Scientists unraveling mystery of rare whales off Madagascar

Omura's whale mother and calf. (B. Andrianantenaina)

More than a decade ago, Salvatore Cerchio went to Madagascar to study coastal dolphins. But his attention eventually shifted to a much bigger marine mammal – a rare species of whale that calls those waters home.

Cerchio, who works for the New England Aquarium, discovered the Omura’s whale in waters off the island nation in 2013 and his team had 80 sightings of the whale last year. Much of their work during that time has been trying to better understand the behavior of a whale that until 2003 was mistakenly thought to be a similar looking species, the Bryde's whale.

“When we found them, we thought they were Bryde's in part because they weren’t supposed to be in this area. The known range of Omura’s whales at that point was the western Pacific and the far eastern Indian Ocean off of Australia,” Cerchio told FoxNews.com.

“So after seeing these animals a few times in Madagascar, it occurred after we got some pretty good underwater video that these are not Bryde's whales at all but actually Omura’s whales,” he continued. “Once we realized they were Omura’s whales, it was mind boggling because first of all no one had studied these animals. No had seen them or documented them in the wild and they were not supposed to be in Madagascar. The work that we’ve done has extended their range significantly.”

In October, Cerchio released the first video of the whale in the wild and now has fresh data on the feeding and breeding behavior of these 33- to 38-foot mammals. They came to realize the whales were feeding on levels of “tiny shrimp” known as euphasiids were being found in the water.

“What was exciting is that we got more information on their feeding than we ever had before,” he said.

“They spend their entire lives in the tropics. That is really unusual and special because the tropics are a difficult to make a living,” he said of the clear blue waters that often compared to a desert when it comes to food offerings for whales. “How does a whale, even a small whale, make a living in a desert? That, in itself, is a fascinating question. The fact we are seeing them feed – and getting data on what they are feeding on – is a great opportunity to learn about an ecosystem and how the species fits into that ecosystem.”

Along with the feeding, Cerchio and his team documented five mother/calf pairs – evidence they believe that this is a resident population living off the southeast coast of Africa.

“We saw more mother and calves than we had before. In the previously year, we had no moms and calves. In 2015, we had five different moms and calves which is great,” he said. “That means this is a productive area. They are reproducing here, probably giving birth nearby because these were young calves.”

The team also collected two weeks of continuous acoustic data from remote recordings of the whale singing – and plan to retrieve recorders in April, which will have six months more data on them. The singing – which has been seen in Humpback and Fin whales – has been less studied in tropical species.

“They sing, which is by itself a very exciting discovery,” Cerchio said. “They sing a very simple but interesting song. It’s very rhythmic and they repeat the same vocalization for hours on end. You have groups of animals singing in a chorus … These guys are feeding, breeding and singing all in the same habitat.”

The discovery of the whales in Madagascar - and mor recently Mauritania - has added urgency to what Cerchio said is a need to protect a relatively small population. Among the threats they face are getting tangled in fishing lines as well as the noise from oil and gas operations.

“Whenever you have a small population like this, they tend to be more vulnerable to any local threats,” he said. “The small resident populations tend to have low genetic diversity and also be subject to any environmental pressures that are in that area such as oil and gas exploration.”

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