Stock discrimination of Atlantic walrus (Odobenus rosmarus rosmarus) in the eastern Canadian Arctic using lead isotope and element signatures in teeth

Atlantic walrus (Odobenus rosmarus rosmarus) harvested from three regions o f the Canadian Arctic, and by different communities within two of those reg ions, were distinguished using the stable Pb isotope or trace element compo sition of their tooth cementum. Walrus from Fore Basin (Igloolik, Hall Beac h), the High Arctic (Grise Fiord, Resolute Bay), and eastern Hudson Bay (Ak ulivik, Inukjuak) were each characterized by specific combinations of Pb is otope ratios and Co concentrations, and we conclude that they represent dif ferent regional stocks. Walrus landed at Akulivik and Inukjuak were further discriminated by significant differences in Pb-208/Pb-207, even though the communities are only 250 km apart. There was more overlap between walrus f rom Igloolik and Hall Beach, which are 80 km apart, but significant differe nces between sites in Pb isotope ratios and in concentrations of V, Zn, and Mo suggested that more than one Fore Basin stock was being harvested, part icularly at Hall Beach, the herds contained a few individuals with isotope ratios significantly different from the rest of the population. These "outl iers" may represent either immigrants from other geological provinces or an imals caught in other areas. Further investigation of the outliers could pr ovide information regarding hunting patterns, walrus home ranges, and the r ates and demographics of interstock migrations.