Morphological differences between coastal bottlenose dolphin (Tursiops aduncus) populations identified using non-invasive stereo-laser photogrammetry

Martin van Aswegen; Fredrik Christiansen; John Symons; Janet Mann; Krista Nicholson; Kate Sprogis; Lars Bejder

doi:10.1038/s41598-019-48419-3

Morphological differences between coastal bottlenose dolphin (Tursiops aduncus) populations identified using non-invasive stereo-laser photogrammetry

Sci Rep. 2019 Aug 22;9(1):12235. doi: 10.1038/s41598-019-48419-3.

Authors

Martin van Aswegen^{1

2

3}, Fredrik Christiansen^{4

5

6

7}, John Symons^{4

5}, Janet Mann⁸, Krista Nicholson^{4

5}, Kate Sprogis^{4

5

7}, Lars Bejder^{4

5

9}

Affiliations

¹ Environmental and Conservation Sciences, Murdoch University, South Street, Murdoch, WA, 6150, Australia. mvanas@hawaii.edu.
² Aquatic Megafauna Research Unit, Harry Butler Institute, Murdoch University, South Street, Murdoch, WA, 6150, Australia. mvanas@hawaii.edu.
³ Marine Mammal Research Program, Hawaii Institute of Marine Biology, University of Hawaii at Manoa, 96744, Kaneohe, USA. mvanas@hawaii.edu.
⁴ Environmental and Conservation Sciences, Murdoch University, South Street, Murdoch, WA, 6150, Australia.
⁵ Aquatic Megafauna Research Unit, Harry Butler Institute, Murdoch University, South Street, Murdoch, WA, 6150, Australia.
⁶ Aarhus Institute of Advanced Studies, Høegh-Guldbergs Gade 6B, 8000, Aarhus, Denmark.
⁷ Zoophysiology, Department of Bioscience, Aarhus University, 8000, Aarhus, Denmark.
⁸ Department of Biology and Department of Psychology, Georgetown University, 20057, Washington, DC, USA.
⁹ Marine Mammal Research Program, Hawaii Institute of Marine Biology, University of Hawaii at Manoa, 96744, Kaneohe, USA.

Abstract

Obtaining morphometric data on free-ranging marine megafauna is difficult, as traditional methods rely on post-mortem or live-capture techniques. We linked stereo-laser photogrammetry with long-term demographic data to compare length-at-age (LaA) growth curves of two well-studied populations of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in south-western (SW) and Shark Bay (SB), mid-western Australia. First, we determined the relationship between total length (TL) and blowhole-to-dorsal fin (BH-DF) length from post-mortem subjects (R² = 0.99, n = 12). We then predicted TL from laser-derived BH-DF measurements of 129 and 74 known-age individuals in SW and SB, respectively. Richards growth models best described our LaA data. While birth length (103-110 cm) was similar between study regions, TL estimates at 1, 3, 12, and 25 years differed significantly (p < 0.001). Asymptotic length of adult males (SW = 246 cm, SB = 201 cm) and females (SW = 244 cm, SB = 200 cm) also differed significantly. Morphotypic variations likely reflect regional adaptations to local water temperatures, with the temperate SW having cooler waters than sub-tropical SB. We demonstrate the effectiveness of a non-invasive technique to understand ecological, demographic and life-history characteristics of long-lived marine megafauna, which are critical parameters for informing conservation and management actions.

Publication types

Comparative Study
Evaluation Study
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Animals
Body Size
Bottle-Nosed Dolphin / anatomy & histology*
Bottle-Nosed Dolphin / growth & development*
Female
Male
Photogrammetry / methods*
Western Australia