Shark Project Update

31 May 2024

Conservation

Summary of activities and preliminary findings

From March to May 2024, Conservation team was pleased to host project partners from the Darwin-funded Human-Shark Conflict Project, a collaborative initiative with the University of Exeter, the Zoological Society of London, and the University of Windsor. During their visit, the team serviced, collected data from, and redeployed a range of acoustic and oceanographic instruments.

In addition to their fieldwork, the team engaged the community with a presentation detailing the project’s progress and sharing preliminary findings. The field activities conducted from March to May also included the acoustic tagging of additional sharks to expand monitoring efforts.

Acoustic receivers, ADCPs (measuring water current direction and speed), and temperature loggers were recovered, serviced, and redeployed following the collection of data from these instruments. Data downloaded from the receiver’s indicated movements of the 34 acoustically tagged sharks from 2023 to 2024, including both Silky and Galapagos sharks. Preliminary findings show that approximately 85% of Galapagos sharks demonstrated very high local residency to the island, while the intermittent residency of Silky sharks showed movements away from the island for several months, with occasional returns. Hotspots of general shark activity were identified around the island (Figure 1). The thermocline and water temperatures for the year were recorded (Figure 2) with some evidence showing that shark movement was associated with shifts in water temperature. Blood and fin clip samples are currently being processed in the lab at the University of Exeter, with early isotope analysis indicating a similar diet between the Galapagos and Silky sharks.

Figure 1 Hotspots of shark activity identified around the island

Figure 2 Example of water temperature captured from one data logger

Future plans for the acoustic array include continued data collection for another 12 months, with the data to be recovered and analyzed as part of a larger PhD project in March 2025. Further analysis will help to continue understanding the oceanographic influence and fine-scale movements of the sharks around Ascension.

For more information, please contact Daniel Simpson at daniel.simpson@ascension.gov.ac or visit us at the Marine Festival.