In addition, post-mortem specimens may provide a biased sample, if animals of specific age, sex, size or health are more likely to strand, be incidentally caught or killed 22. The dependence on post-mortem study subjects has the disadvantage of reliance on unpredictable access to animals and small sample sizes 21. Post-mortem specimens are usually sourced from stranding events 18 in addition to incidental 19 and deliberate kills 20. Traditionally, three approaches have been used to obtain morphometric data on cetaceans: post-mortem specimens 13, live captive study subjects 14, 15, and capture-release programs 16, 17. Despite its many applications, obtaining accurate morphometric data on free-ranging cetaceans is challenging. Morphometric data of cetaceans contribute to the assessment of individual- and population-based reproduction 4, 5, health 6, 7 and demography 8, 9, 10 and in conjunction with genetic information, taxonomic status 11, 12.

Such parameters are linked to morphological and age-specific processes, often regulated by physiological, ecological, evolutionary, and anthropogenic factors 3. 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.Ī comprehensive understanding of population-specific demographics, life-history traits and behavioural ecology is essential for the effective management of long-lived, slow-reproducing species 1, 2. Morphotypic variations likely reflect regional adaptations to local water temperatures, with the temperate SW having cooler waters than sub-tropical SB. Asymptotic length of adult males (SW = 246 cm, SB = 201 cm) and females (SW = 244 cm, SB = 200 cm) also differed significantly. 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). Richards growth models best described our LaA data. We then predicted TL from laser-derived BH-DF measurements of 129 and 74 known-age individuals in SW and SB, respectively. First, we determined the relationship between total length (TL) and blowhole-to-dorsal fin (BH-DF) length from post-mortem subjects (R 2 = 0.99, n = 12).

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.

Obtaining morphometric data on free-ranging marine megafauna is difficult, as traditional methods rely on post-mortem or live-capture techniques.

Laser dolphin america