Saving sharks in decline
The decline of shark species in the last 50 years, attributed to increasing commercial fisheries has been well-documented, with a shocking third of oceanic shark species now at the brink of extinction. This is causing alarm among marine biologists the world over, and has spawned a wealth of research dedicated to uncovering the secrets of these mysterious animals. But many unanswered questions remain about these ancient species, which first appeared 420 million years ago, that need to be addressed to enable conservationists to recommend the protection they desperately need.
Dr Demian Chapman (School of Marine and Atmospheric Science, Stony Brook University, New York) and his team are in 2011 taking Earthwatch volunteers on an exciting and memorable expedition to the second largest barrier reef in the world, off the east coast of Central America in the vibrant and culturally rich country of Belize. They are attempting to prove to local communities and to the world that to survive, shark populations are in dire need of comprehensive networks of protected areas.
Marine biologists worldwide are alarmed at declining shark species.
Marine Protected Areas (MPAs) are being increasingly used as a management tool to preserve marine ecosystems and have proven benefits for a variety of reef species. Several studies now show that large mobile species of fish, such as sharks, exhibit high site fidelity (home ranging behaviour) especially during their early life stages, which increases the chances that marine reserves can really benefit them.
As apex predators that indicate the health of the marine environment as a whole, as well as being a major draw for dive tourism, the decline of shark populations has become an economic as well as an environmental problem for Belize. There are currently 13 MPAs in Belize, and the government is banning purse seining in their entire Exclusive Economic Zone, yet some MPAs still allow the damaging practices of long line and gillnet fishing. There is also a consistent problem with monitoring and enforcement in places. The Earthwatch team are hoping that results from this study will consolidate the existing marine reserve network and improve it over time, while simultaneously providing evidence that marine reserves in Belize are useful for shark conservation.
The Earthwatch project, Shark Conservation in Belize , which runs its first expedition this month, will use sophisticated underwater video technology to estimate the numbers of sharks inside the reserves at Glovers Reef, Southwater Caye and Turneffe Atoll in Belize.
Glovers Reef is a well-established marine reserve, whereas Turneffe Atoll is on the opposite end of the spectrum, renowned for being heavily fished. This will allow the scientists to make comparisons between the shark populations of fished and unfished sites, to provide evidence for the benefits of no-take marine reserves (where fishing is prohibited) for shark populations. Southwater Caye has recently been given marine reserve status, with fishing pressure only recently being halted, which should allow Dr Chapman and the team to collect baseline data at the start, and record the expected increase in sharks and their prey after fishing pressure is reduced and populations can recover. Several similar studies have already been carried out in Brazil and Australia, with results showing higher numbers of sharks occurring inside marine reserves.
A grouper explores the reef.
Assessing the ecosystem
Little is known about the ecological role of sharks in Caribbean coral reef ecosystems, but some modelling studies suggest that the loss of sharks from this ecosystem would cause ripple effects on the food web that could lead to a decline in coral - the very foundation of the reef. To address these concerns, a secondary aim of the project is to collect data relating to shark feeding habits. Sharks will be humanely captured by longline and dropline sampling methods, and released unharmed once the necessary data has been gathered. Non-invasive tissue samples will be collected from individuals of all the dominant shark species on the Belize Barrier Reef: Caribbean reef, nurse, Caribbean sharpnose, great hammerhead, blacktip, lemon, silky, night and tiger sharks. From these samples scientists can identify what prey items the shark has been feeding on. It is hypothesised that sharks inside the marine reserves will be feeding on larger-bodied fish prey than the same species living outside the marine reserves, as the protection from fishing in the reserves allows fish to live for longer and grow to larger sizes. If true, this would suggest that marine reserves provide richer foraging areas for sharks.
Spreading the message
One of the main objectives of the project is to raise awareness among local fishermen and students of the issues surrounding the decline of sharks, encouraging them to become involved in the project and ensure its sustainability for the future. Local scientists will be trained in the underwater video camera surveying technique, and be provided with the equipment and baseline data necessary to continue the project. There will also be a series of workshops, following on from those already established, to provide the managers of the marine reserves with the reports, papers, raw video data and outreach materials to enhance their capacity for raising awareness throughout Belize about the benefits of marine reserves.
The establishment of MPAs in Belize in the past has occurred with the input and co-operation of local fishermen and stakeholders, and this is key to the success of the project and for ensuring that results translate into action; it is important not only for the conservation of the threatened species, but for the livelihoods of the local communities who use ever-declining marine resources. By showing the connection between marine reserves and healthy shark populations, and the value of sharks for tourism, it is hoped that Belizeans will start to see the benefits of marine reserves for their own livelihoods.
One of the aims of the project is to raise awareness among local fishermen and students.
Preservation for the future
The sensitive habitats and diverse marine life of the Mesoamerican barrier reef makes Belize's coastline an ecologically important area, providing habitats for many threatened species such as hawksbill turtles, West Indian manatees and whale sharks. By proving that MPAs can support a larger number of sharks, as well as a richer diversity of prey species, Dr Chapman's work, made possible by the support of Earthwatch volunteers, can consolidate and enhance current efforts in Belize to create a comprehensive network of MPAs; reduce fishing pressure and prove to stakeholders and visitors to Belize the economic and intrinsic value of the marine environment.
Join Shark Conservation in Belize
as a volunteer.
Report by Sophie Thompson.