The effects of no-take zoning, region and year on reproductive output of the common coral trout, Plectropomus leopardus

No-take marine reserves potentially protect against overfishing by allowing larger, older, and more fecund fish to prosper (Russ 2002, Sale et al.2005). This is because fecundity usually increases exponentially with female size and/ or age (PDT 1990, Cooper et al. 2003). This relationship is well documented for gonochoristic species. For hermaphroditic species, particularly those exploited in tropical reef fisheries, the relationship has received little attention. The common coral trout Plectropomus leopardus, a batch spawning protogynous hermaphrodite, is the major target species in the reef line fishery in the Great Barrier Reef Marine Park (GBRMP), Australia. Fishing has been implicated in reducing the size and age at sex change of P. leopardus (Adams 2002), and significantly higher densities and older and larger females have been reported on reefs closed to fishing (Adams et al. 2000, Evans and Russ 2004, Mapstone et al. 2004). Fecundity can be difficult and time consuming to estimate, and many studies have limited data sets, are based on limited size ranges, and often lack age data. Additionally, few studies have investigated regional and annual variation in fecundity. The objectives of this study were to examine how P. leopardus fecundity varies with fish size and age on the GBR, and to compare P. leopardus fecundity between reefs zoned open and closed to fishing, between 3 GBR regions and over 3 years