Abstract: Accurately determining the age of belugas (Delphinapterus leucas) has been difficult and the source of considerable uncertainty in demographic studies of this species. Previous studies have predominantly assumed that two growth layer groups (GLGs) are deposited annually in beluga teeth; however, recent evidence from aquarium-raised individuals and radiocarbon dating assays of teeth lends support to the hypothesis that one dentinal GLG is deposited annually in beluga, rather than to the competing hypothesis claiming the rate is twice as large. We present the allometric relationship between female age and length at maturity among delphinoid cetaceans and suggest that estimates of beluga age at maturity based on one GLG per annum are in better agreement with this relationship than estimates based on the competing hypothesis. Our results, and a reanalysis of previously published evidence, give further support to the one annual GLG hypothesis; however, a change in the pattern of deposition rate at sexual maturity remains a possibility, and research is needed to determine whether changes in dentine deposition rates during life stages of beluga.
Key Words: LIFE HISTORY; DEMOGRAPHY; GROWTH LAYER GROUPS; BELUGA; DELPHINAPTERUS LEUCAS
Document Type: Research article
Page Numbers: 241 - 245