They stay there for a few years – which could increase their chance of survival – before they are large enough to join adult populations, like those in the study areas. Following this period, many of the expected baby manta rays likely live in sheltered nursery areas like Wayag lagoon or Fam Islands, both situated in Raja Ampat. These then increased opportunities for manta rays to feed in large feeding groups, enabling the manta rays to store much energy for reproduction and for mating.ĭuring and shortly after the El Niño events, we observed high number of pregnant rays in the populations. We also found that El Niño events generated more intense upwellings (upward motion of seawater) – bringing cold and nutrient-rich water to the surface. These sites, where manta rays frequently visit and gather for feeding and to be cleaned of parasites by cleaner fish, are important for their survival and health. Almost all known feeding and cleaning sites are located within the 2 million hectare marine protected area network. The thriving populations of reef manta rays strongly suggest this species is well protected in Raja Ampat waters. These resulted in the increase in manta ray populations in both marine protected areas. Furthermore, the populations typically saw a 20% boost from new individuals annually, which can be from newborns and/or larger rays from outside study areas. Each year, up to 93% of individuals in the populations survived. The manta rays were estimated to have high survival rates. South East Misool’s population increased at a higher rate of 10.7% per year, from 210 to 511 individuals over a decade of study. In Dampier Strait, the estimated population increased from 226 to 317, with an annual compound growth rate of 3.9%. We used the sighting data to look into reef manta ray demographic trends in two marine protected areas with the most consistent data collection over a decade: Dampier Strait and South East Misool. PLEASE go through your files and send any manta images taken in Raja Ampat either directly to Edy Setyawan ( or upload them on the Bird’s Head Seascape Manta ID database. Our research team managed to collect and curate manta ray images and sighting data from 2009 to 2019, thanks to citizen scientists and collaborators – especially divers and dive operators who contributed their manta ray photos. It also provides a reason for optimism when an integrated approach is adopted for shark and ray conservation initiatives. Our research is the first in the world to report thriving populations of this megafauna. This study suggests that the long-term implementation of conservation and management efforts implemented by Raja Ampat government has been fruitful. Our new research, published in Frontiers in Marine Science, found reef manta ray populations in Raja Ampat have thrived over a decade of our study. After 15 years of this initiative, its impact on manta ray populations had not been assessed. Since then, manta rays in the region have begun to enjoy some protection. ![]() To protect marine biodiversity and ensure food security for local communities, the Raja Ampat government officially developed a marine protected area network in 2007. In the 1990s and early 2000s, sharks were heavily caught in Raja Ampat using large gillnets and longlines, not to mention other illegal and destructive fishing practices by outsiders. In Raja Ampat, there were anecdotal reports from the local community suggesting that reef manta rays were often caught unintentionally by non-local shark fishers. Some of these include East Nusa Tenggara and North Sulawesi (Indonesia), the Philippines, Papua New Guinea and Mozambique in Africa. Their populations have been depleted due to overfishing in many regions in Indo-Pacific. A female gives birth to only one pup every 2 to 6 years after about one year of pregnancy. Males start to sexually mature at 9 to 13 years old, while females require 13 to 17 years to mature. This species is characterized by late maturation and extremely low fertility, which make their populations especially vulnerable. They are not mammals, but cartilaginous fish that are related to sharks. Raja Ampat archipelago in West Papua is home to Indonesia’s largest population of reef manta rays, Mobula alfredi. Procedures for Private Vessels and Liveaboards. ![]() ![]()
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