Age determination of minke whales (Balaenoptera acutorostrata) using the aspartic acid racemization technique

Eyeballs were collected from 31 female minke whales caught in the North Sea, Norwegian Sea and Barents Sea. The eye-lens nucleus was dissected Out and the relative amount of D- and L- enantiomers of aspartic acid measured using high-performance liquid chromatography (HPLC). A racemization reaction changes the D/L aspartic acid relationship in the nucleus over time. The age of each whale was estimated using the racemization rate for fin whales along, with the measured D/L ratio. The minimum age estimated was 0 years, while the maximum was 32 years. The SE of the age estimates ranged from 4.5 to 8.7 years. Age at sexual maturity was estimated to 5.8 (+/-3.0) years by regressing the number of ovulations versus the ago estimate. Using the von Bertalanffy growth model, age at sexual maturity was estimated to 7.8 (+/-6.0) years, and age at physical maturity to 13 years. These estimates are consistent age estimates were detected, with other demographic data for the species. No systematic errors in the a but the racemization rate (2k(ASP)) and initial ratio of D/L should be estimated specifically for minke whales to ensure accurate age estimates using this technique.