Scientists observe ‘decline’ in reef sharks population worldwide

A study made by Global Finprint published in Nature on Wednesday, July 22, revealed that 20 percent of reefs surveyed had no reef shark populations, indicating a “widespread decline” of the iconic species worldwide.

According to the Large Marine Vertebrates Research Institute Philippines (Lamave) and Global FinPrint project, 371 reefs were observed in 58 countries for the study.

The groups said that this means that reef sharks are “functionally extinct” in these areas, or too rare to perform their normal roles in the ecosystem.

Lamave executive director Sally Snow said that there were no shark sightings in the waters surrounding the islands of Cagayancillo, Cawili, Arena in Palawan; Ticao island in Masbate; Matnog town in Sorsogon; and Sablayan in Mindoro Occidental during the survey period.

In the marine protected areas of Tubbataha Reefs Natural Park and World Heritage Site, and Apo Reef Natural Park, meanwhile, reef sharks were sighted.

Ryan Murray, lead researcher for Lamave, said that while the future of reef sharks in the Philippines is uncertain, “optimistic solutions” are still available.

“The recovery of reef sharks in the Philippines will require intervention from the government to establish large dedicated shark sanctuaries with strict enforcement policies and the implementation of sustainable fishing practices,” Murray said in a Lamave press release.

“However, both measures will require government investment to support alternative livelihood programs and capacity building for coastal fishing communities, which would help to ensure their cooperation and compliance.”

He said that the country can look at the Tubbataha Reefs Natural Park and Heritage Site as an example of governance and planning taking into consideration how these species thrive.

Outside the Philippines, no sharks were also observed in Dominican Republic, the French West Indies, Kenya, Vietnam, the Winward Dutch Antilles and Qatar.

Reef sharks, according to conservationists, are important food resources, tourism attraction, and top predators in the reefs around the world.

Dr. Mike Heithaus, Global FinPrint co-lead and dean of the College of Arts, Sciences and Education at Florida International University, said via a press conference thru Zoom on Tuesday that when losing big predators, ecosystems are disturbed.

“If you lose these sharks from these systems, you can destabilize the whole ecosystem and have negative impacts not just to nature, but also to fishermen and people that rely on it, especially in these coastal ecosystems that we study,” he said.

He said that they are still understanding just how important sharks are to coral reefs.

“We are trying to answer, ‘Do healthy reefs need sharks? Or do sharks need healthy reefs?’ But the FinPrint project gives us this first global baseline that is going to let us answer these really questions going into the future.”

Poor governance a factor

Global FinPrint noted that the loss of reef shark populations are due in part to poor governance.

“Although our study shows substantial negative human impacts on reef shark populations, it’s clear the central problem exists in the intersection between high human population densities, destructive fishing practices, and poor governance,” said Dr. Demian Chapman, Global FinPrint co-lead, during a Zoom press conference on Tuesday.

“We found that robust shark populations can exist alongside people when those people have the will, the means, and a plan to take conservation action.”

Chapman is also an associate professor in the Department of Biological Sciences and Institute of Environment at Florida International University.

Three management pathways

The group said that shark sanctuaries and large closures will help in the conservation efforts.

Chapman said that in communities where residents rely on shark fishing, especially where there are no other alternatives for fisherfolks, turning their locality into a shark sanctuary “would not work because it would be too big of an economic and employment impact.”

He, however, stressed that their study’s result showed that these communities’ situation could work by setting catch limits.

The group’s study showed that countries where strong, science-based management limiting the number of sharks that can be caught have working shark conservation programs.

Countries such as Australia, the Bahamas, the Federated States of Micronesia, French Polynesia, the Maldives, and the United States have a large number of reef shark populations.

Dalhousie University associate professor Dr. Aaron MacNeil, lead author of the Global FinPrint study, said that along setting catch limits, governments can restrict gear types, and implement national-scale bans on catches and trade to help repopulate reef sharks.

Global FinPrint is a data-collection and analysis program of the world’s populations of reef-associated sharks and rays, while Lamave is a non-profit non-governmental organization dedicated to the conservation of marine megafauna and their habitats in the Philippines.

Global FinPrint is the initiative of the Paul G. Allen Family Foundation by the philanthropists Jody Allen and Microsoft co-founder Paul G. Allen.