Every day on a shark research boat is exciting, but hauling in a huge tiger shark (Galeocerdo cuvier) is definitely a once in a lifetime experience. At the start of February the shark team, led by Research Technician Christian Daniell, set one of their first longlines of the new year and caught the biggest female tiger shark that CEI has seen on a shallow water survey in over 2 years.
The longline was set just a few kilometers off the south-east of Cape Eleuthera. After a 90 minute soak time, the team began hauling the line and were excited to find 3 Caribbean reef sharks (Carcharinus perezi), each shark bigger than the previous one. The team measured, tagged and safely released these sharks and were feeling content with their work. However, they were not heading home any time soon – hooked on one of the last gangions was a huge female tiger shark, over 3 meters in length! They could not believe their luck but soon jumped into action and secured the giant shark to the side of the boat. The interns were in awe of the incredible creature but worked efficiently to measure and tag the shark and then release it quickly.
Large tiger sharks are commonly found across The Bahamas and the chance to see, or even dive with them, attracts many tourists and brings great revenue to the area. However, these migratory sharks tend to hunt in deep waters and are rarely seen this close to shore. CEI’s long term shark monitoring program uses mainly shallow water longlines and therefore tends to catch juveniles or smaller sharks. Over the past few years, CEI has caught and tagged many juvenile tiger sharks on its shallow water longlines but has not caught a mature tiger shark since the spring of 2014.
The measurements of this unexpected catch will be added to CEI’s long-term longline database but will also be used by Christian Daniell, Research Technician, who is currently collecting data for his independent project. Christian hopes to spend his time here comparing the populations of sharks between 2008 and now. He will use both longlines and Baited Remote Underwater Video Surveys (BRUVS) to collect data and compare it to those published in a 2011 study by Dr. Edd Brooks. This comparison is particularly interesting as it may indicate how the implementation of a shark sanctuary in The Bahamas in 2011 has affected shark populations around the Cape. It is hoped that this prohibition of shark fishing will have increased and diversified local shark populations, and will provide evidence to support protective legislation in other places across the world.