This video, recorded off Peru, says about itself:
Curious giant manta ray surprises manta researcher! The manta researcher was collecting a photo ID, used to monitor population trends that can help identify the effects of fishing pressure on this population of manta rays.
Full story here.
See also here.
Peru Affords Full Protection to World’s Largest Known Manta Population: here.
4 things we’ve discovered from tagging Indonesia’s mantas: here.