An international team of biologists has made the first-ever field observations of one of the least known species of whales in the world--Omura's whales--off the coast of Madagascar.
In a paper published October 14, 2015, in the Royal Society Open Science journal, the researchers describe the whales' foraging and vocal behaviors, and habitat preferences in the shallow waters of coastal Madagascar.
For many years, these marine mammals were misidentified as Bryde's whales (picture on the left) due to their similar appearance--both are small tropical baleen whales with comparable dorsal fins, though Omura's are slightly smaller in size and have unique markings with a lower jaw that is white on the right side and dark on the left.
In 2003, using genetic data from samples obtained from old whaling expeditions and a few strandings in the western tropical Pacific, scientists determined Omura's whales were actually a distinct species (picture on the left). But there had been no confirmed records of sightings in the wild and little else has been known about the elusive species until now.
"Over the years, there have been a small handful of possible sightings of Omura's whales, but nothing that was confirmed," says lead author Salvatore Cerchio, who led the research while at the Wildlife Conservation Society. He is now at the New England Aquarium (NEAQ) and a guest investigator at the Woods Hole Oceanographic Institution (WHOI). "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."
So little is known about Omura's whales that scientists are unsure how many exist or how rare the species is.
The research team also observed four mothers with young calves. Using hydrophones, they recorded song-like vocalizations that may indicate reproductive behavior.