Great hammerhead sharks have been tagged and tracked across the USA and Bahamas in an effort to shed light on their migration habits. iStock/Shane Gross

North American scuba divers thrill at the sight of schooling hammerhead sharks in places like Cocos, the Galapagos and Malpelo. But a little closer to home, in Bimini, Bahamas, scientists at the Bimini Biological Research Station are uncovering new information on the migration patterns of the great hammerhead shark, Sphyrna mokarran, which they believe will lead to better protection of this endangered species. A target of both the recreational fishing and shark-fin trade, the global population of the instantly recognizable great hammerhead shark is estimated to have declined by more than 80 percent over the last 25 years.

Scientists at the Bimini Biological Research Station in the Bahamas use a non-invasive technique to estimate the size of sensitive animals, such as the great hammerhead shark. iStock/Shane Gross

The great hammerhead has been listed by the IUCN as endangered since 2007. It has also recently been included in CITES Appendix II, which regulates the international trade of threatened species. Despite its threatened status, effective protection and management has so far been hampered by a lack of information about the shark's behavior. However, new research published in the journal Frontiers in Marine Science, offers some hope for developing better conservation methods. By identifying the sharks' use of particular areas, marine management and conservation officials can hopefully limit the sharks' interaction with humans, who pose the biggest threat to their long-term survival. Dr. Tristan Guttridge, who led the study at the Bimini Biological Research Station, explains why this is so vital: "Knowing when the animals are likely to be in certain places will be critical in developing effective management strategies," he said. "For example, our data could be used to create so-called 'time-area closures,' where certain areas are closed to particular activities, like fishing, at different times. The aim would be to reduce harmful interactions with the sharks." Dr. Charlie Huveneers of the Southern Shark Ecology Group in Flinders University, Australia, agrees. "New information about movements of great hammerheads will help managers and regulators to ensure sustainable catches, and to improve international regulation and management," he said. "Thanks to the combination of methods used by the authors, the study has revealed complex movement patterns, with broad-scale migrations across jurisdictions as far North as Virginia, USA, as well as seasonal site fidelity in Florida and the Bahamas."

The bottom line: the endangered great hammerhead shark is in desperate need of effective conservation management. iStock/Shane Gross