This dataset gathers, total abundance, abundance per size class, total biomass and biomass per size class of two vulnerable fish species, the dusky grouper, Epinephelus marginatus (Lowe, 1834), and the brown meagre, Sciaena umbra Linaeus, 1758, recorded inside and outside the Marine Natural Reserve of Scandola (Corsica, NW Mediterranean) in 2012 and 2018. Fish were recorded by underwater visual censuses performed on belt transects (50 x 15 m) run parallel to the coast between 1 and 40 m depth at 13 sites according to three levels of protection status (integral reserve, buffer zone and unprotected zone). A total of 532 transects were performed in 2012 and 526 in 2018. Corsica 2012-2018-Map Scandola Marine natural Reserve

This dataset gathers total species richness, total abundance and total biomass of fishes recorded in six Mediterranean Marine Protected Areas in summer by underwater visual censuses performed on rocky areas at varying distances from the core of the MPA. Belt transects (25 x 5 m) were run parallel to the coast between 6 and 12 m depth, except in Tabarca Posidonia beds (50 x 5 m). Additionally, reduced fish species richness, abundance and biomass excluding zooplanktivorous fish species (Atherinidae, Clupeidae, Centracanthidae, Engraulidae, Pomacentridae, and the Sparidae Boops boops) were given as their fluctuating abundance and aggregative behavior may mask the effect of protection. Location of the 6 Mediterranean Marine Protected Areas