This study presents estimates of numbers and biomass of discarded and landed catches from the commercial prawn trammel net fishery in Izmir Bay. A total of 43 finfish and 29 invertebrate species were identified in catches sampled between May and October 2003, with 26 species landed by fishers and 46 species discarded. Melicertus kerathurus, Mullus barbatus and Solea solea dominated the landed catches. Average ratio of landed to discarded fish by number and weight was estimated as 1 : 2.32 and 1 : 0.77, respectively, demonstrating relatively low by-catch ratios compared to other shrimp by-catch studies. This study shows that trammel nets have a much lower discard ratio than the shrimp trawls in other parts of the world. The benefits of shifting toward passive trammel nets in coastal areas are discussed.