Design and field methods for sighting surveys of cetaceans in coastal and riverine habitats |
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Authors: | STEVE DAWSON PAUL WADE† ELISABETH SLOOTEN‡ JAY BARLOW§ |
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Institution: | Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand,;National Marine Mammal Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115, USA,;Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand,;National Marine Fisheries Service, 8604 La Jolla Shores Drive, CA 92037, USA |
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Abstract: | - 1 Dolphins and porpoises in coastal and/or riverine habitats face serious conservation threats, yet surveys of their abundance are often especially difficult due to the challenges imposed by the habitats. Because many of these species occur in developing countries, lack of resources imposes a further set of challenges.
- 2 We offer advice on designing and conducting line‐transect surveys with a focus on sound, practical, design rather than analytical sophistication, and we attempt, where possible, to offer simple, inexpensive solutions.
- 3 We guide the reader through the questions of what kind of survey should be done, whether by boat or aircraft, and we discuss ways to avoid bias and increase precision.
- 4 Our treatment of field methods focuses especially on robust, but low‐cost, approaches. We provide two case studies to illustrate the implementation of these ideas.
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Keywords: | abundance aerial boat dolphin porpoise trends |
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