How do you find a new species of dolphin in the 21st century?
The glamorous volunteer job at the marine mammal rescue society is carrying the beached dolphin away on a stretcher for fluids and rehab and an eventual fanfare-filled return to the ocean. Less glamorous is the job of picking up a several-day old dolphin carcass and transporting it for necropsy. Least glamorous of all is flensing, in which volunteers (aka undergraduate marine biology majors) use blunt chef’s knives to strip (or flense) the decaying flesh of dolphins’ faces from their skulls. The rescue society where I volunteered saved a year’s worth of dolphin heads in freezers so that they could be flensed all at once, at a sort of macabre outdoor festival. Despite repeated scrubbing of my skin, hair, and clothing, the rancid smell of dolphin flesh clung to me for days. Years later, I can still vividly recall that smell.
I am happy, then, when I hear of a study in which dolphin skulls are put to good use, such as the recent Molecular Ecology paper that identifies differences between groups of humpback dolphins and proposes the recognition of a new species (DOI: 10.1111/mec.12535). Researchers from the American Museum of Natural History and other organizations examined the morphology of 180 humpback dolphin skulls and analyzed the DNA of 235 tissue samples to reach their conclusions.
Only four new species of dolphins have been named since the 1800s. Thirty-six species of oceanic dolphins are officially recognized by the arbiters of such things, the International Whaling Commission and the Society of Marine Mammalogy. They currently recognize two species of humpback dolphins. All are of the genus Sousa; the S. teuszzi is found in the Atlantic Ocean along the west coast of Africa, while the remaining species are found in the Indo-Pacific. The new paper proposes dividing the Indo-Pacific group into three: S. plumbea, found in coastal waters from East Africa to India; S. chinensis, found near Southeast Asia; and an unnamed species found near northern Australia.
Humpback dolphins are named for the prominent hump at the front of their dorsal fins. They have long, well-defined beaks. Coloration ranges from dark gray with lighter gray bellies, to completely white verging on pink. They are typically smaller than the bottlenose dolphins common in aquariums, ranging in length from 5’10” – 8’6” and weighing between 220 – 300 pounds.
It’s not as if no one was aware that there were dolphins off the coast of northern Australia, so why is renaming them such a big deal? Conservation status and management polices are determined at a species level, so better decisions can be made when species are appropriately separated and counted. Currently the Atlantic species is listed as “vulnerable” and the Indo-Pacific group listed as “near threatened”. All of the known humpback dolphins live in coastal waters, many near the shores of developing nations with limited budgets for research and environmental protection. Many humpback dolphins are exposed to coastal water pollution and incidental mortality from fishing gear. Hopefully this new study will provide the information to better inform conservation programs, and spur interest in the research and protection of humpback dolphins.
Humpback dolphin image is by flickr user Megan Choo and is used under a Creative Commons Attribution 2.0 license.
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