Estimating total length in damaged carcasses of franciscana dolphins, <i>Pontoporia blainvillei</i>

Danilewicz, Daniel

doi:10.1111/mms.12474

Cited by 1 publication

(2 citation statements)

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“…Using years 1, 3, 12, and 25, we compared dolphin length across periods of both rapid growth and growth approaching an asymptote, while also accounting for regions of the curve where physical maturity has been reached. Years 3 and 12 also coincide with major life history events for T. aduncus : independence (~3–4 years) 50 and the attainment of sexual maturity (~10–12 years) 45,50,71 , respectively. The HPD distributions obtained from the sensitivity analyses were plotted against each other, as the degree of overlapping between the LaA distributions would indicate whether significant differences were present in each age class.…”

Section: Methodsmentioning

confidence: 88%

“…Total length (tip of rostrum to tail notch) is a fundamental morphometric parameter in marine mammal life history studies 71 . With direct estimates of TL being difficult to acquire on free-ranging dolphins 33 , morphometric indices such as BH-DF are instead frequently employed to estimate TL, using well-established allometric relationships derived through stranding and post-mortem subjects 15,29,33 .…”

Section: Methodsmentioning

confidence: 99%

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

Aswegen

Christiansen

Symons

et al. 2019

Sci Rep

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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 (R 2 = 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.

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Section: Methodsmentioning

confidence: 88%