Nidhi G. D'Costa , Scarlett R. Taylor² , Alison Hochstetter³ , Shefali Bhatt² , Betty J.L. Laglbauer¹ , Daniel Fernando⁴ , Guy M. W. Stevens¹

1 The Manta Trust, Catemwood House, Norwood Lane, Corscombe, Dorset, DT2 0NT, United Kingdom
2 Global Reef, 45/1 M3 Koh Tao, Surat Thani, Thailand, 84360
3 Scuba Junkie, Block B, Lot 36, 91308 Semporna, Sabah, Malaysia
4 Blue Resources Trust, Colombo, Sri Lanka
Author    Correspondence author
International Journal of Marine Science, 2026, Vol. 16, No. 5   
Received: 01 Jan., 1970    Accepted: 01 Jan., 1970    Published: 04 Sep., 2026

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Manta and devil rays are globally threatened and highly vulnerable to overfishing. This study presents one of the first species-level analyses of mobulid landings, providing valuable baseline information for a fishery that remains poorly documented in Malaysian waters. The study analyzed catch composition, size structure, and demographic characteristics of mobulids landed in Semporna, Sabah (May 2011 to November 2014), combining fishery-dependent sampling and morphometric measurements. Over 75% of landings comprised Mobula mobular and M. thurstoni, with most individuals (n = 95) below size-at-maturity; specifically, 77.8% of M. mobular and 55.8% of M. thurstoni were immature. This composition raises concerns about growth overfishing, though spatial and temporal segregation may explain the demographic pattern.  Chronic year-round artisanal gillnet fishing, combined with weak legal protections and socio-economic pressures, including international gill plate trade, sustains high fishing mortality. These pressures threaten population viability, especially given mobulids’ slow growth and low fecundity. The study emphasizes the urgent need to expand legal protections to all mobulid species in Malaysia, improve species-specific monitoring and management, implement bycatch mitigation, strengthen trade enforcement, and engage fishery communities in alternatives. Coordinated regional conservation efforts under CITES and CMS, integrated with local actions, are critical to safeguard mobulid populations in Malaysian waters.

Mobulids; Juvenile bycatch; Regional fisheries; Legal protections