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ULTRASONIC TAGS
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_13.jpgUsed in sea-floor detection, they last for up to two years. The blade rests under the shark's skin, in a layer of fat, and does not harm it.
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GETTING READY
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_12.jpgCésar Peñaherrera from the Charles Darwin Foundation (right) helps Eduardo Espinoza (left) with his tagging spear.
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A NEW BATCH IS READY TO GO
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_11.jpgThe tags are well looked after by a specialist assistant at the surface while the team tag the sharks below.
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TAG SPEAR
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_10.jpgJust before going in the water a small magnet is removed from the tag's side, initiating its ultrasonic broadcast.
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FREE DIVING
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_09.jpgTagging must be done in freedive, as bubbles from scuba equipment would scare the sharks.
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THE TAG
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_08.jpgThe spear accelerates towards the shark as an elastic is released. The shark is surprised and swims away, but soon goes back to typical behaviour.
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ULTRASOUND RECEIVER
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_07.jpgListening stations for the ultrasonic tags are located in strategic spots. The listening devices are designed for a life of months under ocean currents.
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ULTRASOUND RECEIVER
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_06.jpgWhen tagged sharks approach listening stations they leave a record of their presence.
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ON THE OCEAN FLOOR
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_05.jpgOr at least 40-50m down. The listening stations are regularly replaced to gather data. Old ones are cut free and new ones fastened into place.
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RECOVERING THE DEVICE
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_04.jpgThe listening devices, as almost everything else in the ocean, are quickly covered with life. A thorough cleaning is a good idea before extracting the data.
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NEW AND USED
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_03.jpgEven after cleaning, the erosion caused by sea water is easy to appreciate.
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SOFTWARE INTERFACE
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_02.jpgAs soon as the listening device is recovered, its data are extracted. The real, measured moments when the tags came close to the receiver are revealed for the first time.
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THE DATA ARE FINALLY PUT TOGETHER
http://migramar.org/hi/wp-content/uploads/2010/06/our_work_method_01_slideshow_01.jpgThe real significance comes when the data from all listening stations throughout the region are brought together.
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