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The joint CEI and University of Illinois shark research team just returned from the second of four, 2 week field expeditions to a shallow bank known as “the bridge” that connects the southern tip of Eleuthera to the northern tip of Cat Island. The first expedition went out in November 2011. The historical project is re-creating a study from a dataset detailing the diversity and abundance of shark populations in The Bahamas that took place over 30 years ago. Back then it was conducted by Captain Steve Connett and the crew of the R/V Geronimo from St Georges, Rhode Island. The current study is conducting surveys identical to those performed by Captain Connett and his crew 33 years ago, and has already discovered some very interesting results. In the original dataset, 96 sharks from six species were captured during 25 scientific longline sets. In just 12 sets, we have already caught 84 sharks from three species! While the recent study has encountered a lower diversity of species, the species dominating the catch remains the same. In the original dataset, tiger sharks represented 54% of the catch, and Caribbean reef sharks represented 33%, however, in the modern surveys Caribbean reef sharks and tiger sharks appear to have switched places, representing 67% and 31% of the catch, respectively. This is especially interesting in relation to the Bahamian ban on longline fishing instated in the 1990s, as Caribbean reef sharks, which are thought to be less migratory in nature than tiger sharks, might be benefitting from the indirect protection. Conversely, tiger sharks are more migratory in nature, and the benefits of the ban may be more limited. These results are still preliminary but with two more expeditions planned for 2012 and 2013 a much clearer picture should evolve in by the end of the project.
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