How to weigh an elephant seal with one finger: a simple three-dimensional photogrammetric application

Aquatic Biology

W. Chris Oosthuizen¹  P. J. Nico de Bruyn¹  Marthán N. Bester¹  Alejandro R. Carlini¹ 

关键词: Southern elephant seal;    Mass estimation;    Volume estimation;    Body size;    Field method;    Photography;    Life history;    Phocids;   

DOI  :  10.3354/ab00135

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Several studies have developed photogrammetric techniques for indirect mass estimation of seals. Unfortunately, these techniques are often narrowly delineated for specific field scenarios or species. Many require sophisticated, custom-designed equipment or analytical tools, limiting their applicability. We aimed to devise a photogrammetric technique for accurate volume/mass estimation of seals under a variety of field scenarios without manipulation of the animal and with minimal equipment. We used Photomodeler Pro 3-dimensional modelling software to estimate the mass of 53 weighed southern elephant seals Mirounga leonina. The method is centred on animal volume estimation in relation to the 3-dimensional area around it, rather than features of the animal itself, an approach that liberates limitations associated with earlier studies. No morphometric body measures are required for such volume/mass estimation. We offer predictive equations that allow high confidence in mass estimates relative to measured mass (95% confidence interval of mean deviation from measured mass is from ±1.34 to ±3.83% depending on the field scenario). A single photographer with a measuring stick and non-customised digital photographic equipment can use this technique to determine the mass of an elephant seal anywhere in the field with the push of a button.

【 授权许可】

Unknown