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Researchers prepare to tag and release a juvenile lemon shark on the line beneath their skiff.
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Nurse sharks were the order of the night, though we did catch one young lemon shark just as the sun was coming up. When hooked, sharks roll their bodies over and over, attempting to get free. After they calm, we accurately measure their length and sex, collect a small DNA sample, and then let them go. The young lemon finned along the surface as if to get a first look at the beautiful sunrise, and then dove for the safety of the Rocas reef.
When we came back aboard the Research Vessel SEWARD JOHNSON, all hands were busy in preparations for a change of location. The tides of Atol das Rocas are becoming unfavorable for the sharks of Lama Lagon, and therefore, for our work. We we steam to Fernando de Noronha (located 40 miles east of Atol das Rocas) this afternoon to study different sharks and a get little R&R. When the tides rise again with the next full moon, we'll come back to work with lemon sharks.
Fernando de Noronha, here we come! |
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Upcoming Caribbean Reef Shark Research at Fernando de Noronha |
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A Caribbean Reef shark slowly cruises past a line of snorkelers. |
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Caribbean Reef sharks (Carcharhinus perezi) disprove the old saying "the only good shark is a dead shark." As carcasses, they are worth only a few dollars to a fisherman. As living, swimming tourist attractions, however, each animal is worth several thousand dollars. In the Bahamas alone, some 40% of all dive packages include a baited Caribbean Reef shark dive.
Unlike lemon sharks (Negaprion brevirostris) Caribbean Reef sharks have never been the subject of dedicated scientific investigation. This presents a major problem for conservation planners who hope to protect the species and maintain the industry they support. Marine Protected areas are being developed around several Bahamian shark dive sites. However, we don't yet understand the movement patterns and population structure of this species -- Caribbean reef sharks might routinely "migrate" out of protected waters and therefore remain vulnerable to commercial fishing pressure.
During last year's Rocas expedition, scientific crew members Demian Chapman (Nova Southeastern University Oceanographic Center) and Ricardo Garla (University of Sao Paulo) noticed large numbers of newborn and juvenile reef sharks on the shallow reef surrounding the atoll. Unlike the young lemon sharks, which inhabit the shallow interior of Rocas, the young reef sharks swim brazenly in 30 feet of water, seemingly within easy reach of predators. Intrigued by this sighting, Garla and Chapman launched a collaborative program of research into the life history of these ecologically and economically important animals.
Funded by Nova Southeastern University, the University of Sao Paulo and Project AWARE, the project aims to characterize the movement patterns and population structure of the Caribbean reef shark in the tropical western Atlantic Ocean. This will involve monitoring the movements of sharks at Ferndo de Noronha, and genetic analysis of Caribbean reef sharks from different Bahamian islands, Belize, Atol das Rocas, and Fernando de Noronha. These results will clarify the degree of site attachment shown by individuals and populations of this species. This knowledge will help conservation planners develop an informed and effective management strategy.
Chapman and Garla will tag and DNA-sample Caribbean reef sharks caught incidentally on long lines and handlines set for lemon sharks. So far, fourteen Caribbean reef sharks have been captured, tagged, sampled and released. Most have been newborn animals -- an exciting discovery, since nursery habitats of the species are not well known.
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In choppy water, Kevin Feldheim works up a hooked baby Caribbean reef shark. DNA samples and catch data will be fed into Chapman and Garla's Project-AWARE-sponsored study of this species. |
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