Silky shark tagged in Galapagos is detected at Clipperton Atoll

May 17th, 2011

A silky shark tagged at the Galapagos Islands migrates north to Clipperton, setting a new migration record for the region of over 2200 kilometers.

A silky shark tagged in Galapagos migrated to Clipperton

The Charles Darwin Foundation (CDF), a founding member of the Migramar network of scientists focused on the Eastern Tropical Pacific (ETP), and the Mexico-based research group, Pelagios, have identified a new shark migration record for this oceanic region.

In April, the Pelagios team found records of a silky shark (Carcharhinus falciformis) in the surrounding waters of Clipperton Island, 2200 km distant from its tagging location at Wolf Island in the Galapagos Marine Reserve (GMR). This charts the current record for shark migration in the Eastern Tropical Pacific monitored by the Migramar network.

The record-setting female silky shark, measuring approximately 1.9 meters in total length, was tagged with an ultrasonic chip in the Wolf Island anchorage in March of 2010. The shark remained in GMR waters for approximately two months where it was last detected on May 1, 2010. Since then, its whereabouts remained unknown until its September 18, 2010 detection off Clipperton Island, where it remained for one month. These appearances were recorded via ultrasonic receivers placed by Migramar throughout the ETP.

Ongoing for four years, the shark-tagging project in Galapagos is a joint program of the CDF, the Galapagos National Park (GNP) and the University of California-Davis. It facilitates the capture of biological and ecological data to enhance conservation of ETP pelagic biodiversity. Among the species currently under investigation are whale sharks (Rhincodon typus), hammerhead sharks (Sphyrna lewini), Galapagos sharks (Carcharhinus galapagensis), silky sharks (Carcharhinus falciformis), and black-tip sharks (Carcharhinus limbatus).

Although this individual is the only one of its species to be tagged thus far, its Clipperton registry supports the theory of a shark migration corridor within the Eastern Tropical Pacific. The Migramar network has successfully tracked the movements of hammerhead sharks between the Galapagos, Cocos and Malpelo islands in the heart of the ETP, but never before outside this zone. It is postulated that Clipperton Island serves as a midway resting place for pelagic fish along their migratory routes between the northern and central ETP. Clipperton Island is the only coral atoll in the ETP and is located approximately 1100 km from Tejupan, Michoacan, Mexico. It is a French possession administered by French Polynesia.