Sharks are threatened worldwide due to unsustainable levels of fishing and other human disturbances. Exploitation of sharks has increased dramatically due to declining catch rates in traditional fisheries and an increasing demand for shark fins in Asian markets. The recent economic boom in Asia has led to a rapid increase in demand for shark fin soup, a dish that is considered a status symbol and a sign of wealth amongst many eastern cultures. The disproportionate value of the fins compared to the rest of the shark has led to the wasteful practice of fining whereby the fins of the shark are removed and the majority of the carcass is discarded, often while still alive. This brutal and wasteful practice is illegal in many territorial waters however it is commonplace in the unregulated waters of the high seas. The high demand in Asia has led to a rapid escalation in direct and indirect shark fisheries all over the globe. Recent research estimates that 1.7 million tones are harvested each year however the figure could be as high as 2.29 million tones, roughly equaling 73 million individual sharks. Further studies estimate that the total number of sharks in the north Atlantic has declined by two thirds in the last fifty years and the global biomass of sharks has declined 80% since the industrialization of fishing.
The high fishing pressure on shark stocks is exacerbated by their life history characteristics that make some species especially vulnerable to anthropogenic pressures including fishing and habitat destruction. Slow growth rates, late age at maturity, low fecundity, and low natural mortality, all lead to slow rates of recovery for sharks following dramatic declines in populations. Current declines in shark populations are also having wide reaching effects throughout marine ecosystems. General scientific consensus suggests that most marine food webs are subjected to top down control and consequently the effects of apex predator removal cascades through the trophic pyramid affecting the abundance of other species. For example, recent studies suggests that the over fishing of sharks is directly responsible for the decline of a centaury old scallop fishery on the east coast of the USA. Declines in shark populations have also been implicated in the reduction of herbivorous fish species on coral reefs leading to excess algal growth.
The Bahamas offers a fairly unique juxtaposition to the global predicament of sharks. Long line fishing has been banned since 1993 and as a result there is no commercial Bahamian shark fishery. The last recorded export of sharks from The Bahamas was two metric tons in 2004, thus the long line ban has effectively made The Bahamas a shark ‘no-take-zone’. Despite the absence of a commercial shark fishery in The Bahamas, sharks are still under threat due to the transboundary nature of many stocks. Species such as tiger sharks, bull sharks and oceanic white tip sharks are thought to make long migrations into the waters of other nations or the high seas where they are not protected. As a result many species of Bahamian sharks are becoming depleted despite the long line ban. Other anthropogenic factors such as coastal development are also likely affecting shark populations in The Bahamas. For example, recent tourism developments on the island of Bimini have resulted in major ecological impacts due to widespread dredging, sand mining, and mangrove removal. These habitats are critical nursery areas for juvenile lemon sharks and consequently their destruction has severely restricted the recruitment of juvenile lemon sharks into the surrounding waters.
Taking into account the local, regional, and global threats to sharks, the Cape Eleuthera Institute’s shark research project was developed to increase the capacity of basic and applied shark research and conservation in The Bahamas. One component of our research is addressing the spatial and temporal movement patterns of several species of sharks; a first step toward addressing the conservation needs of species that likely transcend many different coastal habitats and political boundaries. By identifying when and where Bahamian sharks are being targeted, international conservation and management plans can be developed. Quantifying spatial and temporal movement patterns of sharks will also allow us to determine critical habitats for different life stages, which in turn will be useful for the creation of sustainable coastal development plans and regulations. Our research methods include the use of baited underwater video surveys developed by the Australian Institute of Marine Science as a non-destructive method for monitoring shark populations (as opposed to long-lining). Baited underwater video surveys are also being coupled with passive and active tagging (acoustic telemetry) to follow the movements of individual sharks in the waters off Eleuthera. This work is supported by the Save Our Seas Foundation and conducted in collaboration with Mote Marine Laboratory, The Marine Biological Association of the United Kingdom, and the University of Plymouth.
The Cape Eleuthera Institute is proud to support the mission of The Shark Trust to promote the study, management and conservation of elasmobranchs.
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