Diversity, abundance and seasonal variation of the ichthyofauna associated with shrimp farming in a tropical estuary in northeastern Brazil

The precarious nature of the existing data on marine fish diversity on a global scale is accentuated in tropical areas, where taxonomic inventories of fish species are particularly incomplete. In the present study, we investigated the diversity, abundance and seasonal variation of the ichthyofauna associated with shrimp (Litopenaeus vannamei Boone, 1931) farming in a tropical estuary in northeastern Brazil. The experimental data were obtained at an aquaculture farm located on margins of the Guarairas lagoon (06A degrees 12'S, 35A degrees 09'W) in the state of Rio Grande do Norte. We sampled four shrimp culture cycles carried out from April to November 2005 during the rainy and dry seasons. Fishes were harvested at the termination of each culture cycle. We collected 36,681 fishes, comprising 26 families and 54 species. Shrimp culture cycles conducted in the dry season presented a more diverse fish community, albeit less abundant, than culture cycles carried out in the wet period. The most abundant families were Engraulidae in the wet season and Scianidae in the dry period. Juveniles of the engraulid Lycengraulis grossidens (Agassiz, 1989), a marine migrant, represented 87.67 % of total abundance in the wet season and 35.26 % of all individuals in the dry period. In conclusion, this study provides evidence of an abundant and diverse ichthyofauna associated with shrimp farming in northeastern Brazil. It also points to the necessity of finding alternatives to mitigate the entrainment of larval and juvenile fishes in shrimp ponds.