Growth rate and population structure of snapper,Chrysophrys auratus, in the East Cape region, New Zealand

Abstract

Although Hawke Bay is the south‐eastern limit of the commercial range of the New Zealand snapper, Chrysophrys auratus (Forster), Gisborne and Napier trawlers take significant quantities of this species from grounds between the eastern Bay of Plenty and Hawke Bay. Growth rate is appreciably faster in the East Cape region than in the Hauraki Gulf, and is apparently without local variations. At least one nursery ground occurs in the area, inside 50 m depth. The largest adults occur furthest off shore, and also towards the south of the area; they may represent an accumulation of older fish which have come from more northern regions. The population age structure shows a preponderance of fish over 10 years old; there is considerable variation in year‐class strength. Total mortality rate is apparently low. As continued fishing reduces the numbers of old fish there will be a change in the fishery towards smaller fish, and the annual catch weight might decline. The relative importance of local and immigrant snapper from more northern areas remains unknown.