Age estimation in bowhead whales using tympanic bulla histology and baleen isotopes

• Published in: Marine Mammal Science
• Main Authors: Sensor, Jennifer D., George, John C., Clementz, Mark T., Lovano, Denise M., Waugh, David A., Givens, Geof H., Suydam, Robert, Stimmelmayr, Raphaela, Thewissen, J. G. M.
• Other Authors: Kent State University
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2018
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Arctic; Arctic Population
• Online Access: http://dx.doi.org/10.1111/mms.12476; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fmms.12476; https://onlinelibrary.wiley.com/doi/pdf/10.1111/mms.12476

Abstract Tympanic bullae and baleen plates from bowhead whales of the Western Arctic population were examined. Growth layer groups (GLGs) in the involucrum of the tympanic bone were used to estimate age of the whales, and compared to stable isotope signatures along transects of baleen plates and the involucrum. The involucrum of the tympanic bone consists of three regions that form in utero , during nursing in the first year, and during the first decades of life, respectively. Life history events, such as annual migration, are recorded in the bowhead tympanic bulla. It is likely that bone growth in the bowhead tympanic occurs during periods of high food intake, while slow or arrested growth occurs during periods of low food intake. Comparisons between numbers of GLGs in the tympanic, number of isotopic oscillations in a baleen plate, length of the baleen plate, and total whale length show correlation coefficients as high as 0.97. The tympanic GLG method is particularly useful for estimating the age of whales up to 20 yr old.