The second Mokarran Protection Society campaign took place in Rangiroa, an atoll in French Polynesia, from December 2020 to February 2021. This year, the research areas and techniques carried out to understand the seasonal presence of the great hammerhead shark, Sphyrna mokarran, in the Tuamotu Archipelago, are now wider. After having explored the Tiputa pass, the exchange interface between lagoon and open ocean, this year's focus was the lagoon itself. This vast inland sea remained a mystery since very few sightings of great hammerhead sharks have been reported so far. Yet, observations made in the pass prove that individuals enter the lagoon and return to the ocean frequently.
© Banner photo: Thomas Pavy/Mokarran Protection Society
This mission's first results were already promising. With more than 180 observations and 70 laser measurements for the two atolls combined, 23 different individuals have been identified on Rangiroa and 7 on Tikehau. Connectivity has not been established between the two atolls, but the data is still being analysed. One individual, recognisable by its curved dorsal fin, was observed in the area last year, thereby making him the first inter annual seasonal resident. The other individuals identified this season had not been observed previously, which means that Rangiroa's population of great hammerhead shark reaches at least 50 different specimens in two years of scientific campaign and probably many more. Again in 2021, 100% of the gendered individuals were identified as females with total lengths ranging from 2,14 m to 4,5 m, a measurement record for the association.
© Photo: Thomas Pavy/Mokarran Protection Society