Age and growth of the whale shark (Rhincodon typus) in the north-western Pacific

This study estimated age and growth of the largest extant fish, the whale shark (Rhincodon typus) by counting vertebral band pairs from 92 specimens comprising 43 males (2.68-9.88m total length [TL]), 30 females (1.60-7.02m TL), and 19 unsexed individuals (2.83-6.67m TL) taken by Taiwanese commercial fisheries during 2001-06. Growth band pairs up to 25 and 42 were counted for a 6.38-m TL female and a 9.88-m TL male, respectively. Using marginal increment ratio and centrum edge analysis, band pairs were postulated to be formed twice a year. The two-parameter von Bertalanffy growth function provided the best fit without significant differences between sexes. Growth parameters were calculated for both sexes as L=16.80m TL, k=0.037 year(-1); annual band pair formation would modify these parameters to L=15.34m TL, k=0.021 year(-1). Using data reported in another study for 50% size at maturity for males (8.1m TL), and the largest immature and smallest mature females (8.7 and 9.6m TL, respectively) in the Indo-Pacific, these TLs converted to ages at maturity of 17 years for males and 19-22 years for females. The longevity was calculated to be 80.4 years.