Spatial and inter-annual changes in the growth patterns of young-of-year anchovy in a high productive ecosystem

The spatial and temporal variation of the early growth patterns (EGP) of anchoveta (Engraulis ringens), were analyzed and compared among three geographic areas, i.e., Northern zone (18–24°S); North-central zone (26–30°S) and Southern zone (33–42°S) off the Chilean coast over three years (i.e., 2015, 2016 and 2019). EGP were determined through otolith microstructure analysis for juveniles ranging from 2.0 to 12.0 cm in total length (TL), corresponding to ages from 28 to 187 days. The comparative growth analysis between the three study areas for the 2015, 2016 and 2019 cohorts showed significant differences in the Laird-Gompertz growth parameters and the absolute growth rate at the inflection point (0.67–1.11 mmd⁻¹). A generalized additive models (GAM) was used to analyze changes in mean daily increment width profiles (IW) as related to the area, monthly cohort, sea surface temperature (SST) and Chlorophyll concentration (Chloa) as predictive variables. The GAM did not show significant difference in mean IW between northern and north-central areas (7.9 ± 3.9 vs 8.3 ± μm), although they significantly varied with respect the southern area, where the lower values of IW were found (5.6 µm). The GAM showed higher IW partial residuals when SST was above 14 °C and Chloa concentration was lower than 2 m gm⁻³. Overall results showed a high plasticity in the early growth pattern of E. ringens, indicating interannual and spatial variability, with SST playing a pivotal role across a wide latitudinal gradient off Chilean coast.