Population estimates of photo-identified individuals using a modified POPAN model reveal that Raja Ampat’s reef manta rays are thriving

Using 11 years of photo-identification data and a modified POPAN mark–recapture model that accounts for transience and per-capita recruitment, this study shows that reef manta ray (Mobula alfredi) populations in Raja Ampat’s Dampier Strait and South East Misool MPAs have increased significantly over the past decade, with compound annual growth rates of ~3.9% and ~10.7%, respectively. High apparent survival, strong recruitment, and elevated pregnancy rates—particularly during ENSO-driven productive periods—indicate that manta rays are responding positively to long-term protection. These results provide rare quantitative evidence that a well-enforced MPA network, combined with full legal protection, fisheries restrictions, and regulated tourism, can enable recovery and sustained growth of a highly vulnerable elasmobranch population, underscoring the importance of long-term monitoring to evaluate conservation effectiveness.

Authors:

Edy Setyawan, Ben C. Stevenson, Mark V. Erdmann, Abdi W. Hasan, Abraham B. Sianipar, Imanuel Mofu, Mochamad Iqbal Herwata Putra, Muhamad Izuan, Orgenes Ambafen, Rachel M. Fewster, Robin Aldridge-Sutton, Ronald Mambrasar, Rochelle Constantine

Publisher:

Frontiers in Marine Science

Keywords:

marine protected areas, marine megafauna, mark-recapture, citizen science, Indonesia, conservation, abundance estimation, population dynamics

Group Species:

Elasmobranch

Species:

Reef manta ray

Scale:

Raja Ampat

Year:

2022