Sharks have been an elusive and mysterious group of animals for centuries. There have been many theories, myths and tales about these predatory fish, but it is only in recent years that scientists and researchers have made headway with establishing concrete facts about such animals. These facts are vital for the protection and conservation of the many shark species, as well as to raise awareness amongst people, who are then better equipped to avoid attacks and preserve the marine environment.
There are hundreds of shark species, the majority of which live in the open ocean, sometimes reaching astounding depths. For this reason, they are not always easy to find. Therefore, tracking is essential, revealing to researchers their migratory patterns, life spans, measurements, population numbers and so on. This is essential as increased fishing is combined with a slow maturity process, meaning that human beings are killing more sharks than the animals are producing; the numbers are dwindling at an alarming rate and many species are now protected and endangered.
Working with the R/V Ocearch, DMF and Mote Marine Lab. scientists tag a
16 ft white shark with a real time satellite tag.
Sharks are tracked either via satellite or by a process called tagging. Both of these methods are somewhat traumatic for the animal as it needs to be caught and immobilised for a brief period of time. Captors need to ensure that their method of catching and tagging the shark is as non-invasive and has as little of a negative impact as possible. Otherwise, a weakened and traumatised shark will be released into the ocean with a strong possibility of death soon after its discharge. Should a tagged or tracked animal die, the data collected will be invalid and the population numbers inaccurate.
Both methods of tracking involve a small tag or device to be secured onto the shark. In the case of tagged animals, this tag or label will then contain information regarding the date of capture, size, sex, species and so on of the animal. It will be secured to the fish using a brightly coloured string or nylon so that future captors can see from a glance that it is a tagged animal.
When a satellite receptor is attached, it is to the dorsal fin, using a set of bolts to secure it. As the animal surfaces, data is conveyed. Most satellite tracking is very accurate as the delays are minimal (usually only a few hours).
Upon capture, fishermen or researchers need to assess the size and abilities of the particular specimen so that they do not attach a tag that is too large and heavy or too small, making it ineffectual. Some animals are small and calm enough to be brought onto the deck of the boat, while others will need to be tagged as they are suspended in the water. These factors, along with many more, make it essential that experienced taggers are involved in such projects. The alternative spells out major disasters in terms of the sharks’ survival rates.
For more information, please view: http://dsc.discovery.com/sharks/shark-tracking.html