by project student @vitalheim
What a week! Even though this years’ hammerhead season is slowly coming to an end, the last 7 days have been a tremendous success for our research and our team.
We’ll skip the usual weekly statistic for once because we are very excited that our team efforts allowed us to tag two of our female great hammerhead sharks.
The reduced dive activity gave us the opportunity to go out in the field with the intention to tag our great hammerhead sharks. On Friday morning, we captured and tagged Medusa (Shark-ID #16)
and Scylla (Shark-ID #24).
Medusa was tagged with an internal 10-year acoustic tag, and we were able to tag Scylla with an internal 10-year acoustic tag and an external satellite tag.
The so-called Pop-Up Satellite-Linked Archival Tag (PSAT) that was used to tag Scylla will archive and highlight her movement patterns, habitat preferences and potential migratory corridors. The PSAT actively corrodes the pin to which the tether is attached after 8-months, thus releasing the PSAT from the shark. The tag then floats to the surface and transmits summarised information via the Argos Satellite System. The transmitted messages also provide us with the position of the tag and the time of release what allows us to retrieve the tag.
The PSAT was deployed applying the bridle method. Using a bridle to attach the satellite tag to the first dorsal fin of an individual allows the tag to be free moving behind the trailing edge of the fin. Compared to other deployment methods, the bridle has been shown to have a high success rate regarding the duration the tag stays on an individual. It was this method allowing us to track the movements of Nemesis (Shark-ID #17)
for 9 months in 2016. The results obtained from that tag revealed her long-distance migrations (>1600 km). Are you interested to learn what other methods are used to advance our understanding about the movement ecology of our great hammerhead sharks? We are looking forward to telling you everything about the deployed acoustic tags when it is time for another Hammerhead-Sunday in exactly one week! 📸 @paddy__burke
#bimini #sharklab #bahamas #shark #science