The annual blue water spawning events of Moorish Idols (MI) and Orange spine Surgeonfish (OSS) in Palau, along with the high-stakes predator-prey interactions between these fish and grey reef sharks, was highlighted in the BBC series Asia, airing on November 3, 2024.
The fascinating research behind these spawning events was detailed in a paper by local marine experts Mandy T. Etpison and Dr.Patrick L. Colin. The study focuses on the aggregation of these fish species during the spawning season, which takes place from December through March, with peaks in January and February. These fish leave the safety of the reef to release their eggs into open water, making them vulnerable to predators like grey reef sharks. The study documents how large numbers of sharks follow the ascending fish, resulting in high predation rates during this critical reproductive phase.
