Expedition to Palmyra Atoll: Manta Ray Alley

(Editor’s Note: Alison Green, senior marine biologist at The Nature Conservancy, is spending the next two weeks diving and exploring Palmyra Atoll as part of the first marine assessment of the atoll. Follow her posts from Palmyra on Cool Green Science…and learn more about the expedition.)

Have you ever seen a giant manta ray (Manta birostris)?

They’re huge, majestic creatures with wing spans of up to 22 feet (6.7 meters) across.  They glide effortlessly through the water column with their mouths open feeding on plankton.

Unfortunately, in many places in the world. manta rays are killed by local fishermen, either intentionally or accidentally. But here at Palmyra Atoll they’re protected, so there are a lot of them. And I mean A LOT of them.

Today we went on two drift dives through the channel from the outer reef into the lagoon — channels are always a great place to see sharks, rays and other big reef fishes.   There were so many manta rays that now I call it Manta Ray Alley.

On each dive we saw at least 10 mantas, which swam right up to us, and did pirouettes around and over us.  I could have reached out and touched them.

Lots of mantas swirling around you is a magnificent sight, but it makes them difficult to count.  Fortunately, each manta ray has distinctive markings, so it is possible to identify individuals. One of the Nature Conservancy staff in Palmyra, Kydd Pollock, has been building up a photo library of manta rays, so one day we hope to have a better idea of how many there are at Palmyra.

Because manta rays feed on plankton, and plankton is attracted to lights, the mantas also come into the boat harbor at night to feed under the lights. At Palmyra, we spend our evenings watching manta rays feed beside the jetty, which is much better than watching the telly!

(Video: Manta Ray at Palmyra Atoll. Credit: Eric Conklin.)

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