Growth, Age Estimation and Preliminary Estimates of Longevity and Mortality in the Moses Perch, Lutjanus russelli (Indian Ocean form), from Continental Shelf Waters off North-Western Australia

摘要

Moses perch, Lutjanus russelli were sampled in continental shelf waters off the Pilbara coast of North-Western Australia from July 1997 to September 1999 Ages were determined by examining the thin transverse sections of their sagittal otoliths and were based on counts of alternating opaque and translucent zones (annual growth increments). Otolith length and breadth (width) increased linearly with fish length, whereas otolith weight was strongly correlated with fish age. The continuous growth of the otoliths provides additional evidence that the opaque and translucent zones used to estimate age in this study are formed on a yearly basis Growth was rapid during the first 5 years of life, after which growth in length was much reduced. No significant differential growth between the sexes was evident in observed length-at-age Parameters of the von Bertalanffy growth curve (fork length-at-age) were L∞ = 330.1, K = 0.347 and t_0 = -0.27 Preliminary estimates of longevity between sexes were similar with amaximum observed age of 21 years for male and 20 years for female. The preliminary estimate of the annual instantaneous rate of natural mortality (M) was 0 152. The life history characteristics of L. russelli indicate that this species is potentially vulnerable to oveifishing despite its small size. The existing fisheries management arrangements and control mechanisms within the trap, line and trawl fisheries of Notth-Western Australia are likely to maintain adequate levels of the spawning stock biomass of these fish as long as each fishing sector does not expand beyond current boundaries.