Stock Assessment of Common Coral Trout (Plectromomus leopardus) in Queensland

Abstract

Queensland’s common coral trout (Plectropomus leopardus), a species of grouper, is a line caught fish forming a single population (stock) across the Great Barrier Reef (GBR). Common coral trout are protogynous hermaphrodites (born female, many later changing sex to male) and aggregate to spawn during spring and summer. They can grow to 5 kg and 18 years of age. The stock extends north from the GBR into the eastern Torres Strait where it is under Commonwealth jurisdiction.
This assessment builds on previous assessments published in 2014 and 2019 and includes updates to the input data and methods. This stock assessment used a length-and-age structured population model with a yearly time step. The model contained two sub-populations: a sub-population associated with reefs in the Great Barrier Reef that remained open to fishing after the introduction of the Representative Areas Program in 2004, and a sub-population, associated with reefs that have been closed to fishing since the introduction of the Representative Areas Program.
Model results suggested that biomass declined between 1953 and 2011 to 51% unfished biomass. In 2020, the stock level was estimated to be 59% unfished biomass.
The recommended biological harvest in calendar year 2020 to achieve the Sustainable Fisheries Strategy longer term target of 60% unfished biomass is 1034t (420–1258 range across models).