Marine Heatwaves Are Pushing India's Coastal Fish Stocks Beyond Artisanal Fishers' Reach

Marine heatwaves in the Indian Ocean are forcing temperature-sensitive species such as sardines and mackerel into deeper and more northerly waters, placing them beyond the range of the non-motorised and small motorised craft on which most of India's artisanal fishers depend. Kerala's sardine catch has declined 57 per cent over the past decade as sea temperatures regularly exceed the species' thermal optimum.

CMFRI data shows that total marine fish production in 2025 reached 35.7 lakh tonnes — a 3 per cent increase over 2024, generating Rs 69,254 crore at landing centres, up 10 per cent year on year. However, the recovery was concentrated in species less sensitive to thermal stress. As of May 2026, the Indian National Centre for Ocean Information Services had issued marine heatwave alerts across six Indian Ocean basins, with nearly 36 per cent of the Arabian Sea under varying degrees of heat stress. A 2026 study found that the Indian Ocean could experience 220–250 marine heatwave days per year by 2050.

The human cost is measurable. CMFRI data from 2024 shows non-motorised boats landed just 41 kg per trip compared with 2,959 kg for mechanised craft. In early 2024, sardine scarcity along Kerala's southern coast drove prices to Rs 350–400 per kilogram — beyond the reach of low-income households that historically depended on sardines as their primary animal protein source. Around 70 per cent of post-harvest fisheries activity in India is undertaken by women, who absorb the first economic shock when catches become erratic.

India's Marine Fisheries (Regulation and Management) Act contains no provision for temperature-linked stock advisories, no mechanism for dynamic fishing zone adjustments tied to real-time sea surface temperature data, and no climate vulnerability classification for species in quota or licensing design. The author calls for embedding INCOIS marine heatwave data into dynamic fishing zone advisories, redesigning species-specific quotas for thermally driven stock displacement, and treating coral reef and seagrass restoration as fisheries infrastructure. The fisheries sector employs over 30 million people in India.

Key figure — 57% decline in Kerala's sardine catch over the past decade