The team at the RJ Dunlap Marine Conservation Program, based at the University of Miami, have been placing hydrophones around Tiger Beach, Grand Bahama. These allow them to track tiger sharks (Galeocerdo cuvier), once these have had a transmitter implanted within their abdomens. According to Dr. Neil Hammerschlag in an article on National Geographic’s Ocean Views page, the process requires a small incision that heals quickly, with the tag transmitting for up to 5 years.
The advantage of this type of tagging is that the tags can be picked up by any hydrophone, including ones that have been placed to study other species. This allows researchers to collaborate and share data, perhaps limiting the number of times that individual animals need to be tagged.
In this video, the shark seems to either sense the weak electric field in the hydrophone and investigates it by mouthing, or it could simply be that tiger sharks are inherently curious creatures and will often investigate novel objects in their environment. Dr. Hammerschlag comments:
“Given that their teeth and jaws are sensory structures, without hands, the tiger may have simply been examining the hydrophone (with its mouth). Since tiger sharks have the power and capability to bite through turtle shells, we are lucky that it was only an exploratory bite”, going on to say that “the receiver is fine and continues to collect data on sharks that swim by.”