Friday, 7 November 2014

Protecting long-haul sharks

The Blowfish
Hi sharky peeps! It’s me, The Blowfish, back again to speak to you about the secret ways of the sharks and rays. The Shark Trust is once again fighting the best fight for the toothy, finny elasmobranchs under the waves. So, what are we looking into this time round then?

Today we are going to talk about those sharks and rays that are always on the move. Now at first it might seem a great idea for sharks to always move around, but it can make it a nightmare for us conservationists to protect them if we don’t know where they are heading.

Whale Shark © Klaus Stiefel
So which sharks are highly migratory? We know that Whale Sharks swim the world’s oceans looking for the perfect plankton, Blue Sharks have been shown to travel 9200km and there has been some amazing work done recently satellite tagging White Sharks and other sharks to track their movements across the globe. However, we still do not know enough about the routes taken by sharks, what factors might make them migrate or even, where they go along the way. Take the Basking Shark: we get a brief glimpse of the world’s second largest fish from May till October, then poof!!! Vanished!!

The truth of the matter is we still have lots of research to conduct on these highly migratory animals. Tagging and tracking sharks is hard work, and not just due to the large cost of satellite tags – many tags need to wash up first, and then be found and uploaded on to a computer. Even simple numbered tags need to be reported to the correct organisation to be recorded. It’s a sad thought that many tagged sharks might be finned at sea and the tag – and all its amazing information – lost without trace.

So how do sharks manage to navigate all over the world?
Blue Shark © Terry Goss.

The ampullae of Lorenzini have long been considered the GPS of the shark and ray world. Being able to pick up the electromagnetic fields of living animals, it is widely believed that the ampullae also can detect the earth’s magnetic field and thus guide a shark across oceans. Sharks and rays must also have a great sense of timing though, as Whale Sharks are known to visit Christmas Island at a specific time each year to feast on the eggs spawned by the population of crabs found there.

So we get to the real problem with these footloose (or should that be fin loose?) sharks. How can we protect them if we do not know where they are? Well it is hard. Really hard. You basically need to get every country to agree to protect the sharks that enter their waters AND get that same country to actually uphold the agreement. Thankfully some of the best shark boffins in the world are coming together to talk about all this at the Convention on the Conservation of Migratory Species of Wild Animals (CMS) in Ecuador this November.

So keep your eyes peeled for some new developments and hopefully some solutions for the long-haul sharks and round-trip ray.

➤ Find out more about sharks at the Pups Activity Zone

➤ Visit the Shark Trust website

Visit the Blowfish website

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