Age, Growth and Maturation of Largehead Hairtail (Trichiurus japonicus) in the East China Sea

Largehead hairtail(Trichiurus japonicus)is a commercially important fish species in China Seas,characterized by wide distribution,seasonal migration,spawning all year round.Under long-term high fishing pressure,the biological traits of largehead hair-tail have changed,such as miniaturization,smaller size-at-age and earlier age-at-maturation.To explore its current biological charac-ters,we analyzed age,growth and maturation of largehead hairtail in the East China Sea by analyzing the otolith microstructure and gonads.The results showed that largehead hairtail is mainly composed of 1 year and 2 years old individuals.The estimated von Ber-talanffy growth function(VBGF)showed significant differences between sexes,and asymptotic pre-anal length of male is longer than that of female.Two spawning seasons were observed in spring and autumn by monthly gonadosomatic index(GSI).Compared to historic survey data,the average pre-anal length at age decreased and size-at-maturation became smaller in the East China Sea.This study updates life history parameters of largehead hairtail,and provides a reference for the present status of largehead hairtail,which can contribute to largehead haritail stock assessment and sustainable utilization in the China Seas.