Small-Scale Fisheries Threaten Manta and Devil Rays Across Global Waters

Roughly 259,000 manta and devil rays, known collectively as mobulids, die each year in fisheries around the world. Five countries account for 87 percent of these deaths, with India leading as the highest contributor at 28.2 percent, followed by Indonesia, Sri Lanka, Myanmar, and Peru. Small-scale fishing operations drive most of these mortality numbers. Limited catch data and a poor understanding of how these fisheries impact marine life make it hard to assess the survival status of these species.

Local Findings

Researchers tracked mobulid bycatch from fishing boats in Thoothukudi, Tamil Nadu, across two periods from 2013 to 2023. Published in Conservation Science and Practice, the study recorded 8,163 mobulid landings of six species and some unidentified ones across two district landing sites, Threspuram and Tharuvaikulam. The spinetail devil ray proved most common, making up 86 percent of the bycatch. Landings per vessel fell sharply for several species at Threspuram over the decade, dropping 86 percent for spinetail devil rays, 92 percent for sicklefin devil rays, and 83 percent for manta rays. Despite these drops in per-vessel catch, total ray landings rose by 4 percent due to larger fleets and more advanced fishing tech that lets boats travel farther.

Population Changes

The study revealed declining numbers for four specific species: the spinetail devil ray, the sicklefin devil ray, the oceanic manta ray, and the bentfin devil ray. The average disc width of spinetail devil rays shrank by 10 centimetres over the decade, a change researchers link to fewer adults surviving in the population rather than adults shrinking. The proportion of adult spinetail devil rays dropped heavily from 64 percent down to 26 percent. Because these rays produce just one pup every two to three years, this drop in adults leaves fewer recovery paths for the species. Drift gill nets accounted for 98.9 percent of all mobulid landings in Thoothukudi, with tuna-targeting fisheries causing 50.2 percent of the total bycatch.

Policy And Protection

India's Wildlife Protection Act of 1972 gives different protection levels to these fish, with manta rays receiving top-level Schedule I status in April 2023 to ban hunting and trading. However, sicklefin devil rays fall under Schedule II, and the other four devil ray species sit under Schedule IV. Globally, all 10 manta and devil ray species entered CITES Appendix I in November 2025 to ban commercial international trade, though experts note this does not control domestic catches. Without compensation to release accidental catches, fishers sell the rays locally for consumption.

Context

Marine species like sharks and rays face heavy pressures when small-scale coastal fishing gear overlaps with their natural feeding grounds in shallow waters. International trade rules often fail to stop local catches and domestic markets from driving vulnerable marine species toward population collapse. Better monitoring of fishing gear types and vessel habits helps scientists track actual population health instead of relying on raw catch totals.