New research has detailed the movement patterns and spatial networks of reef manta rays within the Raja Ampat archipelago in Southwest Papua, Indonesia, providing crucial information to protect this globally vulnerable species.
The report, entitled ‘Spatial connectivity of reef manta rays across the Raja Ampat archipelago has been published in the Royal Society Open Science, and has found that reef manta rays frequently move between nearby important habitats, such as cleaning stations and feeding sites, and only occasionally embark on long-distance travels within the archipelago.
Three sub-populations were identified, suggesting a metapopulation, or ‘population of populations’ with limited exchanges within Raja Ampat: within the Ayau atoll system in northern Raja Ampat; the reefs of northwestern Raja Ampat; and the reef system off southeastern Misool Island in southern Raja Ampat.
The research also pinpointed key areas that the mantas frequent within the spatial movement networks that are vital for the manta rays’ navigation and survival.
The five-year study (2016-2021), led by Dr. Edy Setyawan, together with the Raja Ampat Marine Protected Area (MPA) Management Authority, Konservasi Indonesia, Conservation International, Macquarie University, and the University of Auckland, tracked over 70 adult manta rays and used an advanced network analysis based on data from over 30 acoustic receivers.
Dr. Setyawan was surprised by the results, considering that reef manta rays can travel hundreds of kilometres without any obvious barriers to movement between these three regions in Raja Ampat, and noted, “The findings show that reef manta rays in each region tend to ‘stay close to home’ and rarely move between regions.”
“Our research sheds light on the complex movement networks of reef manta rays in Raja Ampat, emphasizing the need for a nuanced approach to their conservation,” added Dr. Setyawan. “Understanding these networks allows us to identify crucial habitats and movement corridors for reef manta rays, informing targeted conservation efforts that are vital for the species’ long-term survival,” he further emphasized.
Iqbal Herwata, the Focal Species Conservation Senior Manager for Konservasi Indonesia and a co-author on the paper, stated that the research findings could bolster the management of manta rays in Raja Ampat MPAs. “Based upon these important findings, we recommend that the Raja Ampat MPA Management Authority consider refining its approach to the management of the metapopulation of reef manta rays in Raja Ampat by creating three management units that each focus on a subpopulation of reef manta rays,” he suggested.
In the same vein, Dr. Mark Erdmann, Vice President of Asia-Pacific Marine Programs at Conservation International, and one of Dr. Setyawan’s PhD advisors, assesses that these findings urgently call for an expansion in the protection efforts for reef manta rays. “Our study also illuminates the significance of one manta ray aggregation site, known as Eagle Rock, located just south of Kawe Island, as a crucial hub in the movement network of Raja Ampat’s reef manta rays,” said Dr. Erdmann. “This finding underscores the urgent need to extend spatial protection to this area through an expansion of Raja Ampat’s MPA network, particularly given the developing threat to the area from exploratory nickel mining on nearby Kawe Island,” he added.
Syafri S.Pi, the head of the Raja Ampat MPA Management Authority, expressed his appreciation and acknowledged the significance of management recommendations from this study. “These research findings are crucial for refining conservation efforts for our iconic species,” said Syafri. “We will carefully and seriously consider these recommendations and work closely with the Raja Ampat Manta Working Group to refine and incorporate them into our current manta ray management strategy,” he affirmed.
Moving forward, the study also paves the way for future research, including detailed genetic studies and satellite telemetry work. These future investigations aim at further dissecting the population structure and home range of reef manta rays, and eventually enhancing the management and conservation strategies for Raja Ampat’s reef manta rays.
Animal,animal news,nature,nature conservation,wildlife
