Dear colleagues, My co-authors and I are happy to announce the publication of the following paper in Marine Mammal Science: Glarou, M., Gero, S., Frantzis, A., Brotons, J. M., Vivier, F., Alexiadou, P., Cerdà, M., Pirotta, E., & Christiansen, F. (2022). Estimating body mass of sperm whales from aerial photographs. Marine Mammal Science, 1–23. Abstract: 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. The paper is open-access and can be accessed from the following link: https://onlinelibrary.wiley.com/doi/full/10.1111/mms.12982 Best regards, Maria Glarou PhD Fellow Húsavík Research Centre University of Iceland Hafnarstétt 3, 640 Húsavík Email: mag133@hi.is<mailto:mag133@hi.is> / maria_glarou@outlook.com<mailto:maria_glarou@outlook.com> Skype: mariag.23 Mobile: +30 698 5689823 / +45 50174014 Twitter: @mglarou<https://twitter.com/mglarou> ResearchGate<https://www.researchgate.net/profile/Maria-Glarou> / Google Scholar<https://scholar.google.com/citations?user=gVV1c04AAAAJ&hl=en>