by Melissa Krenke
For more than 400 million years, sharks have ruled the world’s oceans. Powerful and graceful hunters, these top predators are a crucial key to structuring the composition of many fish communities, and their loss would most likely be catastrophic to coral reefs worldwide. Yet, nearly all existing shark species are threatened by increasing international demand for their meat and unregulated fishing practices.
Rachel Graham, a marine scientist with the U.S.-based Wildlife Conservation Society, is working in southern Belize to better understand the current status of shark and ray populations in the Mesoamerican Barrier Reef by collecting baseline data and gathering historical accounts from local fishermen. Her overall goal is to encourage the Belizean government to develop shark and ray-specific management plans that help to ensure the species’ continued survival.
With funding from the National Fish and Wildlife Foundation’s Coral Reef Conservation Fund, Graham enlisted local NGOs and fishermen to help gather information about shark and ray species diversity, relative abundances, location of critical habitats, and movement patterns and measured their historical decline through surveys with shark fishermen.
Her findings are a cause for concern. Based on interviews with fishers, she has identified dramatic declines in the abundance of several shark species present in southern Belizean waters. Although catch rates were low, the species caught in the greatest abundance was the nurse shark (Ginglymostoma cirratum), followed by the Caribbean reef shark (Carcharhinus perezi), the blacktip shark (Carcharhinus limbatus), and the Caribbean sharpnose shark (Rhizoprionodon porosus). Of the ray species captured, the longnose stingray (Dasyatis guttata) was the most abundant, followed by the southern stingray (Dasyatis americana).
“The majority of the sharks that we caught were immature, and based on the comparison of our findings with information from local fishers, we detected shifts in species dominance, where certain species used to be found in one habitat, but have disappeared and been replaced by other species,” Graham explains. She also found strong evidence of shifts down the food web in the types of shark and ray species that are caught, from preferred species like the hammerhead (Sphyrna spp.) and blacktip sharks, to nurse sharks and rays, both of which were never previously exploited.
The shift to nurse sharks and rays is also of concern to local dive operators, as both species provide great underwater visuals and encounter experiences for snorkelers and scuba divers. Graham conducted a survey with local dive operators and found that the majority of them believe that sharks are very important to the tourism industry, that shark populations are declining, and they are worried about the lack of formal management and protection.
Graham’s work also identified critical shark and ray habitat, some of which is located inside Belize’s several marine protected areas. These areas are managed by local NGOs in partnership with the Department of Fisheries or the Department of Forestry, which diligently protect the fish stocks from threats such as the use of gill nets, illegal fishing, over-fishing, and capture of immature fish. This can be a challenge, as the areas the conservationists have to patrol is very large, and resources are limited. Further, most illegal fishing happens at night, and there have been instances of patrolmen encountering armed fishermen.
Declared a reserve in 2000, the 160 square-mile Port Honduras Marine Reserve is managed by Toledo Institute for Development and the Environment (TIDE). From December of 2006 through February of 2007, TIDE rangers reported increased shark fishing activities within the reserve, in response to the annual massive rise in demand for shark meat during the Lenten season. After the unused remains of hundreds of dead sharks were discovered, Graham was called in to assess the situation in the reserve. She discovered that 15 sharks had been caught in one day, including a blacktip shark that was within days of giving birth to three offspring, called pups. She also found six large barrels full of salted shark meat; it has been estimated that one barrel can hold the accumulated meat of up to 300 sharks.
A TIDE ranger reports, “When we approached these fishermen, they expressed that they were aware of the rules and regulations governing the reserve and claimed to be following them. For example, they were not using nets and long-lines in the reserve. However, they did not know about that hammerhead sharks are a globally endangered species. We were able to pressure them to leave, but they just went to another area in Belize. Their profit is too high, so they will not give up their livelihood — even if it is wiping out our sharks.”
An additional problem is that many illegal fishermen hold false Belizean fishing licenses to gain access to the country’s rich fish stocks. Therefore, when they are apprehended and handed over to government authorities, they are released and their gear is returned. “It is disheartening for us to patrol the reserve when there are so many non-Belizeans with Belizean fishing licenses indiscriminately wiping out all of our marine resources,” the TIDE ranger says. “The licenses they hold are illegal and false, but so far we have had no way of stopping them.”
In spite of such daunting challenges, a positive note is that many Belizean fishermen have become champions of more sustainable fishing practices. By employing fishermen to help collect data, Graham’s project provided an alternative source of income and also helped her to gain invaluable data by tapping into the fishermen’s historical knowledge of former abundances, habitats, and trends in the fishing industry. She points out, “When you add scientific doctorates to ‘PhD’s of the sea’, it is quite a formidable combination.” The biologist is pleased that her project has also helped to increase fishers’ range of skills and understanding of fish biology and sustainability issues; some have gone on to work with other research projects, and others have given up fishing altogether.
“Sometimes fishermen insist that I want to shut down the whole fishing industry — which is not the case — and the men I work with will sit down and talk to them about what we are trying to do, our findings in the field, and how valuable some of these top predators are in keeping the sea’s fish communities in healthy balance,” she notes, adding, “It doesn’t get much better than that.”
Graham now plans to incorporate her project’s data into Belize’s National Action Plan for Sharks, to be prepared for submission to the United Nations’ Food and Agriculture Organization (FAO). A FAO requirement for all countries that commercially catch sharks, the plan is a tool to help assess the current status of sharks worldwide and develop a management plan for maintaining sustainable shark populations.
“I’m looking forward to seeing specific management action for sharks and rays in the near future,” Graham emphasizes. “We’re using the best tools we have available — numbers — and if we can keep engaging local people, fishermen, and NGOs, then we have a much better chance of success.” Her findings have already been incorporated into the management plans of Belize’s Blue Hole National Park and the Half Moon Cay Natural Monument, and she aims to include them as many management plans, international publications, and conferences as possible to raise awareness on the plight and conservation needs of the Mesoamerican Barrier Reef’s top predators.