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19589
Open
SC/68D/SM/04
Photo-identification-based Age Estimation of False Killer Whales Utilizing Information on Sex, Relative Size, Markings, and Morphology
Michaela A. Kratofil, Sabre D. Mahaffy and Robin W. Baird
IWC
Age is a critical metric for understanding the dynamics of wildlife populations. However, estimating the age of individuals in wild populations is challenging; while methods are available for aging dead animals (e.g., tooth sectioning), obtaining reasonably accurate age estimates of live, free-ranging animals is much more difficult. This is especially the case for cetaceans that move over large ranges, have an unpredictable occurrence, or may be cryptic in nature. We developed a protocol for deriving age estimates of false killer whales (Pseudorca crassidens) in Hawaiian waters using information curated from a long-term photo-identification catalog. The protocol integrates several qualitative lines of evidence (e.g., morphometric features, parentage, markings) into a quantitative framework for deriving age point estimates. Further, confidence ratings based on the strength and weaknesses of supporting evidence were developed to directly account for uncertainty in age estimates and scale the plausible range of ages (minimum and maximum) specific to each individual. While originally intended to inform a concurrent study on epigenetic aging of this population, our protocol provides a compelling alternative for estimating the age of individuals with common metrics from photo-identification catalogs and for which advanced genetic aging methods of biological samples (e.g., biopsies) are not feasible.
