While tracking via satellite may prove to be more costly than tagging, it is more effective and reliable in the long run. It provides accurate information regarding the movement and positioning of the animal, the speed it is swimming at and its preferred habitat within just a few hours of the real-time event.
It is possible for these researchers to follow and watch the tagged sharks at any time of the day or night. This is vital because increased knowledge and understanding means an increased ability to preserve these fascinating creatures as well as to maintain optimal marine biodiversity.
For the satellite device to be attached to the dorsal fin of the shark, the animal is lured close to the boat by the scientists: dangling a tasty morsel under the water’s surface or by catching the shark in a gill net. The shark is either lightly restrained, or is suspended alongside the boat using ropes. After being measured and weighed and having its sex determined, the satellite tracker is bolted to the dorsal fin in a plastic container, designed to ensure that water does not actually come into contact with the equipment.
The device needs to be as light in weight as possible, so that it does not interfere with the regular habits and processes of the animal.
The satellite transmitter attached to the shark should include long-life batteries, an aerial and the all-important transmitter itself. As the animal goes about its usual activities, completely unhindered by the device, the transmitter sends signals to a satellite, which then interprets the positioning and sends this information to a control centre anywhere in the world. The researchers are able to tell where the shark is, the path along which it has travelled and the speed it has reached.
Some transmitters have a saltwater switch, which ensures that the device is only enabled when the fin is raised out of the water and is switched off when it is submerged. This saves battery power and provides for a longer period of surveillance.
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