Oceanographic Condition of the Habitat and Distribution of Atlantic Chub Mackerel Scomber colias (Actinopteri: Scombridae) in Southwestern Atlantic

The Atlantic chub mackerel, Scomber colias Gmelin, 1789, is a pelagic species, found in schools throughout the Atlantic Ocean. The objective of the present study is to identify the relationship between oceanographic conditions and catches of the Atlantic chub mackerel fishing resource in the Southwest Atlantic Ocean (21°S–29°S). The generalized additive model (GAM) was used to determine the influence of oceanographic variables on the catch per unit effort (CPUE) of S. colias. Fishing for Atlantic chub mackerel by the purse seine fleet in the Southwest Atlantic is irregular and is related to resource availability. From 2007 onward, the fleet expanded its operating area, which may have increased the CPUE between 2008 and 2012. GAM model results showed that sea surface temperature (SST) had a nonlinear effect on CPUE, peaking between 24°C and 26°C. Chlorophyll-a also influenced CPUE; however, its effect was weaker, with higher CPUE values linked to lower chlorophyll-a concentrations. The Oceanic Niño Index (ONI) exhibited a nonlinear effect, with both El Niño and La Niña periods associated with lower CPUE than during neutral conditions.