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 Scientists from our local partners, the Charles Darwin Foundation (CDF) and Galapagos National Park Service (GNPS) recently returned from a trip to the northern part of the Galapagos Marine Reserve (GMR) to outfit sharks with various types of tags which will monitor shark movements. This new project will help ensure that these vulnerable emblems of the GMR are being sufficiently protected and managed.
The project focuses on three species: the scalloped hammerhead (Sphyrna lewini), the Galapagos shark (Carcharhinus galapagensis) and the whale shark (Rhincodon typus).
Diving from the GNPS vessel "Guadalupe River", were CDF scientists Alex Hearn and Patricia Zárate, with marine park ranger Harry Reyes. They were joined by three visiting scientists from the US: Dr. Pete Klimley, who pioneered shark research in the 1970's, James Ketchum, a Ph.D. student from University of California, Davis, and George Shillinger of the Stanford Tagging of Pacific Pelagics (TOPP).
According to Dr. Klimley, "We were amazed at the sheer abundance of hammerheads around Darwin and Wolf. It was truly an extraordinary sight to see so many individuals in such proximity and certainly provides an excellent opportunity to learn more about these species".
Between July 21 and 29, small ultrasonic tags were inserted behind the dorsal fins of 18 hammerheads and one whale shark by free divers using pole spears. Submarine receivers were placed in known shark 'hotspots' to record the presence of tagged individuals. The team will then obtain information regarding the movements of these animals around and between these hotspots. Similar receivers have already been placed in Cocos and Malpelo islands by scientists there, so movements of animals between the three oceanic UNESCO World Heritage sites will also be detected if they occur.
Additionally, 12 Galapagos sharks were caught by a local artisanal fisherman, Tito Franco. Using handlines, Franco brought the sharks on board so that the scientists could insert satellite and archival tags on the dorsal fin and above the pectoral fins respectively.
Galapagos sharks have never been studied in detail anywhere in their range of distribution. Moreover, three of the individuals were also fitted with ultrasonic tags, making them the first triple-tagged sharks in the world.
Later in the year, the information from the receivers will be retrieved and analyzed jointly with the satellite data to provide the first information on shark movements in the GMR. This data will be used as a basis for a proposal for a wider study with far reaching conservation management implications.
Further work on the conservation of sharks in Galapagos is required. For example, there is virtually no information known about Hammerhead shark populations in Galapagos. We don't know the actual situation, but dive guides believe that Hammerhead populations have dropped in the last decade and illegally-fished shark fins have been seized. It is illegal to fish for sharks in the Galapagos Marine Reserve, but fishers from outside of Galapagos illegally come into the Marine Reserve to catch sharks in nets, cut off their fins and leave the sharks to die in the water. Shark fins sell for approximately $40 per set of fins.
Contact: comments@galapagos.org
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