Estimation of Age,Growth and Maturation of Purpleback Flying Squid,Sthenoteuthis oualaniensis,in Bashi Channel,Central Pacific Ocean

The age, growth and maturation of Sthenoteuthis oualaniensis were determined with statolith data collected with a light purse seine from the Bashi Channel of central Pacific Ocean. The estimated longevity of the squid was no more than 6 months for females, and no more than 5 months for males. Growth in mantle length（ML） was best described by logistic models for both females and males, while growth in body weight（BW） was best fitted by power curves. The maximum absolute growth rate（AGR） and instantaneous growth rate（IGR） in ML or BW both occurred at 91–105 days for females and 76–90 days for males. Back calculated hatching dates were from October to January, with a peak in December, although the short duration of sampling date might have had an influence on the result. The lower percentage of mature females（37.2%） suggested that the study area during the sampling date was not a spawning ground for the species. Size and age at first maturity were 183 mm ML and 136 days for females, whereas they were 156 mm ML and 85 days for males.