Botelho, P.F.A study on the ichthyofauna from the Ria Formosa Lagoon

The ichthyofauna of the lagunar system of Ria Formosa (South Portugal) has been monthly sampled using the beach seine between November 2000 and October 2001 in six different sites. 16184 individuals belonging to 63 species of fishes distributed by 25 families were collected. Many species have a protected status and/or commercial value. The most represented families were Sparidae, Gobiidae, Labridae e Syngnathidae. Shanonn diversity wasn´t very high because the dominance of Atherina spp.. Resident, migratory and occasional species occur and showed, respectively, a more relevant contribution in terms of abundance, biomass and specific richness. The more rich and diverse communities occur in the vegetal substratum sites, while deeper areas are characterized by reduced captures in terms of individuals and species. In the inner sites of the lagoon the pelagic fishes assume a considerable importance. The seasonal variation was well marked and strongly influenced by the migratory community. Spring and Summer are the seasons in witch several juvenile coastal species migrate into the lagoon. Some of these, like Sparidae and Moronidae, have a high commercial value. Winter, on the other hand, shows a community with few individuals and low diversity, essentially, composed by resident species, since most of the species that colonized the lagoon during Spring return to the sea before having completed the first year of live. Ria Formosa, being characterized by a high specific richness, shows the ideal conditions for the development of several coastal species, most of them with high commercial value.