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Whale Sharks Shrinking! June 9, 2006

Posted by Administrator in Sharks.
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Whale Shark That's right, the Whale Shark (Rhincodon typus) is shrinking. In the last decade alone, the average length of the Whale Shark has gone down from 23 feet (7 meters) to 16 and a half feet (5 meters). Scientists think that it may be because of over fishing in Eastern Asian countries.

The Whale Shark is listed as vulnerable under the IUCN Red List, but researchers are finding very disturbing facts.

Eco-tourism companies offering diving tours off of the North-West coast of Australia are noticing the decline in size of the Whale Sharks. They catalogue all the Whale Sharks, including length, weight, sex and so forth.

Mark Meekan of the Australian Institute of Marine Science (AIMS) says that this is a very worrying sign. Since the sharks don't sexually mature until around 19 and a half (6 meters) to 23 feet (7 meters), this is cause for worry.

Whale Sharks, like all sharks, take a long time to mature, and have very few offspring every year. And, like all sharks, they are very susceptible to over fishing. This has become a serious problem for almost every single shark that nears the surface, Fishermen don't take the time to consider how bad it would be on the population. I don't mean small time fishermen that take only a few, I mean commercial fishermen, that take hundreds. What's even worse is shark finning. This horrid act is when the fishermen will cut off the sharks fins and throw the body back into the ocean, usually while the shark is still alive.

Shark finning happens because fishermen can make a lot more money doing it. Since they only have a limited amount of space and the fins are worth more money than the whole body, it is much better for them to cut off the fins, and throw away the rest of the body. This, of course, is killing of thousands of sharks a day.

What makes it even worse is the fact that sharks do not have swim bladders, so, when they die, they do not float, they just sink to the bottom. If they did have swim bladders, the ocean surface would be absolutely littered with shark carcasses.

Back to the Whale Sharks.

Scientists think that the Whale Sharks are decreasing in size because of the amount of larger ones being caught. Researchers from AIMS are now tagging and cataloging Whale Sharks. They see them traveling from Australia to Eastern Asia, where some of them show up on land, leading them to believe that the sharks were caught and the tags removed.

They are trying to find out key areas where Whale Sharks congregate, in a hope to help protect the species further.

The BBC

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