The research team based out of the Galapagos Islands have just returned from their cruise to Darwin and Wolf.
A Galapagos shark is brought alongside the boat for tagging. Once the tag is attached, the hook is removed and the shark swims away undisturbed.
The main objectives of this cruise were to carry out range tests for the tag-detecting receivers at some of the key sites, and to evaluate whether the new mooring system would work.
The sea conditions were quite rough at first, due to the aftermath of the earthquake in Chile, but what most surprised us was the water temperature – almost 30° Celsius at the surface and not much lower below the thermocline.
Possibly as a result of this warm water, combined with the time of year (there appears to be a seasonal low abundance of hammerheads between March and May), we did not place satellite tags on hammerheads – this activity was postponed until the following cruise. However, the range tests, visual censuses and data downloads were all carried out successfully.
Once back in the central islands, we were invited by the Offield Foundation team, who were in Galapagos studying the movements of marlins, to tag sharks around Santa Cruz onboard the Kelsie Lee.
Thanks to the support from Packy Offield and his colleagues, we placed 5 ultrasonic tags on Galapagos sharks, bringing our tally of tagged Galapagos sharks up to 20. These will form the basis of a study to look at the movements of these sharks between islands in the central archipelago and the northern islands of Darwin and Wolf.
The Offield Foundation also donated a significant number of satellite tags to the Galapagos National Park Service. These will be placed on hammerheads over the coming 3 years, so that we can understand the migratory pathways of these sharks, with a special focus on where the females go to give birth.
