Basking sharks are usually solitary species, but scientists have discovered recent aerial images that show swarms of over a thousand sharks gathering along the northeastern U.S., according to National Geographic.
Basking sharps are the world's second largest fish (32 feet long and weighing nearly 5,000 pounds), outsized only by the whale shark. Despite their heft, they are slow-moving filter feeders, not dangerous towards humans. Scientists spotted big groups of basking sharks while tracking endangered whales. Without the chance sighting, scientists may not have been able to discover this mysterious habit of these lumbering deep-sea creatures.
Researchers documented ten sightings of large groups of gathering sharks between 1980 and 2013 along the coast from Nova Scotia to Long Island in a paper published in Journal of Fish Biology. Previously, there had been about 10,000 documented sightings of basking sharks, 99 percent of them in groups of seven or less.
Aerial sightings can only offer scientists so much information. Other shark species gather for feeding, mating or protection from predators. Researchers speculate that the basking sharks could be gathering to feed on zooplankton, reducing the drag caused by their open mouths and conserving energy.
In the meantime, scientists are enlisting citizen scientists for help in a program called Spot a Basking Shark, asking anyone to report back whenever they spot the giant fish. Basking sharks only spend about 10 percent of their time at the surface, making sightings rare and valuable.
Observing the sharks behavior could help preserve the species - certain populations of basking sharks have been dropping along the West Coast, as humans hunt for shark liver oil and hides. Then again, maybe sightings are low not because their populations are dwindling, but because we haven't seen them.
Source: National Geographic
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