Tagged Sharks

Shark tagging is an important tool for scientists studying marine predators as well as understanding the movement of one of the least studied marine predators on Earth. Sharks travel longer distances than almost all other marine species; they also have the ability to reach the deepest depths of oceans, where few other animals can dive.

Marine biologists use satellite tagged sharks to monitor their migrations throughout the year by mapping out their migration routes, feeding areas, reproduction grounds (breeding) and the locations of young (nursery) sharks. Scientists gather the data from tracking and monitoring sharks to understand how sharks migrate through different types of ecosystems based on their own biological needs, such as food sources, water temperatures, other environmental factors and also to understand the effects of long-term human impacts, including commercial fishing, pressures and climate change, on shark populations.

While tagged sharks do not provide scientists with direct evidence of mating or birth events, satellite tracking does allow scientists to identify potential mating areas and locations where sharks may give birth to their young. When a shark returns to the same location(s) at the same time of year over multiple years, it provides scientists with insight into the shark’s reproductive behaviour.

In total, tagging sharks has greatly increased our knowledge of shark migration and shark behaviour. The data collected will assist scientists in developing better conservation plans, protecting critical shark habitats and improving shark population management in a rapidly changing ocean.

Scientists can choose among many kinds of tags to obtain the information they want during their research.

Sharks may have conventional tags, which are small plastic tags with an identification number. The researcher will need to recapture the tagged shark (when possible) to gather new information about that shark’s growth, movement between locations, etc., and its overall survival rate.
Acoustic tags emit acoustic signals that are detected by underwater receivers located in a variety of habitats, including reefs, bays, and coastal areas. The signal is received when a tagged shark passes by one of the receivers, and the location of that shark is recorded; this helps scientists to determine where sharks in those areas move to and how they use their surroundings.
Satellite tags can transmit data to orbiting satellites when the shark comes to the surface. Because the area covered by the data is very large, satellite tags are ideal for determining sharks’ migration routes and how they behave while swimming in the open ocean.
The Pop-off archival tags record additional information, including depth, temperature, etc., and the data are recorded for a predetermined period. At that point, the tag is designed to detach itself from the shark and float to the surface, where it sends all the collected data back to the researcher via satellite.

Overall, these different methods of tagging provide researchers with a greater understanding of both the short- and long-term movement patterns of sharks so that they may continue to learn more about shark behaviour, preferred habitats and how sharks react to changes in the marine environment.

Sharks are treated with care when tagged by scientists, who have an obligation to protect the animals from undue stress and injury. The scientist’s next step is to support the shark in such a way that the shark can be safely handled. A small tag, used to identify the shark, or a satellite tracking device, is attached to the dorsal fin of the shark (where they will cause the least amount of disturbance). While supporting the shark, the scientist takes note of three important measurements: the total length of the shark, the sex of the shark, and the species of the shark. The process of attaching a tag and taking these measurements should take no longer than five minutes, and once finished, the shark is returned to its natural environment, allowing the shark to recover at its own pace. Scientists working on certain research projects may also remove a small sample of blood or a small clipping from one of the shark’s fins. By analysing the genetic information and hormone levels contained in the sample, the scientist can gain a better understanding of the overall health of the shark, how different populations of sharks relate to each other, and what factors influence the reproduction of the shark, all while causing the shark no lasting harm.

The length of time that a shark tag will last depends on the type of technology (tag) used and the species of shark being studied.

• Although conventional tags may be attached to a shark for many years, the information they provide can only be accessed when the shark is recaptured, and the tag is retrieved from its body.
• The transmission of acoustic signals can range from approximately three to five years, depending on battery life and environmental factors.
• Satellite tags typically operate for about six to twelve months, after which they fall off, lose signal, or run out of battery power.

Data collected even with the shortest tagging durations are very valuable to scientists. Data have been used to determine previously unknown migration patterns, locate the most important breeding sites and find feeding hotspots used by sharks throughout the year.

Shark tracking is providing researchers with valuable information on the behaviour and movement patterns of sharks in the world’s oceans.

Tagged sharks are demonstrating a level of site fidelity for their feeding sites, returning to them on a yearly basis. By identifying the locations of birth (nursery) habitats for many species of female sharks, tagged shark data can be used to protect those areas. Species like the oceanic blacktip shark and the tiger shark have been found by tracking studies to travel significantly further than previously thought, even crossing an entire ocean basin. Additionally, the migration of sharks from protected waters to unprotected waters has shown the need for all shark conservation efforts to cross national boundaries to be successful and requires international coordination and cooperation.

Data from tagged sharks are being incorporated into global databases such as OBIS-SEAMAP and the Global Shark Movement Project to support research at the global scale, inform and develop policy, and advance shark conservation.

Methods of modern shark tagging were developed to minimize stress on sharks and to prevent long-term harm. The majority of shark tags are either applied externally or to cartilage areas that contain few nerve endings. After sharks are released, they usually rapidly return to their normal swimming and eating behaviors. Research teams closely monitor sharks tagged as part of this research study to determine if there are negative effects to the animal due to tagging, and to ensure no permanent injury has occurred. Long-term tracking data consistently demonstrate the normal movement patterns of tracked sharks, demonstrating successful recovery from the tagging procedure. Research teams conducting shark tagging studies adhere to strict ethical guidelines that prioritise the well-being of sharks while balancing the need for the scientific information required from these large and important predators of the world’s oceans.

There is no requirement for a research ship or a science degree to assist in the process of shark tagging and conservation; however, public participation will play a significant role in protecting sharks all around the world. Public assistance can be made through organisations that are actively studying and tracking sharks for conservation purposes, such as NOAA Fisheries and the Save Our Seas Foundation. These organisations provide funding for the various aspects of research, including tagging programs and long-term conservation initiatives.

When a diver or fisherman encounters a tagged shark, they may be able to provide helpful data by documenting the tag number, the location at which they saw the shark and taking photos if possible. Reporting this information will be a valuable source of data for scientists to determine how sharks migrate, how many survive, and what other conclusions can be drawn from the data collected.

Educational materials about sharks and tagging research can also have a positive impact on the community. By educating the public about sharks and their importance, it helps to diminish the fears people have toward these animals, increases the level of support for shark conservation and promotes environmentally friendly practices when participating in water activities. Each small contribution made by members of the public will add to the larger picture. As the public continues to participate in assisting with shark conservation efforts, the amount of data available to scientists will increase, the effectiveness of shark conservation methods will be improved, and the chances of endangered shark populations surviving over time will be increased.

Tagging of sharks is an important part of maintaining healthy shark populations as well as protecting the interests of people. By monitoring the migrations of sharks, researchers are able to learn about where and when sharks travel. This information provides valuable data for fisheries managers to better manage their resources and make more sustainable choices to preserve all of the ecosystem components of the world’s oceans.

Healthy shark populations play a critical role in maintaining balance in the world’s oceans. Sharks regulate prey species and support biodiversity. Healthy marine ecosystems will continue to provide us with a variety of benefits, such as food security, coastal protection, and other economic benefits from the ocean-based economy. Therefore, the use of research and tagging to protect sharks ultimately protects both the health of our oceans and human well-being.

For over a decade, Durban Shark Diving has provided its customers with educational opportunities for an experience of a lifetime through ocean adventures. We offer our shark cage diving experience in Durban allowing people to dive into the waters with oceanic blacktip sharks at close range, while assisting in local marine research and conservation efforts. Want to see these incredible animals in their natural habitat as well as see what it is like for the scientists who are working to help conserve them? Go to our home page to view the different tours.