The workshop report lists a number of conclusions, including the acceptance of one Growth Layer Group (GLG) deposition annually in beluga teeth. Recommendations include suitable methods of aging for monodontids, including dentine GLG in beluga, aspartic acid racemisation (AAR) of eye lens nucleus in narwhal, and monitoring free-living belugas for later validation of longevity and reproductive age parameters. The use of reference collections of beluga teeth and tooth images, especially for known-age and -history animals, for standardisation of GLG counting within and among laboratories is essential, and frequent testing of accuracy and precision in GLG counting is important for maintaining standards.