TEMPORAL TRACKING OF A STRONG COHORT IN THE POPULATION OF A CORAL-REEF FISH, THE CORAL TROUT, PLECTROPOMUS LEOPARDUS (SERRANIDAE, EPINEPHELINAE), IN THE CENTRAL GREAT-BARRIER-REEF, AUSTRALIA

We document a strong year-class in the population of coral trout (Plec tropomus leopardus) in the central Great Barrier Reef, Australia. From 1990 to 1993 samples of coral trout were collected at two coral reefs closed to fishing since 1987, and at two reefs open to fishing. On th e closed reefs the age structure was dominated by a strong cohort that settled in early 1984 and that accounted for 54, 45, 42, and 36% of t he experimental hook and line catches in 1990 to 1993, respectively. A similar strong cohort was not obvious on the fished reefs close by, p ossibly owing to small sample sizes. This is the first time a dominant age-class has been tracked over time for any coral reef fish by exami nation of age structures. The results demonstrate that strong interann ual fluctuations in recruitment can affect the local abundance of cora l trout populations substantially and that strong recruitment events c an be retained in the age structure of coral trout populations. Furthe rmore, because age of recruitment to the fishery is approximately 3 ye ars, these results suggest the possibility that recruitment strength m ay be predicted up to 3 years in advance using yearly surveys of juven ile fish.