Convict tang surgeon fishes mating and grey reef shark having frenzy

convict tang spawning reproduction surgeon fish sperm releasing eggs mating shark frenzy grey eat pass undersea Fakarava Tetamanu ocean current school tropical Polynesia banc poisson chirurgien bagnard fraie sperme gamète laitance requins gris frénésie manger passe courant ocean Pacifique sous marin Polynésie group nager convict surgeon fish