Population estimates of photo identified individuals using a modified POPAN model reveal that Raja Ampat’s reef manta rays are thriving.
The 6.7-million-hectare Raja Ampat archipelago is home to Indonesia’s largest
reef manta ray (Mobula alfredi) population and a representative network of nine
marine protected areas (MPAs). However, the population dynamics of M. alfredi
in the region are still largely unknown. Using our photo-identification database,
we fitted modified POPAN mark-recapture models with transience and per
capita recruitment parameters to estimate key demographic characteristics of
M. alfredi from two of Raja Ampat’s largest MPAs: Dampier Strait and South East
(SE) Misool. A total of 1,041 unique individuals were photo-identified over an
11-year period (2009–2019) from Dampier Strait (n = 515) and SE Misool (n =
536). In our models, apparent survival probabilities and per capita recruitment
rates were strongly linked with El Niño–Southern Oscillation (ENSO) events.
Our models also estimated high apparent survival probabilities and significant
increases in (sub)population sizes in both MPAs over a decade.