A new landmark study published today in Nature by Global FinPrint, with support from Shedd Aquarium scientists, teens and volunteers and many other marine conservation organizations, reveals sharks are virtually absent on many of the world’s coral reefs, indicating they are too rare to fulfill their normal role in the ecosystem, otherwise referred to as “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.
The new study found that sharks were commonly observed in the highest abundance in locations such as The Bahamas, where Shedd Aquarium researchers have been studying shark populations and contributing resources and data to the global research collaboration. High shark abundance in The Bahamas is a result of some of the most progressive shark conservation measures like banning longline and gillnet fishing and designating its entire 243,000 square miles of territorial waters as a shark sanctuary. Whereas, 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.
“Shark populations are facing conservation issues that are on a global scale, and thus require a global research effort to properly understand them. This study was the first of its kind in terms of the global scope and required a monumental collaborative effort to achieve,” said Dr. Steve Kessel, director of marine research at Shedd Aquarium and one of the study’s authors. “Global FinPrint cannot be praise enough for their coordination of these efforts and we at the Shedd Aquarium have been honored to contribute to the study. We hope that this study not only provides crucial baseline data for the state of the world’s reef shark populations and highlights successful conservation approaches like those of The Bahamas, but also can serve as a blueprint for necessary future wildlife surveys on a global scale.”
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.
Over the course of four years, the team captured and analyzed 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 organized by a network of collaborators from Florida International University, the Australian Institute of Marine Science, Curtin University, Dalhousie University, and James Cook University.
As Shedd’s research team contributed videos from its focal research location, The Bahamas, Shedd volunteers and teens helped tackle the 15,000 hours of video footage—watching and analyzing 1,557 hours of video from their homes and the Shedd’s Teen Learning Lab. Shedd Volunteer Betty Goldberg was among the contributing volunteers, watching more than 840 hours of underwater footage alone.
"Helping watch Global FinPrint videos as a volunteer at Shedd Aquarium is a nice way to be involved in this global research endeavor and stay connected with the ocean even when we’re 800 miles from the nearest one,” said Goldberg. “Each video is a fascinating opportunity to peek into a moment in time, where we’re virtually transported underwater, coming face-to-face with aquatic animals like the focal species of sharks but also spotting yellowtail snappers, Nassau grouper, moray eels and more. I admire the field researchers and scientists who work tirelessly on this project and dedicate their careers to understanding sharks and ways to protect them.”
This first-ever benchmark for the status of reef sharks around the world, funded by the Paul G. Allen Family Foundation, 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 and their prey, with the single largest contributor being destructive fishing practices, such as the use of longlines and gillnets.
“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 destabilize 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.”
For more information and a new global interactive data-visualized map of the Global FinPrint survey results, visit https://globalfinprint.org.