Huge increase in whale strandings along India's southwest coast: CMFRI

Kochi, Aug 12 (IANS) Whale strandings along India’s southwest coast have surged tenfold in the past decade, according to a study by the ICAR–Central Marine Fisheries Research Institute (CMFRI), raising urgent calls for region-specific conservation strategies in the face of climate change.

The analysis, covering data from 2004 to 2023, found that annual whale strandings jumped from just 0.3 per cent between 2003 and 2013 to three per cent during 2014–2023.

The increase is attributed to a combination of changing ocean ecosystems, human activities, and improved reporting through social media and citizen networks. Kerala, Karnataka, and Goa emerged as key hotspots, collectively accounting for the majority of cases.

Factors such as high vessel traffic, intensive fishing, noise pollution, ship strikes, habitat degradation, and shallow coastal shelves were identified as major contributors.

Bryde’s whales were found to be the most commonly stranded species, with occasional blue whale cases also recorded. The study also revealed genetic diversity within Bryde’s whale populations, confirming two distinct forms in Indian waters.

The trend reached a peak in 2023, when nine strandings, the highest in recent years, were documented, mainly between August and November.

The study linked strandings to environmental indicators, finding a positive correlation between chlorophyll-a concentrations and whale strandings during the southwest monsoon.

This nutrient upwelling attracts whales closer to shore for feeding, increasing the risk of stranding.

Rising sea surface temperatures and converging currents were also found to play a role, sometimes pushing weakened or dead whales onto beaches.

The researchers stressed the need for predictive models using satellite data on chlorophyll levels, wind patterns, and sea surface temperatures to anticipate high-risk periods.

"Region-specific conservation strategies are required to address this marine biodiversity threat in one of the country’s richest oceanic zones," said Dr R. Ratheesh Kumar, lead author of the study published in Regional Studies in Marine Science.

Dr Ratheesh Kumar is also the principal investigator of the national project on Marine Mammal Stock Assessments in India.

Recommendations include real-time alert systems, strengthening marine megafauna conservation networks, training fishers and officials, and expanding citizen science platforms for better data collection.

The findings, the CMFRI warns, highlight the urgency of building robust marine mammal conservation infrastructure to safeguard the fragile ecosystems of India’s southwest coast.

--IANS

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