Beyond the Boundaries: Poleward Range Expansion of the Atlantic Chub Mackerel Scomber colias in SW Atlantic Ocean

Shifts in species distribution have far-reaching implications across ecological, economic, and social dimensions. Pelagic fish, integral to global fisheries, have displayed notable euryhaline and eurythermal characteristics. However, a poleward range expansion trend has emerged in the northern hemisphere for certain Scomber species since the 2010s, attributed to sea surface temperature and food resource dynamics. Scomber colias, a principal pelagic fishery resource in Argentina, stands as an underexploited species with recent landings totaling approximately 14,800 tons. In the North Patagonian shelf waters, where S. colias resides at its southern distribution, there has been documented ocean warming. In this context, this study evaluates potential changes in the distribution and abundance of S. colias from 1991 to 2022 in the Southwestern Atlantic Ocean (SAO). Drawing on two distinct data sources, the analysis reveals a poleward range expansion, extending to 48°5′S, exceeding historical limits by 278 km. This expansion is positively correlated with rising sea surface temperatures, with the most significant displacement observed during summer, when this species has a high feeding activity in the study area. The investigation further explores the relationship between S. colias presence and the abundance of its primary prey species between 2011 and 2022. This is highly possible, yet no significant results were uncovered. This study marks the first documented southward range expansion of S. colias in the SAO, providing essential quantitative insights for biological studies, fisheries management, and the canning manufacturing industry. The latter could benefit from year-round access to fish, potentially generating employment opportunities and fostering economic growth within the local community.