Scientists Track 'Mysterious' Basking Sharks

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Three Basking Sharks are seen feeding at the edge of Dun Aonghasa, a pre-historic stone fort dated from 1100 B.C. on the remote Aran Islands in Galway, Ireland May 13, 2016. REUTERS/Clodagh Kilcoyne

The basking shark (Cetorhinus maximus) is the world's second largest shark, capable of growing to more than 35 feet in length. But despite its size, sightings of the elusive creature are rare, and scientists know surprisingly little about them.

Now researchers are tracking the sharks using advanced new technology in an attempt to better understand the species and bolster conservation efforts, AFP reports.

For centuries, the animals have been the victims of overfishing driven by demand for their large fins—a highly-sought-after soup ingredient in China—as well as their meat and oily livers (which are sold as an aphrodisiac, health food and ingredient for cosmetics in Japan).

As a result, basking shark populations suffered huge declines over the course of the 20th century. Today, most fishing has ceased—except in China and Japan—but the species has never properly recovered, in large part, due to its slow rate of reproduction.

"It's a shark that remains very mysterious," Alexandra Rohr from APECS—a non-governmental research organization based in France dedicated to the study of shark, skates and rays—told AFP.

Rohr explained that a number of important facts are still unclear, including the size of the global population, the age that the sharks reach sexual maturity and the areas they go to reproduce.

Observations of the shark are far more common over the summer months in its normal geographic range—which includes coastal areas ranging from Newfoundland, Iceland and Japan to Florida, Argentina and Australia. The lack of winter sightings has led to suggestions that the sharks migrate to warmer waters or greater depths.

APECS have fitted new tracking technology on four basking sharks this year, adding to the three that they had already tagged in 2016. The data collected, combined with crowd-sourced information from divers, sailors and others, has indicated that the sharks have a far greater range than was previously thought

One female, for example, was located off the northern Scottish coast on September 20, 2016, before appearing south of the Spanish Canary Islands more than 2,000 miles away four months later.

Basking sharks are slow-moving and can weigh over 5 tons, according to the Florida Museum. Unlike the vast majority of sharks, they are filter feeders, not predators, and are often spotted swimming close to the surface, with their huge mouths wide open. They are capable of filtering a staggering 2,000 tons of seawater per hour to scoop up plankton.

The basking shark is currently categorized as "vulnerable" throughout its range and "endangered" in the northeast Atlantic and north Pacific by the International Union for Conservation of Nature (IUCN).

Despite the fact that the gentle giants pose little danger to passive humans, many tales of sea monsters throughout the centuries have been atrributed to sightings of multiple basking sharks swimming in single file.