Sightings trends and behaviour of manta rays in Fernando de Noronha Archipelago, Brazil

Abstract Despite substantial progress in mobulid research over the past decade, knowledge gaps in manta ray ecology and behaviour remain, particularly in the South Atlantic Ocean. Opportunistic photographic and video records of manta rays collected between 2002 and 2019 at Fernando de Noronha Archipelago (FNA) in northeast Brazil provide evidence to support the year-round use of the region by manta rays (believed to be Mobula cf. birostris). From a total of 130 sighting records, manta rays exhibited feeding behaviour in 36.9% (n = 48) of sightings, indicating that the shallow waters surrounding the archipelago are used as feeding grounds. Approximately half of the records (53.8%) corresponded to identified individuals that were re-sighted repeatedly, using the area in different seasons and for several years. Of the compiled records, 69.2% of sightings were of small individuals (≤3 m disc width). All identified males had undeveloped claspers and females had no visible mating scars, suggesting a juvenile population. Despite being limited to a small local sample, here we present the first report of manta rays at FNA and provide preliminary evidence of feeding behaviour by juvenile manta rays in Brazil. This information contributes to our understanding of the regional distribution and habitat use of manta rays in Brazilian waters.