Growth and mortality of tarakihi (Pisces: Cheilodactylidae) in lightly exploited populations

Abstract

Abstract The lightly exploited populations of tarakihi Cheilodactylus macropterus off the west coast of the South Island and off the Chatham Islands were sampled for age and growth in 1971 and 1972. The lengths‐at‐capture showed similar growth curves in both areas, a major feature being a rapid decline in annual length increment after year 10 (mean length at that age is 38–39 cm). Both populations contained a large proportion of fish older than 10 y. A rapid decline in annual length increment after year 10 has not been observed in the heavily fished tarakihi stock off East Cape and may be characteristic of lightly exploited populations. The age composition of the Chatham Islands tarakihi indicated that this stock has been subject to fluctuations in recruitment and that M was of the order of 0.08. In the lightly fished stock off the west coast of the South Island, Z was approximately 0.13 so F was there possibly of the order of 0.05 (Z, F, and M are the instantaneous rates of total, fishing, and natural mortality respectively).