TY - JOUR
T1 - Estimating body mass of sperm whales from aerial photographs
AU - Glarou, Maria
AU - Gero, Shane
AU - Frantzis, Alexandros
AU - Brotons, José María
AU - Vivier, Fabien
AU - Alexiadou, Paraskevi
AU - Cerdà, Margalida
AU - Pirotta, Enrico
AU - Christiansen, Fredrik
N1 - Funding: The authors wish to thank Fundación Biodiversidad for supporting COLCA project and all the ecovolunteers involved in the fieldwork of the Balearic Sperm Whale project. They are grateful to OceanCare (Switzerland) for their continuous support of the sperm whale research and conservation activities of the PCRI since 2008 and to Prof. Kostas Kostarelos and the University of Manchester for organizing the crowd-funding project “Nanowhales” to cofund the research expedition of 2019 along the Hellenic Trench. This paper represents HIMB and SOEST contribution nos. 1903 and 11568, respectively. Field research in Dominica was funded through a FNU fellowship for the Danish Council for Independent Researchsupplemented by a Sapere Aude Research Talent Award, a Carlsberg Foundation expedition grant, a grant fromFocused on Nature, and a CRE Grant from the National Geographic Society to S.G.; a FNU Large Frame Grant andVillum Foundation Grant to Peter T. Madsen at Aarhus University; and supplementary grants from the Arizona Cen-ter for Nature Conservation, Quarters For Conservation, the Dansk Akustisks Selskab, Oticon Foundation, and theDansk Tennis Fond.
PY - 2023/1/1
Y1 - 2023/1/1
N2 - Body mass is a fundamental feature of animal physiology. Although sperm whales (Physeter macrocephalus) are the largest toothed predators on earth, body mass is seldom included in studies of their ecophysiology and bioenergetics due to the inherent difficulties of obtaining direct measurements. We used UAV‐photogrammetry to estimate the weight of free‐ranging sperm whales. Aerial photographs (23 calves, 11 juveniles, 55 nonmother adults, 13 mothers) were collected in the Eastern Caribbean and Mediterranean Sea during 2017–2020. Body length, widths, and heights (dorso‐ventral distance at 5% increments) were measured from dorsal and lateral photographs, while body volume was calculated using an elliptical model. Volume varied noticeably (12.01 ± 4.79 m3) in larger animals (>8 m), indicating fluctuations in body condition of adults and mothers. Volume was converted to mass, using tissue‐density estimates from catch data, animal‐borne tags, and body‐tissue composition. Average total body density ranged from 834 to 1,003 kg/m3, while the weight predictions matched with existing measurements and weight‐length relationships. Our body‐mass models can be used to study sperm whale bioenergetics, including inter‐ and intraseasonal variations in body condition, somatic growth, metabolic rates, and cost of reproduction.
AB - Body mass is a fundamental feature of animal physiology. Although sperm whales (Physeter macrocephalus) are the largest toothed predators on earth, body mass is seldom included in studies of their ecophysiology and bioenergetics due to the inherent difficulties of obtaining direct measurements. We used UAV‐photogrammetry to estimate the weight of free‐ranging sperm whales. Aerial photographs (23 calves, 11 juveniles, 55 nonmother adults, 13 mothers) were collected in the Eastern Caribbean and Mediterranean Sea during 2017–2020. Body length, widths, and heights (dorso‐ventral distance at 5% increments) were measured from dorsal and lateral photographs, while body volume was calculated using an elliptical model. Volume varied noticeably (12.01 ± 4.79 m3) in larger animals (>8 m), indicating fluctuations in body condition of adults and mothers. Volume was converted to mass, using tissue‐density estimates from catch data, animal‐borne tags, and body‐tissue composition. Average total body density ranged from 834 to 1,003 kg/m3, while the weight predictions matched with existing measurements and weight‐length relationships. Our body‐mass models can be used to study sperm whale bioenergetics, including inter‐ and intraseasonal variations in body condition, somatic growth, metabolic rates, and cost of reproduction.
KW - Body condition
KW - Marine mammal
KW - Morphometrics
KW - Odontocete
KW - Physeter macrocephalus
KW - Unmanned aerial vehicle
U2 - 10.1111/mms.12982
DO - 10.1111/mms.12982
M3 - Article
SN - 0824-0469
VL - 39
SP - 251
EP - 273
JO - Marine Mammal Science
JF - Marine Mammal Science
IS - 1
ER -
