SPAWNING BEHAVIOR OF THE MEDITERRANEAN DUSKY GROUPER EPINEPHELUS-MARGINATUS (LOWE, 1834) (PISCEA, SERRANIDAE) IN THE MEDES-ISLANDS-MARINE-RESERVE (NW MEDITERRANEAN, SPAIN)

Spawning of the Mediterranean dusky grouper Epinephelus marginatus (Lo we, 1834) was observed for the first time in summer 1996 during scuba diving surveys in the Medes Islands Marine Reserve (NW Mediterranean). Ten spawning events were observed, which occurred at sunset, in the e venings around the new moon of August. A mature female (usually betwee n 50 and 75 cm TL), in the standard mottled colour pattern, and a larg er (more than 100 cm long) dominant male, in a conspicuous silver stre aked colour-pattern, ascended up to 12 m side by side, spiralling in a n anti-clockwise direction two or three times, from the bottom to shal low warmer waters, where the ova and sperm are released. Some traits o f variability over this common pattern of spawning are described. Pred ation by saddled bream Oblada melanura, which concentrate in great num bers after each spawning suggests a very low survival of the spawned e ggs.