Shark study kicks off at Sulu Sea’s Tubbataha Reefs

KORONADAL CITY (MindaNews / 20 July) – A study to further understand the behavior and population of sharks has commenced at the Tubbataha Reefs Natural Park (Tubbataha Reefs), a protected seascape that lies in the middle of Sulu Sea and forms part of the Coral Triangle, one of the most important reef systems in the world.

Tubbataha Reefs Natural Park has some of the highest density of reef sharks in the Coral Triangle. In the photo, 34 individual juvenile grey reef sharks were seen cruising the reef. Photo by David Choy / ASEAN Center for Biodiversity

Angelique Songco, protected area superintendent and head of the Tubbataha Management Office (TMO), confirmed they are conducting a survey on sharks given the dearth of knowledge about such species in the Tubbataha Reefs, which is a designated ASEAN Heritage Park.

With the support from the ASEAN Center for Biodiversity (ACB), she said the TMO, for the first time, is leading a shark survey at the Tubbataha Reefs following studies conducted by the Large Marine Vertebrates Research Institute Philippines (LAMAVE) from 2015 to 2017.

“The objective is to establish trends over the years and detect changes in shark abundance and species distribution,” Songco said in a statement issued over the weekend.

Songco explained that the shark survey will use the Underwater Visual Survey (UVS) method, a non-invasive and unbiased approach in which divers swim down the current for 40 minutes while identifying and counting passing sharks within an imaginary 30-meter transect strip. While the UVS has little to no effect on the behavior of sharks, the survey needs to be complemented with other techniques for a better understanding of shark ecology, she added.

Researchers and marine park rangers will conduct the survey with assistance from World Wildlife Fund for Nature (WWF) – Philippines, LAMAVE and local volunteers.

Unfair views

Perceived to be scary and ferocious monsters of the sea, sharks are unfairly viewed as dangerous to humans, ACB said.

These apex predators, however, play a functional role in the marine ecosystem maintaining the balance of the food chain, thus serving as a sign of the ocean’s good health, it added.

The previous studies on sharks recorded the presence of 23 species of sharks and rays in the Tubbataha Reefs, the non-profit stated.

Songco said that based on the movement tracking of the tiger sharks inside and outside the Tubbataha natural park, adults travel out of the park at the end of the summer and return there after a few months. ACB Executive Director Theresa Mundita Lim said that the shark study, along with lessons learned and further research activities in the park, may feed towards larger stakeholder efforts to enhance shark conservation measures at the national and regional levels.

Tubbataha Reefs. Map courtesy of Google

“We take note of the collaborative efforts among the government, non-government organizations and academic institutions to fill the knowledge gaps on sharks and other important species in the marine protected area,” she said.

There are 254 species of sharks and rays in the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species that can be found in the ASEAN, of which 140 are categorized as critically endangered, endangered and vulnerable, according to ACB.

Pristine site

For the Tubbataha Reefs, it covers roughly 10,000 hectares of coral reef at the heart of the Coral Triangle. This pristine site is home to a high density of marine species, including 700 species of fish, 13 species of dolphins and whales and over 100 species of waterbirds, data from the Tubbataha Management Office showed.

The information generated from the study will also be used to assess the effectiveness of the park management as sharks are one of its key biophysical indicators, ACB said.

The abundance of sharks has declined over the past decades with more than half of the 39 species now threatened with extinction, according to the IUCN.

Tubbataha Reefs is one of the last few remaining places in the Philippines where reef sharks thrive, attributed to the strict protection afforded to the park and sufficient area to support the movement of the apex predator. Songco noted, however, that local and global stressors such as fishery-related activities and climate change are ever-present threats to these predators.

Amid these threats, the continuous monitoring of shark abundance and species distribution, complemented by other shark studies, will help inform the park management and stakeholders on current trends and changes in the overall ecology of the sharks, she said, adding it will further help the management formulate effective shark conservation measures. (Bong S. Sarmiento / MindaNews)