Their hands were starting to ache as they gripped onto the soaking wet rope that held the heavy metal frame precariously over a vibrant Reef system. “Slowly,” a voice called out to the research team as they hauled up the baited remote underwater video system (BRUVS) closer to the surface of the ocean. Only minutes ago it had been sitting on the seafloor, recording the species of marine fauna in the area that are attracted to the bait attached to the extended arm in front of two video cameras. As the BRUV broke through surface, scientists scrambled to grab it before it banged against the side of their boat and carefully placed it on the vessel’s floor.

Done.

Within Glover’s Reef is a shallow lagoon with over 700 patch reefs, and these are protected by a marine protected area (MPA) here. One would think that a “protected area” would be a fully safe haven for the animals that call it home. Yet this research team has shown that even in protected areas, endangered sharks may still be vulnerable. Published in the Marine Ecology Progress Series journal, this is one of the first long-term monitoring studies of reef sharks within a marine protected area (MPA).

Carcharhinus perezi) populations were doing well within the MPA from 2001 to 2013. Then, their numbers started to dwindle. When examining footage from the BRUVs, researchers could normally spot several Caribbean reef sharks at a time. As the most common shark on or near coral reefs in the Caribbean, this made sense.

What didn’t make sense was that by 2018, they saw none on the video footage. The team documented their population decline between 2009-2019. Flowers points out it could be possible sharks were somewhere else in the MPA and didn’t pass by the cameras. However, this trend is still cause for concern. Caribbean reef sharks are listed as endangered by the International Union for the Conservation of Nature Red List of Threatened Species and research by FIU Ph.D. candidate Jessica Quinlan shows they are also one of the most fished shark species in Belize.

Well-designed MPAs are one conservation method that helps protect reef sharks (see WWF’s “A Practical Guide to the Effective Design and Management of MPAs for Sharks and Rays” here). But their effectiveness depends on their enforcement. “Once a marine protected area is implemented, they aren’t often monitored. Our findings are a call to action and stress the importance of monitoring population trends over time,” said lead author Flowers. “MPAs can’t be created and then ignored, because management measures that might work at one time may not work later due to changing socioeconomic and environmental conditions.”

Not to mention that sharks don’t know where boundaries of MPAs begin and end! Although Caribbean reef sharks mainly inhabits shallow waters, they have been recorded to reach depths to at least 98 feet (30 m) and are known to be bottom-dwelling species of the continental and insular shelves. That means they can frequent or visit areas beyond a no-take zone… right into dangerous waters. In this case, the researchers do believe fishing along the edge of the MPA could have contributed to the decline of Caribbean reef sharks.

The scientists shared this data with the National Shark Working Group — a team made up of government officials, shark fisherfolk, non-governmental organizations, and scientists. The group made recommendations that led to new legislation prohibiting shark fishing two miles around Glover’s Reef Atoll, Lighthouse Reef Atoll, and Turneffe Atoll. “You can think of MPAs like a garden. You don’t plant a garden and walk away. You have to tend it,” Chapman said. “And that’s what we are helping the government of Belize do. We are helping them tend the garden.”

Thanks to this concrete evidence, the government in Belize quickly responded and plans to implement new management measures to further protect sharks. “We can only be successful in the effective conservation and management of our marine resources when policy and management benefit from sound science. The contribution from our partners at FIU, Mote Marine Laboratory and the University of Miami has been central to the declaration of the recent Shark MPAs, which along with other management measures has been embraced by fishers and managers as important for the long-term protection and viability of Belize’s shark populations,” said Beverly Wade, the policy and planning advisor for Belize’s Ministry of the Blue Economy and Civil Aviation.

While the news wasn’t all that good for the reef sharks, another Caribbean species seems to be doing okay! Nurse shark (Ginglymostoma cirratum) populations remained healthy and stable within the MPA, mainly because they tend to stay within the boundaries and are also a nationally protected species in Belize. Like other sharks in Belize waters, they will continue to be monitored. The research was supported by Earthwatch Institute, the Paul G. Allen Family Foundation, the Mays Family Foundation and the Roe Foundation.