On the existence of Pacific sardine groups off the west coast of Baja California and southern California

Three possible Pacific sardine groups were detected using monthly catch and sea surface temperature (SST) data from landing ports of Magdalena Bay, Cedros Island, and Ensenada in México, and San Pedro in the United States. With the use of temperature-at-catch criteria, the groups were clearly defined by monthly periods when maximum catches were observed and at specific intervals of SST: one at temperatures above 22°C, one between 17° and 22°C, and a third below 17°C. Assuming that the observed patterns are indicative of sardine stock structure, this method also serves as a practical approach to partitioning and attributing the catch data of each fishing zone to each sardine group, thus improving estimates of population abundance from stock-assessment models. A conceptual model of time-space distribution is proposed to describe the occurrence of Pacific sardine along the west coast of Baja California and southern California. This model mainly explains the seasons of higher abundance of the resource in the different fishing areas.