Tracking manta rays We conducted 8 years (2013–2021) of monitoring to provide the most comprehensive description to date of a reef manta ray (Mobula alfredi) nursery Investigating Reef manta ray nursery in Wayag lagoon, Raja Ampat Edy Setyawan – Institute of Marine Science Cannot swim backwards Give birth to only 1 pup every 2-6 years Largest brain- to-body ratio of all fishes Live at least 50 years Size at birth: 1.5–1.9 m from wingtip to wingtip Have NO sting! Feed on zooplankton Males are smaller than females Keep swimming to breathe QUICK FACTS! Satellite telemetry (2015 & 2017) Aerial survey (including drone photogrammetry) Boat surveys Underwater surveys Passive acoustic telemetry (May 2019–Sept 2021) VR2W acoustic receiver stations (n = 5) Acoustic transmitters (n = 9) Satellite transmitters equipped with GPS (n = 5) Shelter from predators Social interaction & learning opportunity Sufficient food source Benefits of living in a nursery Cleaning stations like ‘spa’ A nursery is a good and safe environment contributing to higher chances of newborn survival! Palmyra Atoll Flower Garden Banks Florida Raja Ampat Nusa Penida The Maldives How to define a nursery for manta rays? See Criteria! Potential manta ray nurseries 1) are more commonly encountered in this area than in other areas 2) tend to remain and/or return to this area repeatedly for extended period** 3) inhabit the area across years As applied on manta rays, pups and juveniles: Criteria of an elasmobranch* nursery The ecology of newborn and juvenile manta rays is understudied Identifying critical habitats (i.e., nurseries) is urgently required to support conservation effort Most species of sharks and rays use shallow sheltered habitats like lagoons as nurseries for their newborns Residency and continuous occupancy of juveniles in the Wayag lagoon Home range and spatial movement pattern in and around the Wayag lagoon Application of drone to locate & measure manta rays, and collect their photo IDs Each manta ray has unique spot pattern on its underside, like our fingerprints Manta ray pups live independently without parental care immediately after birth Key references: Heupel et al 2007 Mar. Ecol. Prog. Ser. Heupel et al 2019 Mar. Freshw. Res. Setyawan et al 2020 J. Ocean. Sci. Found. Setyawan et al 2022 Drones Stevens 2016 PhD Dissertation, Uni. of York Contact: Edy Setyawan edy.setyawan@auckland.ac.nz CONCLUSIONS • We conclusively confirm that the Wayag lagoon in Raja Ampat serves as a nursery for newborn and juvenile reef manta rays • Our study presents the most robust assessment and comprehensive description to date of a manta nursery Satellite telemetry • Restricted movements within Wayag lagoon • Narrow core activity space within and around Wayag lagoon • Occasional brief excursions to areas outside of the lagoon up to ~45 km Application of photo ID to identify juvenile manta rays * cartilaginous fish (sharks, rays, and skates) ** best to be assessed using satellite and/or passive acoustic telemetry MAIN findings Manta sightings The estimated body size (disc width) of juveniles ranged from 150 to 240 cm (n = 34). Two juveniles sized 218 and 219 cm were measured using drone. unique IDs 34 47 Newborn and juveniles reef manta rays in Wayag lagoon in 2013–2021 encounters 27 resighting rate (%) 21 longest sighting span Lagoon Backyard Far Inner Lagoon Inner Lagoon Main Lagoon Entrance Front Entrance VR2W acoustic receiver stations Manta nurseries are RARE! It requires massive & long-term effort to identify a nursery area Wayag lagoon is protected within West Waigeo Marine Park A touristic destination with picturesque limestone karst islands Wayag is located the northwest of Raja Ampat archipelago zooplankton Global population decline due to fishing pressure Supported by: Long-term and high residency of juvenile manta rays within Wayag lagoon! months of near-continuous detections 14.5 119 days of consecutive detections 0 detection by receivers outside of Wayag in broa