Variability of sardine catch as related to enrichment, concentration, and retention processes in the central Gulf of California

The sardine (Sardinops sagax) fishery of the Gulf of California is among Me xico's most important fisheries, accounting for the largest catch and provi ding many productive jobs. During the early 1990s, this fishery collapsed t o less than 3% of the production maximum. Surprisingly, after two years of very low catch the fishery recovered quickly. We propose that these large f luctuations may be explained mainly by physical processes (enrichment, rete ntion, and concentration) governing the sardine spawning habitat. The spawn ing area may be influenced by processes such as tidal mixing, winter northw esterly winds, coastal upwelling, prevailing surface currents, and Ekman tr ansport, but most of its variability is believed to be wind-forced. Therefo re we attempted to relate spawning extension to wind variations. By fitting an equation that expresses spawning as a probability function of a wind-de rived index, we have built a spawning-probability time series based on egg and larval survey data and then tested against an independent series of lan dings and biomass indices (number of recruits and adults). Results show coh erent relations between the spawning-probability series and the biological and fisheries data, despite large fluctuations (collapse and recovery). Our results are encouraging and may provide a solid theoretical basis for futu re environment-monitoring systems for the sardine fishery in the gulf.