Fish assemblages of Cais do Carvão Bay (Madeira Island) determined by the visual census technique

Fish assemblages in Cais do Carvão Bay, Madeira Island, a proposed marine protected area (MPA), were determined from a diver visual census. A total of 32 transect counts were performed. Habitats sampled included sandy bottom, rocky boulders, vertical walls and rocky outcrops. Species richness, diversity, density, trophic structure, size and spatial organization were documented for the fish assemblages. Forty‐four species from 23 families were encountered; 32% belonged to Sparidae (10) and Labridae (four). The greatest species richness (25) was observed in rocky boulder habitat at 10–15 m depth, while the lowest (five) occurred over a deeper sand habitat. The greatest density (760·5 individuals per 100 m²) was recorded over rocky outcropping (20–25 m deep), and the lowest of 11·6 individuals per 100 m² was over a sand bottom at 10–15 m depth. Thalassoma pavo , Abudefduf luridus and Chromis limbata had higher densities on hard bottoms, while Heteroconger longissimus was the most abundant species in sand bottom habitats. No significant differences were detected for all indices calculated among depth intervals for sand and rocky boulder stations. Sand and rock boulder substratum, however, differed significantly for the 10–15 m depth stratum.