Evaluating the potential impacts of mesoscale eddies on the distribution and abundance of an environmentally sensitive squid species (Sthenoteuthis oualaniensis) in the Arabian Sea.

The purpleback flying squid (Sthenoteuthis oualaniensis) is widely distributed in the Arabian Sea and highly sensitive to environmental changes. Mesoscale eddies largely occur in the Arabian Sea, playing a significant role in regional biogeochemical processes. However, the impact of eddies on squid abundance is not well studied. Therefore, mesoscale eddies impacts on abundance and spatial distribution of S. oualaniensis were investigated in this study. The results indicated that the monthly catch-per-unit-effort (CPUE) of S. oualaniensis correlated with the variation in the number of eddies, and CPUE within cyclonic eddies (CE) was higher than that within anticyclonic eddies (AE). Sea surface temperature (SST), chlorophyll-a concentration (Chl-a), and dissolved oxygen at 150 m (DO150m) strongly affected the abundance of S. oualaniensis, showing distinct spatial distributions within CEs and AEs. These three key environmental factors were used to construct a habitat suitability index (HSI) model to evaluate the habitat distribution characteristics of S. oualaniensis within CEs and AEs, and results demonstrated CEs were more suitable. Within CEs, suitable SST and relatively lower DO150m aid in the growth and predator avoidance of S. oualaniensis. Overall, the eddies in the Arabian Sea regulate the abundance and distribution of S. oualaniensis, with CEs providing a more suitable habitat.