About Shark Hibernation
The most feared sea-dwelling fish is the shark. The shark is a meat eater and normally found in warmer waters. At one time scientists speculated that basking sharks hibernated along the ocean's floor, but studies conducted in 2001 disproved that theory.
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Types
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There are about 350 species of sharks. One of the largest is the basking shark. They live in tropical and temperate waters and normally stay close to the surface, giving the appearance of basking, hence the name. They feed on small animals and plankton.
Size
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The only other shark larger than the basking shark is the whale shark. The basking shark can reach 32 feet in length.
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Geography
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The basking shark can be found in coastal and offshore areas which include Newfoundland, Canada, Florida, New England, and the Gulf of Maine. They are usually in mid-Atlantic in the spring and summer in Canada. Basking sharks occasionally make their way into inshore bays.
Identification
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Basking sharks are considered an endangered species. They have been targeted by the Asian market primarily for their single fin. The basking shark has a bulbous snout and large mouth, with a head that is encircled with large gill slits. Their skin is uneven and patchy in color, with hues that vary from a grayish-brown to dark gray color.
Features
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Basking sharks are known for the way they lazily swim along the ocean surface. Rather than basking, they are actually filtering plankton from the surface. Every winter the sharks disappear, and scientists once believed they were hibernating. This belief continued for about 50 years.
Theories/Speculation
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There were two other factors, aside from the sharks disappearing during the winter, which led scientists to believe the basking sharks hibernated during this time. Basking sharks have enormous livers, and fishermen noted that basking sharks caught in the spring had much smaller livers than those caught in the fall, leading some to believe they were reserving energy in their liver for hibernation. Scientists also believed that the basking sharks shed their gill rakers during the fall, which would make it impossible for them to eat during the winter, while the gill rakers were regrowing.
In 2001 David Sims, from the Marine Biological Association in England, placed satellite transmitters on 20 basking sharks to study the hibernation theory. The data proved the sharks were as active in the winter as they were during other months. What they did discover was that the shark preferred to winter in deeper water.
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