Spatio-temporal feeding patterns of the Atlantic chub mackerel (Scomber colias) in a Southwest Atlantic coastal marine ecosystem (39–42°S)

Abstract

Small- to medium-sized pelagic fish like the Atlantic chub mackerel (Scomber colias) are key trophic connectors in marine ecosystems and a valuable fishery resource. In the Argentine Continental Shelf, two stocks are recognized, but little is known about the southern stock inhabiting the El Rinc´on (ER) coastal ecosystem (39–42◦S). This study presents the first quantitative analysis of the spatio-temporal feeding patterns of S. colias in this region, based on stomach content analysis. We quantified diet composition, feeding intensity, and trophic level, and assessed the influence of body size and reproductive stage. The diet was predominantly zooplanktivorous, with copepods (mainly Calanidae) as dominant prey, supplemented by hyperiid amphipods. Diet composition and feeding intensity varied seasonally and spatially, in line with regional patterns of zooplankton abundance and quality. Higher feeding activity and consumption of large copepods and amphipods occurred in late spring in stratified mid-shelf waters, whereas low feeding levels were recorded in winter in coastal zones. Size-related dietary shifts were evident: larger individuals consumed greater quantities of prey, including larger zooplankton such as Themisto gaudichaudii, likely using particulate feeding. Findings may suggest the existence of two distinct seasonal habitats: a wintering ground with reduced metabolic and foraging activity, and a feeding ground associated with high zooplankton biomass, implying possible movements of schools. The proposed feeding strategies underscore the species’ capacity to maximize resource use and foraging efficiency. This study enhances understanding of the trophic ecology of S. colias and provides a baseline for future research and ecosystem-based fisheries management.