In French Polynesia, there is a place where every year, thousands of groupers gather in secret followed by hundreds of sharks… The photographer, diver and biologist Laurent Ballesta, with his team, wanted to better understand what motivates these fish to wait until the exact day of the full moon to spawn all at once! With the help of researchers from the CNRS of Moorea, they dived and conducted numerous experiments to study and witness this unique phenomenon. Taking advantage of this period of incredible richness, Laurent Ballesta did a record dive of 24 hours at over 20 meters.

Gombessa Expedition 4 Laurent Ballesta went to observe a gathering of thousands of groupers during the full moon of June 2014 (Le mystère mérou) in the southern pass of the Polynesian atoll of Fakarava, where he discovered a pack of over seven hundred grey sharks. How can this unprecedented density be explained? Could it be that social behaviors govern this wild horde? During three years of preparation, he and the other divers on his international scientific team tamed their fear by abandoning the defensive reflexes that provoke shark aggression, with the aim of slipping into the heart of the raging pack to study and film it from the inside. Sharks fitted with microchips, receiving antennas, hydrophones, an ark of 32 synchronized cameras...: a whole technological arsenal is mobilized for the project. As the groupers approach for their annual spawning, what battle plan will the sharks deploy?

CNRS image的远征南极，法国国家科学研究中心出品。