This paper estimates a structural model of multiple-species harvesting costs in the eastern Gulf of Mexico reef fish fishery. The calibrated model is used to predict fleet size, vessel-level harvesting activity and fleet-wide revenues and costs that are expected under a proposed individual fishing quota (IFQ) management program for grouper species. Results suggest that significant fleet downsizing, scale economies and pure efficiency gains will emerge under IFQs. Overall, IFQs appear to be an attractive alternative to the current controlled access management program in the fishery.