Evolution of age determination methods for three tuna species

The age-based stock assessment model is the primary model used in current research on tuna stock assessment. The accuracy of age identification has a direct impact on the development of the stock assessment models. The specific application of age-identification methods for tuna varies widely across species, oceans, and historical periods, however, most methods use hard parts to infer age. There is currently no research on the development and evolution of tuna age-identification methods. Based on literature review, we used the Multinomial Logistic Regression (MLR) model to examine the differences of tuna age identification methods across species, oceans, and historical periods. We found that otoliths and dorsal fin spines analyses were most commonly used in the Pacific Ocean and the Indian Ocean than the Atlantic Ocean. Compared to albacore tuna Thunnus alalunga））, otoliths analysis was more frequently used to age bigeye tuna Thunnus obesus and yellowfin tuna Thunnus albacores））. As aging procedures advanced, fin spines and otoliths became the main aging materials. It is recommended that age and growth studies in the Indian Ocean should be intensified, especially for albacore tuna.