Demography of a large grouper, Epinephelus fuscoguttatus, from Australia's Great Barrier Reef: implications for fishery management

Epinephelus fuscoguttatus is widespread throughout the Indo-Pacific and features strongly in regional fisheries, including the live reef fish trade. We investigated age-specific demographic and reproductive characteristics of E. fuscoguttatus from the Great Barrier Reef, Australia, and examined implications for resource management. Age, growth, longevity, and the relationships between size or age and female sexual maturity and the recruitment of males into the study population were examined. Age validation using both oxytetracycline marking and edge-type analysis demonstrated that a single annulus formed each year. This grouper is long-lived (>40 yr) and relatively slow-growing. The size and age distributions of the sexes strongly suggested protogynous hermaphroditism. Histological data suggested infrequent spawning in small mature females. Females contribute very little to reproductive output until about 566 mm fork length and 9 yr of age. Larger females make important reproductive contributions during their 30+ yr reproductive lifespan. Their relatively long lifespan, restriction of males to large size groups, and the disproportionate contribution of large females to reproduction have important implications for the harvest of E. fuscoguttatus. For example, current Queensland size regulations are poorly matched to the species' biology because they do not protect the reproductive elements of populations. © Inter-Research 2006.