Two tiger sharks (scientific name: Galeocerdo cuvier) were found and tagged in Tubbataha Reef in the Philippines during a recent research expedition, the Tubbataha Management Office said.
Researchers from the Large Marine Vertebrates Project – Philippines (LAMAVE) and the TMO tagged the two during an expedition from June 11 to 19.
According to the TMO, the tiger sharks, listed as Near Threatened (NT) in the IUCN Red List of Threatened Species, were caught in the South Atoll off the Delsan Wreck dive site.
“Both of the tags are expected to produce information on the location and movement of the sharks. These information will be useful in understanding the dynamics of how the sharks use Tubbataha as a habitat, their range, and the potential areas of concern in the protection of the species,” TMO said.
It said the tiger sharks were caught using a baited fishing line about 60 meters deep with a barbless hook at the end.
Both captured tiger sharks measured more than three meters long and were estimated to weigh more than 340 kilos.
LAMAVE–Philippines’ Dr. Alessandro Ponzo placed an acoustic tag in one of the tiger sharks. The tag will ping three acoustic receivers in different spots around the park.
Meanwhile, a fin-mount tag was installed on the dorsal fin of the second tiger shark. The fin-mount tag will send signals to a nearby satellite once the tagged tiger shark surfaces anywhere in the world.
Also, the researchers collected tissue samples from the tiger sharks’ pelvic fins, for genetic connectivity studies to contribute to an ongoing global research on sharks.
Visible parasites were also removed and collected while the sharks were measured and their gender verified before being released.
“All of the sharks showed normal activity after release as great efforts were made to reduce the stress of the animals during the procedure,” the TMO said.
TMO said the team also carried out Underwater Visual Surveys (UVS) for elasmobranchs or the subclass of fishes where sharks and rays belong.
Last year’s UVS revealed that Tubbataha has the highest density of whitetip reef and grey reef sharks in the world.