Climate refugia in a warming ocean: salinity and temperature shape the persistent core habitat of Sthenoteuthis oualaniensis in the Indian Ocean

Global climate change is transforming the marine environment at an unprecedented pace and scale. This study evaluates the impacts of climate change on biodiversity and fisheries resources in the Indian Ocean—a sensitive climatic hotspot—using the purpleback flying squid ( Sthenoteuthis oualaniensis ) as a model species. We systematically projected the current and future patterns of habitat suitability for this species using species distribution models (SDMs). The study aimed to pinpoint key vulnerable areas and potential climate refugia, thereby providing a scientific basis for adaptive management of squid resources, optimized fisheries policies, and science-based delineation of fishing grounds. The results indicate that salinity and temperature are the primary environmental factors governing the spatial distribution of S. oualaniensis . Currently, its suitable habitat is predominantly concentrated in the northwestern Indian Ocean between the equator and 20°N. Model projections suggest that by the 2100 s, some isolated habitat patches in the central and southern Indian Ocean will degrade or disappear. In contrast, the Arabian Sea and the Bay of Bengal exhibit strong spatial stability and are projected to persist as the core distribution area (suitable under both current and future climates) and primary climate refugia for this species. The core stable habitats identified in this study not only inform the scientific foundation for the dynamic adjustment of future fishing grounds but also represent key areas for resource assessment and long-term population monitoring, thus offering crucial insights for developing targeted conservation policies.