Shark tracking is done by tagging and by satellite. There are some amazing apps and websites to track your favourite shark. Shark tracking and conservation is more important than ever because more and more shark species are becoming endangered but how do scientist do it?
Why Is Shark Tracking Necessary?
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.
How Do Scientists Track Sharks?
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.
How Does Shark Tracking Work?
Shark tracking is either done by tagging or by satellite. Underneath an explanation of both methods.
Shark Tracking With Tags
Tagging is the most common form of tracking sharks in the ocean. Tags are more affordable and accessible than satellite devices, they are easily visible and are relatively reliable. This process begins with catching a shark safely and responsibly. The animal needs to be restrained using as little force as possible to avoid trauma, exhaustion and subsequent death. The most common method, favoured by scientists, continues to be gill nets, which are characterised by a fine mesh for smaller sharks and slightly larger mesh for the bigger species. It is imperative that these nets are used properly, as they can prove fatal to the shark otherwise. The tag needs to be the right size for the shark too. Large, heavy tags will harm smaller sharks or juveniles, and an incorrectly applied tag can fall off (generating incorrect data) or even kill the animal.
The most popular form of tagging is the one that is administered by the use of a dart. This dart is placed in the base of the dorsal fin with a long cord, which has all of the capture information printed on it and is usually brightly coloured for easily identification. In addition, it should have the contact details of the person who originally caught and tagged the animal. Should someone catch and kill one of these tagged sharks, it is requested that they call the contact number and advise the person of this event in order to maintain accuracy in the research.
Some sharks are far too large or aggressive to be tagged without sending into a panicked frenzy or endangering the lives of the researchers. In these cases, Casey darts or a pole with a tag hooked onto the end of it is used. These hooks are then used to insert the tag into the base of the dorsal fin from a safe distance. This reduces the amount of struggling that the shark has to endure and results in a calmer, healthier specimen, suitable for re-release.
Should a fisherman catch a tagged shark, which is sometimes visible even under the water as a result of the neon colour of the tag’s cord, he would do well to record the following details and then report them back to the contact person on the tag (if at all possible, the fisherman should then release the shark):
- Tag number (leave the tag in the shark if it is strong and beable enough to survive release)
- Date of capture
- Specs (length, weight)
- Condition of the animal when released
- Location of capture
- Method used (nets, trawl, etc…)
- Boat name
- 1Home port
- Pictures (if possible)
If the shark was caught and killed, the same information would be necessary. However, the captor would then be advised to remove the tag for return to the original captor and to provide his own name and address for a reward.
Shark Tracking With Satellite
While shark 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.
Maps with images of the distribution and routes and even digital pictures generated by these receptors are all part of what satellite tracking enables scientists to gauge and use as material.
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.
Shark Tracker APP
OCEARCH is a shark research organisation that has been tagging and tracking sharks for over a decade. They have developed a shark tracker app that can be downloaded with android and IOS.
Download the OCEARCH shark tracker for IOS here.
Download the OCEARCH shark tracker for Android here.