Abstracts Category : Other

Feasibility and applications of non-invasive laser photogrammetry on free-ranging coastal dolphins

by Aswegen Martin van

Morphometric data plays a pivotal role in understanding key life history traits to elucidate biological, ecological and evolutionary processes. Obtaining morphometric data from free-ranging cetaceans is difficult, as traditional methods rely on either post-mortem or highly invasive techniques. The present study evaluated the feasibility of remote laser photogrammetry as a non-invasive technique to obtain morphometric data on free-ranging coastal dolphins. First, simulation models and post-mortem specimens were used to investigate potential sources of measurement error and quantify their influence on the accuracy and precision of the morphometric data. These sources include horizontal angle, distance, and body curvature. Second, to demonstrate the potential applications of this technique, laser photogrammetry measurements were obtained during boat-based photo identification surveys on Indo-Pacific bottlenose dolphins (Tursiops aduncus) from Western Australia (Bunbury, Shark Bay and Mandurah). Laser-derived, blowhole-to-dorsal fin (BH-DF) measurements were obtained from individuals of known ages in Bunbury (N=103) and Shark Bay (N=76), in addition to individuals in Mandurah (N=28). Our laser-derived measurement data facilitated the development of population growth curves in conjunction with longitudinal demographic data from Bunbury (~10 years) and Shark Bay (~33 years). These growth curves characterise not only the relationship between age and length, but also the significant morphological differences between these geographically-isolated populations. This study demonstrates the value of remote laser photogrammetry as an effective tool to investigate individual and population-based growth and life-history parameters. This non-invasive technique will provide unique opportunities to better understand the ecological, demographic and life-history characteristics of a population and so better inform conservation management strategies for free-ranging cetacean populations.Advisors/Committee Members: Bejder, Lars, Christiansen, Fredrik.