High take of mobulid rays in East Java, Indonesia: landing trends and socio-economic context

October 2025

Betty J. L. Laglbauer, Muhammad G. Salim, Fahmi, Selvia Oktaviyani, Irianies C. Gozali, Firmansyah Tawang, Hasan S. Rizal, Vidlia P. Rosady, Didik Rudianto, Isabel Ender, Jorge M. R. Fontes, Pedro Afonso, Michael B. Bennett & Guy M. W. Stevens

Keywords: Manta ray • Mobulid Rays • Bycatch • Drift Gillnet • Indonesia • Fisheries • Conservation • Socio-economics • East Java

Summary: In Muncar, East Java, Indonesia, five mobulid ray species are caught primarily as bycatch in drift gillnets, with juveniles dominating landings. Pelagic longlines and purse seines also contribute to captures. Spinetail devil ray (Mobula mobular) catch rates have declined sharply over 2015–2024, and fishers perceive a general decrease in mobulid availability. Rays are used locally for smoked meat and, occasionally, gill plates enter international trade. The Bali Strait appears to serve as a key juvenile habitat. The study highlights urgent conservation needs, advocating expanded legal protection, bycatch mitigation, and socio-economic strategies for sustainable fisheries management.

Abstract

“Mobulid rays (genus Mobula) comprise ten species of highly threatened filter-feeding rays, seven of which occur in Indonesia and five of which are caught in small-scale fisheries off Muncar, East Java. We conducted a study in Muncar from 2015 to 2024 to assess mobulid ray catch composition, trends in mobulid ray catch rate, demography, and the socio-economic context of their fisheries through fish market surveys (n = 1467) and interviews with fishers (n = 30), fish collectors (n = 4), and processors (n = 15). The study shows that mobulid rays are at high risk from target and bycatch in Muncar and are mainly caught in drift gillnets. A declining trend in the catch rate of M. mobular, compounded by mobulid ray declines reported by fishers, and a majority of immature specimens across Muncar’s fisheries indicate that mobulid rays are likely overfished in East Java. Illegal landings of M. birostris and M. alfredi, and evidence of mobulid gill plate trade intended for international exportation highlight an urgent need for better enforcement of existing national protections and international conservation provisions. This study highlights a critical need for improved conservation of all mobulid ray species in Indonesia given their high extinction risk and the unsustainable fishing pressure they face. This will require swift enforcement of CITES through better trade control, improved protective legislation, and fisheries management for all mobulid ray species, with measures targeted toward local fisheries characteristics and socio-economic context.”

Full publication

Author Affiliations

  • The Manta Trust

  • Mobula Project Indonesia (Yayasan Konservasi dan Penelitian Pari Mobula)

  • Okeanos, Institute of Marine Sciences, University of the Azores

  • School of Biomedical Sciences, The University of Queensland

  • Research Center for Oceanography, National Research and Innovation Agency (BRIN)

  • Ministry of Marine Affairs and Fisheries

Funding (found in the acknowledgements of the paper)