An epigenetic clock to estimate the age of living beluga whales

DNA methylation data facilitate the development of accurate molecular estimators chronological age or “epigenetic clocks.” We present a robust epigenetic clock for beluga whale, Delphinapterus leucas, developed an endangered population in Cook Inlet, Alaska, USA. used custom array to measure levels at 37,491 cytosine–guanine sites (CpGs) from skin samples dead whales (n = 67) whose ages were estimated based on tooth growth layer groups. Using these calibration data, penalized regression model selected 23 CpGs, providing R2 0.92 training data; and 0.74 median absolute error 2.9 years leave one out cross-validation. applied independent dataset 38 collected with biopsy dart living between 2016 2018. Age estimates ranged 11 27 years. also report sex correlations CpG describe approach identifying animal using methylation. The presented here have broad applications conservation management Inlet potentially other cetaceans.