and research goals

Dusky dolphins (Lagenorhynchus obscurus) in New Zealand waters Present knowledge and research goals
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  Dusky dolphins (   Lagenorhynchus obscurus  ) in New Zealand waters Present knowledge and research goals Bernd W  ü rsig, Nicholas Duprey and Jody Weir  DOC RESEARCH & DEVELOPMENT SERIES 270 Published by Science & Technical Publishing Department of Conservation PO Box 10420, The Terrace  Wellington 6143, New Zealand   DOC Research & Development Series  is a published record of scientific research carried out, or advice given, by Department of Conservation staff or external contractors funded by DOC. It comprises reports and short communications that are peer-reviewed.Individual contributions to the series are first released on the departmental website in pdf form. Hardcopy is printed, bound, and distributed at regular intervals. Titles are also listed in our catalogue on the website, refer www.doc.govt.nz under  Publications , then Science & technical  .© Copyright April 2007, New Zealand Department of ConservationISSN 1176–8886ISBN 978–0–478–14178–8 (Hardcopy)ISBN 978–0–478–14179–5 (Web PDF)This report was prepared for publication by Science & Technical Publishing; editing and layout by  Amanda Todd. Publication was approved by the Chief Scientist (Research, Development & Improvement Division), Department of Conservation, Wellington, New Zealand.In the interest of forest conservation, we support paperless electronic publishing. When printing, recycled paper is used wherever possible.  CONTENTS  Abstract 51. Introduction 62. Distribution and movement patterns 82.1 Global 82.2 New Zealand 82.2.1 Distribution 82.2.2 Movement patterns 102.3 Kaikoura 112.3.1 The marine environment 112.3.2 Distribution 112.3.3 Seasonal and intra-seasonal trends 122.3.4 Diurnal and nocturnal trends 123. Population biology and behaviour 133.1 Population size and individual residency 133.2 Genetics 133.3 Diet 133.4 Nocturnal foraging strategies 143.5 Behaviours and activities 143.6 Reproduction 154. Tourism impacts 154.1 Research into effects of dolphin-based tourism 164.1.1 Methodology used 164.1.2 Directed studies 174.1.3 Effects of tourism on behaviour 194.2 Recent tourism-related activities 194.2.1 Shore-based descriptions 194.2.2 Boat-based studies: distribution and behaviour of nursery groups 215. Future research directions 225.1 Data from tourism 236. General conclusions and recommendations 247. Acknowledgements 258. References 26  5  DOC Research & Development Series 270 Dusky dolphins (   Lagenorhynchus obscurus  ) in New Zealand waters Present knowledge and research goals Bernd Würsig, Nicholas Duprey and Jody Weir  Texas A&M University, 4700 Avenue U, Building 303, Galveston, Texas, 77551 USA. Email: wursigb@tamug.edu  ABSTRACT Dusky dolphins (   Lagenorhynchus obscurus  ) occur near shore and in  waters up to c. 2000 m in depth in much of the cooler-temperate southern hemisphere. In New Zealand, they are found off most of the South Island and the southern part of the North Island, but have been studied intensively in only two areas, Kaikoura and Admiralty Bay, South Island. Dusky dolphins off Kaikoura have been investigated since 1984 by radio tracking, shore-based theodolite (surveyor’s) tracking, and boat-based behavioural descriptions and photographic identification of natural markings; in Admiralty Bay, theodolite tracking and boat-based studies have been conducted since 1998. Off Kaikoura, dusky dolphins feed at night on myctophids and squid; in Admiralty Bay, they feed during the daytime on schooling fishes in shallow waters. Group sizes, behaviours, social affiliations and general habitat-use patterns differ between Kaikoura and Admiralty Bay, even though some of the same animals utilise both habitats in different seasons. Off Kaikoura, there are daily and seasonal differences in behaviours and movement patterns, with daytime rests around midday, social activities in the mornings and afternoons, and feeding in deeper oceanic waters at night. The discovery of midday resting has led to a voluntary ‘down-time’ of no tourism boats by a local dolphin tourism enterprise, Dolphin Encounter. Dolphins tend to move in deeper  waters in winter than in summer, but there is great variation in the areas traversed. Research is making inroads into understanding dusky dolphin social dynamics, foraging strategies and predator avoidance tactics. Basic research is being augmented by targeted investigations into tourism effects, to allow recommendations to be made on permitted areas, times and numbers. Keywords: cetacean, dusky dolphin,  Lagenorhynchus obscurus , marine mammal, delphinid, habitat use, dolphin tourism, dolphin behaviour, marine mammal tourism, swim-with-dolphin tourism © April 2007, New Zealand Department of Conservation. This paper may be cited as: W  ü rsig, B.; Duprey, N.; Weir, J. 2007: Dusky dolphins (   Lagenorhynchus obscurus  ) in New Zealand waters: present knowledge and research goals.  DOC Research &  Development Series 270 . Department of Conservation, Wellington. 28 p.
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