Photos of Madagascar Omura's whales (Balaenoptera omurai) reveal their unique pigmentation and anatomy. Photo by Salvatore Cerchio/Woods Hole
WOODS HOLE, Mass., Oct. 22 (UPI) -- The first field observations of Omura's whales were published this week in the journal Royal Society Open Science.
Omura's whales are one of the least understood species in the world. For decades the species was misidentified as dwarf version of Bryde's whales. But 2003 DNA testing from whale hunting records and a few stranded whales confirmed the species' genetic uniqueness. Scientists had not, until now, studied the species live in the wild.
"Over the years, there have been a small handful of possible sightings of Omura's whales, but nothing that was confirmed," lead study author Salvatore Cerchio, a whale researcher with the Wildlife Conservation Society, said in a press release. "They appear to occur in remote regions and are difficult to find at sea because they are small -- they range in length from approximately 33 to 38 feet -- and do not put up a prominent blow."
In 2011, Cerchio, now serving as a guest investigator at the Woods Hole Oceanographic Institution, was leading a team of international researchers on an expedition off the coast of Madagascar, when they spotted what they at first thought was a Bryde's whale.
On a similar expedition in 2013, Cerchio and his colleagues realized they were witnessing the surfacing of Omura's whales. The species' unique asymmetrical pigmentation on their lower jaws gave them away.
"From the little information on their habitat and range, Omura's whales were not supposed to be in that part of the Indian Ocean," Cerchio said of the serendipitous discovery.
For two years, Cerchio and his crew followed the whales, observing the movement and behavior of 44 groups. They were able to collect skin biopsies from 18 adult Omura's whales. Researchers also observed four mothers with newly born calves, and recorded vocalizations that could offer clues to the whales' reproductive behaviors.
"What little we knew about these whales previously came primarily from eight specimens of Omura's whales taken in Japanese scientific whaling off the Solomon and Keeling Islands and a couple strandings of dead animals in Japan," Cerchio explained. "This is the first definitive evidence and detailed descriptions of Omura's whales in the wild and part of what makes this work particularly exciting."
Cerchio and his colleagues are planning a new expedition to further study the species' vocalization. The team also hope to apply satellite tags, so scientists can track the whales into other regions.