1. This paper sets out to: (1) review previous ecological studies and analyse recent trends of the Peruvian bay scallop fishery in order to better understand and to model the species' temporal and spatial (meta) population dynamics along the South Pacific coast; (2) develop a fisheries model to protect the stock from overexploitation and optimize the annual yield of the pulse fishery in Independence Bay, the centre of the scallop diving fishery in Peru. 2. Natural stock fluctuations are very pronounced in this species and are positively correlated with the El Nino-Southern Oscillation (ENSO). During such an event, habitat conditions for the Peruvian bay scallop are improved either regionally or locally, such that populations proliferate and larval production and dispersal are greatly increased. Extinct beds and new habitats are recolonized during these periods (producing a strong pulse of metapopulation biomass), although most become extinct very shortly thereafter. 3. For management purposes, two considerations are fundamental: (1) heavy overfishing or extinction of the main scallop source populations would endanger the metapopulation as a whole; (2) rates of growth and survival greatly increase (and with them the potential yield of the scallop stock) locally over an El Nino cycle in a way that can be roughly estimated from past experience, including the most recent Fl Nino event (1997-1998). 4. We suggest a fisheries management regime capable of adapting to natural changes and propose a procedure for calculating both the optimal yield and the respective fishing effort under normal upwelling and El Nino scenarios, considering changes in the size at first capture (Lc) and fishery mortality (F). Copyright (C) 3000 John Wiley & Sons, Ltd.
