As evidenced by the previous accidents, a considerable increase in the marine vessels over the past decade is an indication of the high oil spill risk potential for the Istanbul Strait (Bosphorus) that bears a natural beauty and various human-use resources. This situation poses a considerable threat on the Bosphorus ecosystem which is one of the most important migration routes of the Mediterranean and Black Sea fish and of many continental bird species. Therefore, this study aims to map the ecosystem resources regarding possible oil spill threats. With the help of Environmental Sensitivity Index (ESI) classification, fish and bird species encountered around the Bosphorus were collected through a literature and field survey conducted during 2005-2013. Ecosystem dataset contains name of the species, their abundance, time and location of presence. It is further compiled into a geo-database where data on marine accidents were analyzed and risk posing areas regarding to marine accidents and possible oil spill locations are determined. With the analysis of the most probable accident locations through the Bosphorus, information is produced on a monthly basis on the potential risk that might affect the fish and bird species by exposure to oil spills. This study shows the importance of an ecosystem geo-database and its utility regarding oil spill risk.