An international team of marine biologists has made the first-ever field observations of rare Omura's whales — one of the least known species of whales in the world — while working off the coast of Madagascar.
Omura's whales are so rare that scientists are not sure exactly how many exist.
"Over the years, there have been a small handful of possible sightings of Omura's whales, but nothing that was confirmed," noted lead author Salvatore Cerchio in a Woods Hole Oceanographic Institution 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."
Cerchio, who works out of the New England Aquarium (NEAQ), says that all previous knowledge came from eight specimens of Omura's whales taken in Japanese scientific whaling off the Solomon and Keeling Islands, along with a couple of strandings in Japan.
After a possible sighting near Madagascar in 2011, the team decided to relocate their efforts to the region. It proved to be an excellent move, resulting in the two year study, the details of which now appear at Royal Society Open Science.
Five different individuals
"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," he says.
The researchers observed 44 groups and were able to collect skin biopsies from 18 adult whales. These samples were sent to Northern Michigan University for DNA analysis, the results of which confirmed the species as being distinct. Up until recently, some scientists thought that Omura's whales were actually Bryde's whale.
Cerchio's team documented various physical and behavioural characteristics of the whale.
They're mostly dark grey, but have a prominent white patch on their right lower jaw. They lunge feed, which means they subsist on a steady diet of zooplankton. The presence of so many mothers with young calves suggests that the study site was at or near a breeding habitat where females give birth. The team was also able to make recordings of Omura's whale song, which appears to be a male-limit trait (which isn't unusual among whales, including sperm whales).
Read the entire study at Royal Society Open Science: "Omura's whales (Balaenoptera omurai) off northwest Madagascar: ecology, behaviour and conservation needs".