Processes involved in Shark Tagging

  • A written description of shark tagging
  • A series of photos showing the process

  • In order to tag sharks you must catch them. A variety of equipment is used to catch sharks. When conducting research, scientists choose gear and procedures in order to help limit possible damage to sharks that could occur as the sharks are captured. The scientist's goal is to capture the shark, collect data, tag the shark, and return it to the ocean to live a healthy life. The most common gear used by scientists are gill nets which are 400 feet long (122m) and 10 feet (3.04m) high. The size of the mesh is selected according to the size of the sharks being caught. Smaller mesh is better for catching smaller sharks. When using gill nets, scientists are extremely careful to remove the sharks immediately, quickly collecting data and tagging the sharks, and returning them to the ocean. For tagging very large sharks, it is not possible to bring them out of the water, so they are tagged from the boat using a pole. Scientists at Mote Marine Laboratory have a special permit to use gill nets and are required by law to follow procedures that limit damage to sharks. Gill nets, if not used with special care, can cause damage to sharks or may kill them. Biologists are trained to tag sharks in specific ways that will not harm the shark or affect its movements. In recent years, fishermen have joined the efforts to collect data about sharks by tagging g sharks when they catch them, rather than killing or releasing them without tags. The fishermen who participate in these tag and release programs also need to be trained to use tags correctly. Tags improperly applied or placed in the wrong types of sharks can fall off, affecting stunt growth, creating inaccurate age and growth estimates. Improperly applied tags can even cause death. To prevent this, scientists have studied different types of tag design and technique in order to determine the best type of tag to use. The specific style and size of a tag can be matched to the shark being caught and released. For example, young or small adult sharks cannot handle tags designed for larger, tougher animals. Sharks are tagged at the base of their first dorsal fin. The most frequently used tag for sharks is the Dart tag which has a small dart connected to a cord about 8 inches long. Contact information and instructions for the person who recaptures the shark are printed on the cord. Sonic or radio tags are sometimes used as a way to track sharks continuously by sound, but these are expensive and only used in special studies. Casey tags are similar to dart tags except that they have a larger barb at the end. These tags are used less frequently than dart tags, and only for very large sharks. Very large sharks that cannot be brought on board a boat are tagged using a pole, which attaches the tag to the sharks first dorsal fin. Roto tags are an older design, less effective than dart tags and used rarely, since they are more awkward and bulky than dart tags.

    Photo documentation

    Unwinding The net is kept ready for use.
    The net is fed out the back of the boat. Letting the net
    Hauling-in Once the shark has been encircled, the net is hauled in
    Raising the shark into the boat once it's in the net is a tricky process. Netting
    Processing The shark is placed on a board to begin measuring and weighing
    The shark is bundled in a smaller net to make handling easier. Bundling
    Weighing The shark is hung in the net from a scale.
    The shark must be carefully handled to prevent it from thrashing around the boat. Handling
    Measuring The length is measured
    Spans between fins are measured. Other measurements
    Gathering data The various weights and measures are recorded.
    A durable tag is inserted into the dorsal fin that will identify this shark uniquely. Tagging
    Insertion Insertion of the barbed tag in the cartiledge of the dorsal fin.
    The sharks are released as quickly as possible to insure their well being. Release

  • Next: Try to predict where sharks will be and try to tag one.