FUTURE HABITAT SUITABILITY OF LITTLE TUNA (Euthynnus affinis) IN THE BANDA SEA UNDER CLIMATE CHANGE SCENARIOS

Abstract

Banda Sea is one of most important fishing grounds for Euthynnus affinis in Indonesia; however, information on its potential habitat distribution and response to climate change remains limited. This study aimed to analyze current potential habitat distribution of E. affinis based on oceanographic conditions and to project future habitat suitability under climate change scenarios for the 2030–2040 period. Habitat suitability was modeled using ‘Maximum Entropy’ (MaxEnt) approach with fish occurrence data collected from 2017 to 2022 and environmental variables including sea surface temperature, chlorophyll-a, sea surface salinity, current velocity, and bathymetry. The model demonstrated good predictive performance, with an Area Under the Curve (AUC) value of 0.794. Sea surface salinity and sea surface temperature were identified as the primary environmental factors influencing the distribution of E. affinis. Optimal habitat conditions were associated with salinity of 33–34 PSU, sea surface temperatures of 30–31 °C, and current velocities of 0.05–0.20 m s⁻¹. Under present environmental conditions, suitable habitats were primarily concentrated in the western, northwestern, and southwestern parts of the Banda Sea. Future projections indicated that the Banda Sea is likely to remain a suitable habitat for E. affinis under all climate change scenarios, although shifts in habitat quality and spatial distribution are expected. Among the projected scenarios, SSP2-4.5 maintained relatively favorable habitat conditions, whereas SSP4-6.0 showed the greatest decline in habitat suitability. These findings provide valuable scientific information to support climate-adaptive fisheries management through the identification of potential future habitats for E. affinis.

Key words: Banda Sea, climate change, Euthynnus affinis, habitat suitability, ‘Maximum Entropy’