First-of-its-kind Global Survey Reveals Sharks are Functionally Extinct from Many Reefs

Global FinPrint, a Paul G. Allen Family Foundation initiative, finds that hope remains if key conservation measures are employed A new landmark study published in Nature by Global FinPrint reveals sharks are absent on many of the world’s coral reefs, indicating they are too rare to fulfil their normal role in the ecosystem, and have become “functionally extinct.” Of the 371 reefs surveyed in 58 countries, sharks were not observed on nearly 20 percent, indicating a widespread decline that has gone undocumented on this scale until now. Over the course of four years, the team captured and analysed more than 15,000 hours of video from surveys of 371 reefs in 58 countries, states and territories around the world. The work was conducted by hundreds of scientists, researchers, and conservationists and also identified conservation measures that could lead to recovery of these iconic predators. "While Global FinPrint results exposed a tragic loss of sharks from many of the world's reefs, it also shows us signs of hope," said Jody Allen, co-founder and chair of the Paul G. Allen Family Foundation. "The data collected from the first-ever worldwide survey of sharks on coral reefs can guide meaningful, long-term conservation plans for protecting the reef sharks that remain." MMU PhD student and co-author on the study Alexandra Watts and colleagues carried out the Mozambican fieldwork contributing to the study, where she has been a researcher with the Marine Megafauna Foundation (MMF) since 2015. ‘While it was discouraging to see the low abundance of sharks around Bazaruto, Mozambique, from areas previously known locally for their shark abundance such as ‘shark alley’, the study determined that this region has good potential for shark recovery given conservation interventions. This means future conservation actions by organisations such as MMF will be invaluable to restore shark presence to the area’. Essentially no sharks were detected on any of the reefs of six nations: the Dominican Republic, the French West Indies, Kenya, Vietnam, the Windward Dutch Antilles and Qatar. Among these, a total of only three sharks were observed on more than 800 survey hours. This benchmark for the status of reef sharks around the world reveals an alarming global loss of these iconic species that are important food resources, tourism attractions, and top predators on coral reefs. Their loss is due in large part to overfishing of sharks, with the single largest contributor being destructive fishing practices, such as the use of longlines and gill-nets. “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 and Associate Professor in the Department of Biological Sciences and Institute of Environment at Florida International University. “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.” The study revealed several countries where shark conservation is working and the specific actions that can work. The best performing nations compared to the average of their region included Australia, the Bahamas, the Federated States of Micronesia, French Polynesia, the Maldives, and the United States. These nations reflect key attributes that were found to be associated with higher populations of sharks: being generally well-governed, and either banning all shark fishing or having strong, science-based management limiting how many sharks can be caught. “These nations are seeing more sharks in their waters because they have demonstrated good governance on this issue,” said Dr. Aaron MacNeil, lead author of the Global FinPrint study and Associate Professor at Dalhousie University. “From restricting certain gear types and setting catch limits, to national-scale bans on catches and trade, we now have a clear picture of what can be done to limit catches of reef sharks throughout the tropics.” The FinPrint team is wrestling with the fact that conservation action on sharks alone can only go so far. Researchers are now looking at whether recovery of shark populations requires management of the wider ecosystem to ensure there are enough reef fish to feed these predators. “Now that the survey is complete, we are also investigating how the loss of sharks can destabilise reef ecosystems,” said Dr. Mike Heithaus, Global FinPrint co-lead and Dean of the College of Arts, Sciences & Education at Florida International University. “At a time when corals are struggling to survive in a changing climate, losing reef sharks could have dire long-term consequences for entire reef systems.” Launched in the summer of 2015, Global FinPrint’s data were generated from baited remote underwater video stations (BRUVS) that consist of a video camera placed in front of a standard amount of bait – a “Chum Cam.” Coral reef ecosystems were surveyed with BRUVS in four key geographic regions: The Indo-Pacific, Pacific, the Western Atlantic and the Western Indian Ocean. For more information on the work of Manchester Metropolitan University, check out the work of Alex and her colleagues on her page here and on twitter and the lab twitter. For more information and a new global interactive data-visualized map of the Global FinPrint survey results, visit globalfinprint.org.

© Ecological Genetics & Conservation, 2019