The goal of this work was to study the influence of dynamite used for blast fishing from July 2006 to July 2007 on marine applications and determine the physico-chemical parameters of seawater before and after blasting off the coast of Hekim Island located in Izmir Bay, Turkey. Field applications consisted of four steps; these were blast operations, sampling of water quality and substratum and laboratory analysis. Dynamite, which was made from artificial fertilizer, sulfur and diesel, was blown up using a fuse and detonator at 2 to 3 meters' depth in three different substratum (sea grass, sandy and rocky). According to the results of CTD measurements, temperature and salinity values did not change significantly. Before blasting, dissolved oxygen level was measured as 12.63 mg.L-1 at pH 8.29, while dissolved oxygen was measured as 13.32 mg.L-1 at pH 8.32 after the blasting. Results obtained from the present study showed that the blasts l fatally affected many fish species in a large-scale area and this effect occurred due to fish's skeletons being damaged by the high pressure. However, changes in physicochemical parameter levels were found to be too low to cause damage to the fish.