Age estimation of white whales (Delphinapterus leucas) from Greenland

Abstract

Various techniques of displaying growth layer groups (GLGs) in teeth from white whales, Delphinapterus leucas, from Greenland were tested. The dentine and cementum in unprepared longitudinal thick sections (150-200μm) displayed under transmitted polarized light microscope generally provided the simplest and clearest display of GLGs. Teeth taken from the lower jaw of white whales in West Greenland show significant wear at a much earlier age than teeth of white whales from northern Quebec, the White Sea and the Kara Sea. The least worn teeth are usually positioned towards the rear of the lower jaw (tooth numbers 7-9). They give the highest number of GLGs and thus most accurately reflect the age of the whale. Teeth from one white whale that was captured when approximately three years old and maintained in captivity for 15 years showed 30-36 GLGs. This finding adds to the evidence that two GLGs are deposited annually in the teeth of white whales.