Seasonal patterns in the distribution of Engraulis anchoita in the North Patagonian Continental Shelf of Southwestern Atlantic Ocean

The Patagonian stock of the anchovy Engraulis anchoita is distributed between 41° and 47°30’S over the Argentinian Shelf. This is an underexploited species that plays a key role in the North Patagonian ecosystem (Southwestern Atlantic Ocean) since it constitutes the food of numerous species of fish, birds, and marine mammals. Knowing the spatial and seasonal dynamics of the abundance of this species is a valuable source of information for understanding how it could affect the functioning of this ecosystem. To this end, the effect of oceanographical variables on the presence/absence and relative abundance of the Patagonian anchovy were analyzed in 2 seasons over a 10 yr period. A mixed effect of the oceanographic variables and the relative abundance in warm and cold seasons was found, as well as differences in abundance and presence of this species when comparing consecutive seasons. The spatial evolution of the distribution of the Patagonian anchovy shows a contraction/expansion pattern. It contracts towards the northern area and towards lower latitudes during cold seasons (up to 45°30’S) and then disperses to occupy the entire studied area during warm seasons, reaching 47°30’S. Knowing the spatial and seasonal dynamics of small pelagic fish is valuable for achieving sustainable management of different resources within the framework of an ecosystem approach.