Abstract
Sexual maturation with age was analyzed for arrow squids Nototodarus gouldi and N. sloanii in New Zealand waters. A total of 654 specimens of N. gouldi and 771 specimens of N. sloanii were aged successfully using the statolith micro-structure. Based on the results of ageing, the relationships between age and some gonadsomatic indices were analyzed. The maturation patterns of both species are similar to each other, though the sample number of mature N. sloanii is not sufficient. The change of gonad somatic indices suggests that males start to mature from around 200 days old. Testis somatic index (TSI) reaches a maximum at about 270 days. Females start to mature at the time when TSI reaches the maximum in males. The development of ovary, oviduct, and Nidamental gland occurs simultaneously, and copulation also occurs at the same period. It is suggested that spawning may occur within two months after copulation, considering the period of copulation and a single year life span of arrow squids.
