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Age and growth estimates of the blue shark, Prionace glauca, in the central South Pacific Ocean
The age and growth of the blue shark, Prionace glauca, in the central South Pacific were described based on 267 specimens, that were collected by scientific observers on-board Taiwanese large-scale tuna longline fleets between May 2009 and May 2011. Growth band pairs (identified as translucent and opaque bands) were counted on images photographed from X-ray films of the vertebrae from the caudal peduncle region. The marginal increment ratio and centrum edge analysis indicated that a growth band pair on vertebral centrum was formed once a year. The band pairs after the birth mark were counted from 2-11 and 2-15 for females and males, respectively. The bias corrected Akaike Information Criterion indicated that the von Bertalanffy growth function (VBGF) best fitted the observed total length (TL)-at-age data. The parameters of sex-specific VBGF were estimated as follows: L = 376.6 ± 32.6 cm TL, k = 0.128 ± 0.022 year-1, and t0 = -1.482 ± 0.54 years for males, and L = 330.4 ± 46.6 cm TL, k = 0.164 ± 0.057 year-1, and t0 = -1.294 ± 0.78 years. The longevities were estimated to be at least 16.8 and 21.4 yrs for females and males, respectively.
MF17098 Accepted 26 January 2018
© CSIRO 2018