From the Galapagos National Park Service

During a recent 12-day trip to Darwin and Wolf Islands in the north of the archipelago (only visited by dedicated scuba diving cruises - no land visits are possible here), technicians of the Galapagos National Park Service, with support from scientists of the Charles Darwin Foundation and the University of California Davis, managed to capture and mark eleven sharks of different species, as part of a shark monitoring program.  The idea is to understand the movement patterns of sharks within and outside the protected area.

To tag the shark, one must first capture it, put it on a stretcher where it is secured and taken onto the research vessel.  Once there, it is measured and satellite tags are fixed to the dorsal fin. During this process, seawater is supplied to the shark through a hose that runs it over their gills.

Tags have so far been placed in 5 silky sharks, 2 hammerhead sharks, 2 Galapagos sharks, and 2 black tip sharks.   The tags include a small antenna - so when the shark's dorsal fin pokes out of the water (as it does when they are swimming at the surface), the device sends a satellite signal which is then relayed back to the Park's monitoring.  Earlier such studies have demonstrated that some sharks move between Cocos Island (Costa Rica) and Galapagos.

CNH Tours notes that this kind of information helps develop effective shark conservation policies.  For example, if the scientists discover that the sharks migrate regularly to other places, it will be clear that their long term conservation will require cooperation with the fisheries management authorities in these places as well.

The large schools of hammerhead sharks are one of diving wonders of Galapagos - divers come from around the world to witness this phenomenon.   But sharks have been aggressively fished over the past several years, mostly to feed the growing Chinese market for "shark fin soup".    Even in the Galapagos marine reserves, sharks are often illegally fished for their fins and all efforts must be made to stop this practice, both by controlling illegal fishing, and by encouraging the main consumers of shark fins that the practice is not sustainable.