Arabian Sea Humpback Whale Isolated for 70,000 Years
The small, endangered, non-migratory population has been home cooking for tens of thousands of years.
The Arabian Sea humpback whale may be the most isolated humpback population on the planet, keeping its home in the same place for tens of thousands of years. That's the conclusion reached in a new study of the marine mammal conducted by a research team from the Wildlife Conservation Society and the American Museum of Natural History.
The whale, currently classified as "Endangered" on the International Union for Conservation of Nature's (IUCN) Red List of threatened species, has proved difficult to study due to a limited amount of data from which to work. But the authors of a study just published in the journal PLOS ONE were able to analyze tissue samples from 67 Arabian Sea humpback whales, focusing on both mitochondrial and nuclear DNA.
The team then compared its genetic analyses with existing data from humpback whale populations in both the Southern Hemisphere and the North Pacific. They found that the Arabian Sea humpback is highly distinct from the Southern Hemisphere and North Pacific populations.
Meanwhile, the team's analysis of the gene flow of the creature suggested the Arabian Sea humpback originated in the Southern Indian Ocean. But it came to be isolated in the Arabian Sea, and has been there for 70,000 years. A fact that's "remarkable for a species that is typically highly migratory," the researchers wrote.
As a key follow-on to their findings, the researchers consider the Arabian Sea humpback's low prospects for abundant reproduction, as well as threats posed to it by mankind, and recommend that the whale be designated "Critically Endangered" on the IUCN's Red List.
Thanks to an effort by the Vancouver Aquarium and the National Oceanic and Atmospheric Administration's Fisheries department, scientists have used an unmanned aerial vehicle -- or a drone -- to monitor the health, movement and reproduction of killer whales. The team tracked northern resident killer whales off British Columbia, a group currently designated as threatened by the Species at Risk Act in Canada. Its custom-made hexacopter flew more than 100 feet above the whales -- far enough out of mind that the whales would not notice but still close enough to get tons of great detail. Killer whales travel in a family group for the better part of their lives. This family group includes a two-year-old calf (second from top), and a young-of-the-year (middle).
At issue for the team was a central question: Are the whales able to find enough food? These whales, like their British Columbia southern resident counterparts near Seattle, eat Chinook salmon, which are far smaller than they used to be. (Some of the salmon runs are also endangered, the NOAA says.) Here, two northern resident killer whales are photographed by the hexacopter. The whale on the left is in very poor condition and is thought by the researchers to have recently perished. The whale on the right, luckily, is considered healthy and in peak condition.
The drone photos can show scientists how fat or thin individual whales are, as well as which ones are pregnant and which calves are brought to term. In this photo, the female at top appears skinny and in poor condition. The female in the middle seems to be healthy and well fed. The whale at bottom is pregnant, the bulge in her body evident behind the rib cage.
A yearly census of mortality is not the most helpful of measures for how well a whale population is doing, the team says. That's because any problems the whales experience have already occurred and taken the whales' lives. The hexacopter "can give us a more sensitive measure that we might be able to respond to before whales die," said NOAA biologist John Durban in a release.
While the team's research permit allowed it to use a 100-foot limit above the whales for its studies, non-research permits restrict hexacopter approaches to, at closest, 1,000 feet above the creatures.
Here, a moment of playful behavior is caught between two killer whales, as they nuzzle each other, head-to-head.