Impacts of Trawling on Distribution and Diversity of Gastropods in the Persian Gulf: the Bahrakan Fishing Area

This study was undertaken to survey impacts of bottom trawling on distribution and diversity of gastropods of the Bahrakan Fishing Area (BFA), of the northwestern coasts of the Persian Gulf. Gastropod samples were collected from depths of 6m and 10m at 18 randomly selected stations in three occasions, right before the opening of shrimp trawling seasonand two weeks and 3 months after the fishing season ended. Majority of sediments displayed silt-clay texture. Abundance, diversity, richness and evenness indices of gastropods decreased but conversely, Simpson dominant index increased in all post–season samplings compared to pre-season samplings in both depths (P<0.05). Biomass of gastropods declinedafter trawling and no recovery occurred after three months.However, the abundance of smaller gastropods increased after trawling. In both depths, Acteocina involuta was found abundantly in two weeks after trawling.Impacts of trawling were higher in shallow areas (6m depth) than that in the deeper areas (10m depth).