First-ever reef manta ray spotted in the eastern Pacific

March 20, 2019, 12:39 p.m.
A coastal manta ray swinging near Cocos Island
Photo: Mauricio Hoyos

Sometimes, you just need a change of scenery. A pregnant reef manta ray (Mobula alfredi) has been spotted swimming far offshore in the Eastern Pacific Ocean, near Cocos Island, which is a long way from the creature's traditional home.

Reef manta rays — as their name implies — generally stick to coastal regions, and they prefer the tropical and subtropical waters found in the Indian and Pacific oceans. The one above, however, is far from the species' normal swimming grounds. The marine creature was seen in September 2018 some 3,728 miles (6,000 kilometers) from the nearest confirmed sighting location of a ray in the Marquesas Islands and about 311 miles from "any other suitable habitat," according to a March 2019 paper published in Marine Diversity Reports that details the manta ray's spotting.

"Reef mantas may travel several hundred kilometers, although they tend not to travel too far offshore," said Randall Arauz, one of the authors of the report and a policy and development specialist for Fins Attached, a marine research and conservation organization. "It is unclear how this individual could have steered so far off course, leading us to assume it was not intentional."

The ray's pregnancy is also notable. Manta rays are slow to reproduce, birthing a single pup once every 2.5 years or so. No one has ever seen a manta ray give birth before. Arauz also pointed out that if it hasn't happened already, the pup may be born in the Cocos Islands.

A pregnant reef manta ray swimming through the waters near Cocos Island This reef manta ray is thousands of miles away from where its species is traditionally found. (Photo: Mauricio Hoyos)

If the ray did indeed swim into these waters on purpose, it may change what we know about the animals. Researchers fitted the ray with an acoustic tag that will ping the listening trackers located around Cocos Island. Such trackers are also placed near other islands in the Eastern Pacific, including the Galapagos. So if the manta ray swims there, researchers will know about it.

"It will be interesting to monitor her over the coming months and see how she uses this new, unfamiliar habitat," Andrea Marshall, co-founder and principal scientist at the Marine Megafauna Foundation said. "If she adjusts well to the conditions, it begs the question: why do reef mantas not ordinarily live in this part of the ocean? While unlikely, we also cannot ignore the possibility that small populations of reef mantas may in fact exist in the eastern Pacific and have just gone undetected.

"Perhaps most importantly, this research also provides tantalizing clues to how reef mantas may have so prolifically colonized the remote islands and archipelagos of the Indian Ocean and South Pacific."