Postmortem interval applied to cetacean carcasses: Observations from laboratory and field studies with the Abrolhos Bank Region, Brazil

• Published in: Forensic Science International: Animals and Environments
• Main Authors: Hernani Gomes da Cunha Ramos, Adriana Castaldo Colosio, Milton César Calzavara Marcondes, Rodrigo Pinho Gomez Lopez, Brittany Ederer Michalski, Renato David Ghisolfi, Maria Isabel Carvalho Gonçalves, Ricardo Siqueira Bovendorp
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2024
• Subjects: Humpback whale; Guiana dolphin; Franciscana dolphin; Decomposition study; Time since death; Chrono-thanatology; Ecology; QH540-549.5; Veterinary medicine; SF600-1100; Humpback Whale
• Online Access: https://doi.org/10.1016/j.fsiae.2024.100082; https://doaj.org/article/48ecfb533c6540e5b72d142618d1eeec

Estimating the postmortem interval (PMI) in cetaceans is challenging. These mammals often sink after death, later floating and traveling considerable distances before stranding, complicating decomposition stage analysis. Our study investigates decomposition patterns in humpback whale, guiana dolphin, and franciscana dolphin. We analyzed decomposition stages using photographic data from Instituto Baleia Jubarte (IBJ) and conducted a controlled guiana dolphin carcass decomposition study in a laboratory to establish a reliable PMI baseline for carcasses found along Brazil's Abrolhos Bank region. Our findings reveal species-specific decomposition timelines: humpback whale carcasses typically beach within 14 days post-death maximum, while franciscana and guiana dolphins strand within seven to eight days. The most common PMI for whales was five to six days, guiana dolphins four days, and franciscana dolphins four to five days. We used the five decomposition codes: I alive animals, II fresh carcass, III moderate decomposition, IV advanced decomposition, V skeletal remains. For small cetaceans, code II indicates a PMI of two days, III four days, and IV seven days. For large whales, code II signifies a PMI of one day, III three days, and IV seven days. PMI estimation is vital for identifying the period a carcass floated from death site to shoreline. This information supports forensic approaches in understanding anthropogenic impacts on cetacean mortality and aids ecological and conservation studies regarding cetacean strandings, using PMI and backtracking techniques.