Walking in the shallow waters of St Joseph Atoll, it soon becomes clear the area has an abundant ray population. Tiny mangrove whiptail rays, Himantura granulata, dart to and fro. Additionally, large adults frequent both the shallows and deeper waters of the lagoon. So while we’ve inferred that the atoll environment is likely a notable nursery area for this species, we recently watched behaviour that suggests the Atoll may also be a critical area for other phases of this species life cycle. The occurrence of mating stingrays raise a number of questions.
Could St Joseph Atoll be an significant breeding area for mangrove whiptail rays? Recently, while in the field for targeted research on juvenile sharks, we were witness to an aggregation of large mangrove whiptail rays in shallow water. Upon close inspection, the largest of the rays lacked the obvious claspers apparent on what appeared to be her six male suitors. Indeed, the group of rays moved quite close to two of us in the water, throughout we kept a sharp lookout for large lemon sharks lurking in the murky water. The only explanation we could come up with for the behaviour was that these were mating stingrays. The rays, unbothered by our close proximity, stuck around long enough for one of us to run back to camp to grab the drone.
By the time we launched the drone, there were only two males left following the female. Moments before the video starts, it appeared as though one of them coupled with the female. The rays subsequently each travel their separate ways, but not after giving all of us a show to remember.