Fishery biology of arrow squids, Nototodarus gouldi and N. sloanii, in New Zealand waters

The arrow squid stock in New Zealand waters, consisting of Nototodarus gouldi and N. sloanii, is one of the important squid resource for the Japanese squid fishery. The present study revealed some biological characteristics of the two species such as growth, maturation, migration, and annual variation of abundance based on the statistics of the Japanese squid fisheries and biological data of squid collected by the various research activities. The results of ageing based on daily increment counts show that spawning occurs throughout the year. The both species are distributed mainly on the shelf throughout their life span with some inshore-offshore migration with age, but they do not migrate on large scale. The analysis of CPUE for each month class shows the seasonal cohorts in each area fluctuate independently. This phenomenon points out that the small-scale environmental factors may be relatively important for the fluctuation of each cohort. The main target of management for a fishery on annual squid is to allow enough spawners to escape. Considering the characteristics of arrow squid, effort regulation is the best way to manage the fishery. At the present situation, the regulation on rough scale regardless the fishing areas may be the most practical way under the existence of self regulation characteristics if the fishery which tends to target most abundant cohort