Study on the foundational biological character of Octopus tankahkeei

A total of 408 specimens of Octopus tankahkeei were collected from the fishery in Xiangshan Bay,Zhejiang province between January 2003 and December 2003.The animals were grouped by sex,size and month for length frequency analysis,annual changes rhythmon biological indexes and major traits of body shape were examined.The results show:the monthly distributions of length frequency change greatly,which is wider in June and July than the others months,while there are two peaks in June(240 mm and 360mm,the percentage is 13.3% and 16.7% separately).The animals grow slowly in winter,while the rapid growth period occurred in March and April,juvenile octopus could be found in June and July after nearly 40 days hatching from spawning.There were significant differences between the individual indexes, such as TL/D_L,TL/D_K,and TL/V,of female and male by the statistics;there were significant differences in the D_L,D_K and Volume,which is larger of female's than that of maleps when the total length is equal.Additionally,the females are more width and embonpointthan males in body shape.