Scientists from the Wildlife Conservation Society (WCS), the American Museum of Natural History (AMNH), the Environment Society of Oman, and other organizations have made a new discovery in the northern Indian Ocean: humpback whales living in the Arabian Sea are the most genetically distinct humpback whales in the world and could be the most isolated whale population on the planet.
The results would mean the species has remained separate from other humpback whale populations for nearly 70,000 years.
The study appears in the most recent edition of the online journal PLOS ONE.
Humpback whales, which are mainly known for their songs and acrobatics, hold the record for the world's longest mammal migration. Humpbacks have been tracked over a distance of more than 9,000 kilometers between polar feeding spots and breeding locations, according to a WCS press release.
"The epic seasonal migrations of humpbacks elsewhere are well known, so this small, non-migratory population presents a wonderful and intriguing enigma," said WCS researcher and study co-author Tim Collins, according to the release. "They also beg many questions: how and why did the population originate, how does it persist, and how do their behaviors differ from other humpback whales?"
Researchers analyzed nuclear and mitochondrial DNA extracted from tissue samples collected from the biopsies of 47 different whales to assess the origins of the Arabian Sea humpback population. Next, they compared the samples with data sets from humpbacks in both the North Pacific and Southern Hemisphere.
"We have invested lots of energy working to clarify the population structure of several large whale species around the world," said Dr. Howard Rosenbaum, Director of WCS's Ocean Giants Program and senior author on the study, according to the study. "The levels of genetic differences for Arabian Sea humpback whales are particularly striking; they are the world's most distinct population of humpback whales and might even shed some light on the environmental factors that shape cetacean populations."
The scientists found that the population was genetically distinct and had been separated for nearly 70,000 years, according to the study. They believe the separation could be linked to a number of glacicla incidents during the Pleistocene Epoch and shifts in the strength of the Indian Monsoon.
"The Arabian Sea humpback whales are the world's most isolated population of this species and definitely the most endangered," said Rosenbaum,. "The known and growing risks to this unique population include ship strikes and fishing net entanglement, threats that could be devastating for this diminished population; we need to see increased regional efforts to provide better protection for these whales."
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