Modeling the potential distribution of Argentine shortfin squid in the southwest Atlantic Ocean

The Argentine shortfin squid Illex argentinus is an economically important short-lived species widely distributed in the southwest Atlantic Ocean. The abundance and distribution of I. argentinus are associated with climate change and environmental fluctuations. The potential distribution of I. argentinus was modeled with various environmental variables including sea surface temperature (SST), sea surface height (SSH), chlorophyll a, sea surface salinity (SSS), net primary productivity (NPP), mixed layer depth (MLD), eddy kinetic energy (EKE), and photosynthetically active radiation (PAR) using the maximum entropy (MaxEnt) approach during the peak fishing seasons (January–April). The habitat suitability index (HSI) was defined as the probability of species emergence from the MaxEnt model and the area of HSI≥0.6 was regarded as suitable. Results indicate that the predicted habitat correlated with the actual fishing position, with similar trends in the percentages of suitable habitats and catch per unit effort (CPUE) of I. argentinus from January to April. Moreover, SST, SSH, PAR, and MLD were identified critical environmental variables for the distribution of I. argentinus. In addition, the median of preferred ranges of the critical environmental variables were concentrated within the suitable habitats of I. argentinus. The Area under the Receiver Operating Characteristic Curve (AUC) was greater than 0.96 for all four months. Variations in latitudinal and longitudinal gravity centers (LATG and LONG) of fishing effort were consistent with latitudinal and longitudinal gravity centers (LATG_H and LONG_H) of the HSI. Our findings suggest that the MaxEnt model is an effective tool to predict the potential distribution of I. argentinus. Meanwhile, SST, SSH, PAR, and MLD should be given with more extensive attention in predicting the potential distribution of I. argentinus, as they are important environmental indicators that can help decision-makers search for the fishing ground of I. argentinus in the Southwest Atlantic.