Scientists from the Woods Hole Oceanographic Institution have made the first-ever field observations of the world's rarest whale species – Omura's whale – off the coast of Madagascar, according to a news release. After spotting this elusive species in 2011, the international team of researchers were finally able to record the marine animal's foraging and vocal behaviors as well as its habitat preferences.
"Over the years, there have been a small handful of possible sightings of Omura's whales, but nothing that was confirmed," said Salvatore Cerchio, lead researcher who was working with the Wildlife Conservation Society at the time of the study.
Omura's whales have often been misidentified as Bryde's whales due to their similar appearance. Both species are small, tropical baleen whales with similar dorsal fins. However, Omura's are slightly smaller in size with a unique asymmetrical pigmentation on their head and jaw, where the right side is white and the left side is dark.
When researchers caught a glimpse of the Omura's whales in 2011, they too mistook them from Bryde's whales. They were only able to determine the animals were Omura's whales after moving study areas and encountering more of the animals with distinct markings swimming by.
"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 explained in the release.
Omura's whales were first identified as a distinct species in 2003, after genetic data was collected and analyzed from old Japanese whaling expeditions off the Solomon and Keeling Islands and a few dead individuals stranded in areas throughout Japan. However, this is the first sighting of the species in the wild and provides vital information about the secretive animals.
"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," Cerchio added.
Following their sighting in 2011, researchers observed a total of 44 groups over the course of the following two years. This gave them the opportunity to collect skin biopsies from 18 adult whales, which were then used to confirm the whales' species.
Using hydrophones, researchers were also able to pick up song-like vocalizations, which they suggest could represent a distinctive mating call or other reproductive behavior. However, Cerchio plans to return to the field to continue studying these vocalizations, the release noted.
In total, researchers have been able to catalogue roughly 25 individuals using photographic identifications. Their study was recently published in the Royal Society Open Science journal.
A video of an Omura's whale swimming off the coast of Madagascar can be seen online.
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