Influence of Satellite Derived Oceanographic Parameters on Indian Mackerel Rastrelliger kanagurta (Cuvier, 1817) Abundance at the Visakhapatnam Coast

Abstract

This study investigates the influence of oceanographic parameters on Indian mackerel (Rastrelliger kanagurta) landings at Visakhapatnam Fishing Harbour, Bay of Bengal, from January 2024 to April 2025. Monthly landings data, varies from 37.81 t to 551.60 t, were analyzed alongside satellite-derived environmental variables: Sea Surface Temperature (SST), Chlorophyll-a (Chl-a), Photosynthetically Active Radiation (PAR), and Diffuse Attenuation Coefficient at 490 nm (Kd490), obtained from NASA’s MODIS-Aqua at 4 km resolution. Spearman’s rank correlation analysis revealed a strong negative correlation between mackerel abundance and SST, indicating higher catches during winter months. Weak and non-significant correlations were found with Chl-a and PAR, suggesting limited direct influence on monthly landings. A strong positive correlation between Chl-a and Kd490 confirmed elevated turbidity during monsoon-driven phytoplankton blooms. Seasonal landings peaked in December–February, aligning with optimal SST, and plummeted in April, potentially due to spawning or regulatory restrictions. These findings highlight SST as a primary driver of mackerel distribution, advocating for adaptive management strategies like seasonal fishing regulations to ensure fishery sustainability amidst climate variability, monsoon dynamics, and anthropogenic pressures, supporting resilient coastal ecosystems and local fishing communities.