Red Seabream is a valuable fish resource for ports in Southern Spain. It is critical that this fishery be well managed to ensure a sustainable and viable commercial fishery into the future, which recent fishing regulations should accomplish. Fish stocks appear to be increasing. We use Data Envelopment Analysis and Stochastic Frontier Analysis techniques to estimate the impact of recovering fish stocks on fishing output. Since imposed fishing regulations to protect the fishery essentially have halted technological progress in the fleet, we alter the standard Malmquist decomposition of efficiency and technological change instead into efficiency and the impact of fishing stock change. We find that over the 3 year period of 1999 through 2001, increase in fishing stocks lead to a 2.05 annual percent increase in fishing output by DEA computations, and 2.70 annual percent increase by SFA computations