Doubling Up On Reef Shark Conservation

All DC islands

Marine protected areas (MPAs), areas that provide legal protection to important marine and coastal ecosystems, often have more reef sharks compared to non-protected areas, but according to a new study in Nature Ecology and Evolution by researchers of Curtin University, Mote Marine Laboratory, Wageningen Marine Research, and others, finds that when MPAs are established in nations that also limit shark fishing through catch limits or gear restrictions, conservation benefits are doubled.

Based on the world’s largest reef shark and ray survey, Global FinPrint, a project funded by The Paul G. Allen Family Foundation, these findings emphasize that nations should use both approaches (the use of MPAs and effective fisheries management) to rebuild reef shark populations, which have declined on average globally by 63%.

Caribbean Reef Shark. Photo credit: Elianne Dipp

A new element

“Previous studies have shown that fully protected areas – that is MPAs where all fishing is prohibited – can benefit reef sharks. Our study adds a new element; nations can boost these benefits even further,” said Jordan Goetze, the study’s lead author, and Adjunct Research Fellow at Curtin University. “They can do so by applying restrictions on destructive fishing gear such as longlines and gillnets or limiting shark catches outside the protected areas. These actions reduce shark mortality across the whole nation and supercharge the effect of fully protected areas”.

More than 20,000 hours of video footage from 58 countries

The study used baited underwater video stations (BRUVS), which are cameras placed in front of a bait source on a reef for 60 minutes. Global FinPrint amassed over 20,000 hours of video footage across 58 nations, which trained researchers scoured for reef sharks to identity population abundance of various species on reefs. Previous analyses of these data highlighted alarming trends: reef sharks were functionally extinct on close to 20% of surveyed reefs and there was an average global decline of 63% across five main reef shark species (grey reef, Caribbean reef, whitetip reef, blacktip reef, and nurse sharks).

Impacts effective fisheries management

Reef shark sightings were on average twice as common in fully protected areas than nearby fished areas, yet the team also found that many fully protected areas didn’t provide any measurable benefits for reef sharks.

“We found that successful fully protected areas were large and protected whole reefs, not just parts of a reef. If designed correctly, MPAs could even be successful in areas of high human pressure,” said Demian Chapman, Director of the Sharks and Rays Conservation Research Program and Lead Scientist of Global FinPrint.

Fully protected areas found to benefit reef sharks were located all over the world, including the U.S., Australia, Belize, Bahamas, Antigua and Barbuda, Cuba, Brazil, Indonesia, Malaysia, the Philippines, and Fiji.

The team compared reef shark sightings inside fully protected areas in nations that had fisheries management measures known to benefit reef sharks and in nations where shark fishing was not effectively controlled.

Hammerhead shark
Photo credit: Ben Phillips

Also benefit to widespread sharks

“It was clear that the best outcome for reef sharks occurred when nations used both fully protected areas and effective fisheries management together,” said Goetze. “An advantage of national fisheries management is that it also likely benefits wide-ranging sharks like tigers and hammerheads that we showed didn’t benefit from fully protected areas because they don’t stay in on the coral reefs for as long as the reef sharks.”

Caribbean Netherlands: partially protected reef and inadequate fisheries management

Researcher Twan Stoffers, who has been active in data collection and analysis in the project Global FinPrint in the Caribbean Netherlands, and co-author of the publication, notes that the reefs in the Caribbean Netherlands are mostly only partially protected. “The Yarari Shark and Marine Mammal Sanctuary is supposed to protect sharks on the BES islands, but for now remains mostly a paper protected area with no enforced regulations. Although there are small no-fishing zones, where sharks are theoretically protected from fisheries, outside these zones fishing is common. This study shows that protection outside these zones is also essential. Therefore, we are likely to see little effect of these zones/MPAs on the shark populations of the Caribbean Netherlands.”

Erwin Winter, researcher at Wageningen Marine Research and together with Stoffers involved as project co-leaders for the Caribbean Netherlands in the follow-up project Global FinPrint 2, highlights that only on Curaçao (Curaçao Marine Park – Oostpunt) is a significant positive effect of the MPA on reef shark numbers observed in the Caribbean Netherlands. “On other islands, especially Sint Maarten, there is a positive effect, but not statistically significant,” he notes. Winter stresses the overall inadequate fisheries management across all islands, which urgently needs improvement to ensure a safe environment for the sharks.

Iconic species

Reef sharks are iconic species that likely play an important role in coral reef ecology and in some areas benefit people as living tourism attractions. In some cultures, they are celebrated as embodiments of gods, guardians and protectors.

30×30 initiative

“Many nations are currently in the process of expanding their protected areas as part of the global 30 x 30 initiative, which aims to protect 30% of our oceans by 2030,” said Chapman. “This study provides guidance on how nations can expand their protected areas in a way that benefits these ecologically, culturally, and economically important reef sharks. It also highlights that these protected area expansion efforts need to work with national fisheries management efforts to ensure the conservation of as many species of sharks as possible”.

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