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A new study led by the Manta Trust and a network of international experts has found that manta ray and devil ray populations are in global decline, with an estimated 265,000 individuals killed every year.
Published in the online journal Biological Conservation, the study provides a comprehensive global review of mobulid fisheries, and found that small-scale fisheries (those using vessels smaller than 15m in length) are responsible for 87 per cent of mobulid deaths.
The study found that non-selective gillnets are responsible for the bulk of the take, with the highest-risk spots in India, Indonesia, Sri Lanka, Peru, and Myanmar.
Mantas and mobulas are highly prized by the Asian markets for their gill-rakers, or gill plates – the tissue in their mouths which extracts both oxygen and prey from the water – which is dried and used in ‘traditional’ medicine.
Despite the fact that mantas and mobulas have been protected for almost ten years by the Convention on International Trade of Endangered Species (CITES) and the Convention on the Conservation of Migratory Species (CMS) – as well as national measures implemented by more than 40 countries – the study shows that exploitation and a lack of enforcement remain substantial global problems.
Three species of devil ray – bentfin, sicklefin and spinetail – were recently upgraded to Critically Endangered by the IUCN Red List of Threatened Species, while others, including two of the three species of manta ray, are listed as Endangered
‘This comprehensive picture of mobulid mortality shows how severe fisheries threats are and provides the context needed to prioritise conservation action,’ said Betty Laglbauer, lead author of the study.
‘We now have a data-driven understanding of global catch and of population declines – which underscores the urgency of stronger protections and effective management.’
The uplisting of all mobulid species to CITES Appendix I – the highest level of international protection – will be debated at this year’s Conference of the Parties to CITES (CoP20) on 24 November.
If the vote is successful, all international commercial trade in mobulid products would be prohibited – a vital step toward halting unsustainable exploitation.
Key findings from the study
- 264,520 mobulids are caught annually (95% CI: 184,407–344,987)
- Small-scale fisheries account for 87% of total mortality.
- Just five countries — India, Indonesia, Sri Lanka, Myanmar, and Peru — account for 85% of global catch and 87% of total mortality.
- The Indian Ocean is the epicentre of mortality, responsible for 74% of global deaths.
- Drift gillnets are the leading cause of mobulid captures in small-scale fisheries; purse seines dominate in larger fleets.
- Population declines of up to 99% have been documented in some regions.
‘Mobulids are among the most charismatic and biologically vulnerable marine animals,’ said Dr Guy Stevens, Chief Executive and Co-Founder of the Manta Trust.
‘This study provides the strongest evidence yet that overfishing, particularly by small-scale coastal fleets, is pushing these species toward collapse. The solutions are clear. What’s needed now is the political will to implement them.’
The study’s authors call for coordinated, science-based action to close existing management and policy gaps, recommending that all mobulid species be uplisted to CITES Appendix I.
The authors also urge the governments of the high-risk fishing nations to implement full national legal protection for mobulids and restrict fishing in known aggregation and nursery areas.
Restrictions should also be placed on the use of gillnets and other forms of high-risk fishing gear that result in mobulid rays being caught as bycatch.
The authors also call for more engagement of fishers and coastal communities to aid mobulid conservation through education, participatory management, and the development of alternative livelihood initiatives, such as encouraging fishers to provide tourist excursions rather than engage in unsustainable fishing practices.
‘Many of these animals are dying as retained bycatch from non-selective fisheries,’ said Nidhi D’Costa, Manta Trust researcher and one of the study’s co-authors.
‘Reducing mortality means both protecting species domestically and curbing the demand that fuels international trade.’
With mobulid populations in such sharp decline, the Manta Trust says it is urging governments to take decisive action to prevent further losses, but also calls on the public to support its efforts by backing the #SaveTheMantas campaign and signing the Only One petition to stop the international trade of whale sharks, oceanic whitetip sharks, and manta and devil rays.
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