Socio-behavioural context of reproduction in the Mediterranean dusky grouper Epinephelus marginatus (Lowe, 1834) (Pisces, Serranidae) in the Medes Islands Marine Reserve (NW Mediterranean, Spain)

摘要: The evolution of social structures and reproductive behaviours leading to actual spawning in the Mediterranean dusky grouper, Epinephelus marginatus, was studied Medes Islands Marine Reserve on Spanish coast (NW Mediterranean) from February 1995 October 1996. Density, size, sex, colour patterns, relation bottom, swimming activity site occupation were monitored by visual census surveys at monthly daily scales. main observed socio-behavioural trends part comparable with some patterns reported tropical groupers, although differences exist, which might be related temperate conditions northern sea. density groupers area low winter, maximal summer, late June August (up 8-fold increase); numbers rised spring, before beginning activities led mid August, dropped rapidly afterwards. During this long period (about 2 months), dominant males (recognized their highly specific pattern) established territories they displayed aggressively towards neighbouring numerous smaller females (the species is proterogynous); sex-ratio approximately 1:7 (sexually active versus adult females). Territoriality base structuration population; addition, typical pre-spawning include repeated evening gathering open water, appearance colours patterns. This overall pattern changed evenings when (16th - 21st August), patrolling a reduced territory would come mate; behaviour itself described Zabala et al. (1997).The complex structure reproduction Dusky Grouper should considered fishery management, since it could hardly develop under strong human pressure. In respect, contribution protected areas determinant for success NW basin.