The trip to Playa Del Carmen, Mexico was a great success! We teamed up with Fins Attached and were able to deploy one Smart Position and Temperature (SPOT) tag and two internal acoustic tags. The data collected from these tags and future ones will be used to determine the migratory patterns of the bull sharks and ultimately find their birthing grounds. We hope to present this information to whomever controls those birthing grounds and work on getting those waters protected.
The diving was terrific and being able to observe bull sharks was a great experience. We saw tons of life! Here’s a short list of what we saw: African Pompanos (and other members of the Jack family), Southern Stingrays, Spotted Moray Eels, Lobsters, Spider Crabs, Loggerhead and Hawksbill Turtles, Remoras, a 0.5″ baby Scorpionfish, and of course the Bull Sharks. It was amazing to see how cautious the bull sharks were considering that they are one of the most aggressive types of shark. They were timid and clearly analyzed the situation. It is obvious that bull sharks do not blindly charge in, attacking whatever they see as much of the world believes. Our underwater attempts at tagging the bull sharks were unsuccessful as a result of their cautious behavior, yet I still gleaned a ton of experience and information though diving with them.
Because we were unable to attach an external acoustic tag, we were not able to complete the 24 hour exact tracking mission that we had planned. We were however, able to use the tracking equipment and learn how it works. Ben, Alex, I assisted Dr. Antoniou in setting up the sensor and I successfully navigated our boat to our classmates who were underwater with the tag attempting to attach it to a shark.
Tagging above the water was a different story. Two of the four days that we used a fishing boat we caught a shark. We split the team up into two boats and watched, filmed, or assisted in the attempts. Attaching the internal tags was a delicate process. The shark had to have an approximate five centimeter incision through the extremely thick muscle but not so far that the scalpel would penetrate the internal organs. Two blades broke while creating the incisions and it is always sad to see the shark have to bleed a little bit. Once the incision was made the internal acoustic tag was slid inside and the wound was stapled shut to aid the healing process, which is incredibly fast for sharks. On the second and smaller of the two sharks we attached the SPOT tag to the dorsal fin. In order for data to be collected, it had to be placed so that its antennae rose above the top of the fin. This had to be done on the side of the boat with the shark right-side-up in the water. We were not sure how difficult this would be, because sharks only go into tonic immobility when they are placed upside-down. Luckily this bull shark was extremely cooperative and gave us no troubles at all. We tagged her, measured her at just over six feet, and then sent her on her way. Later we decided on the name Sydnee for the shark because Sydnee was the only female student on the trip.
In the coming weeks, acoustic receptors will be set around Playa Del Carmen to pick up the movements of the two sharks we were able to tag. I hope to return next year to do some more tagging maybe even see one of our sharks again. It was a great trip and I truly enjoyed working with Fins Attached. I hope we are able to generate enough data soon in order to get the birthing grounds protected!