The purpose of this study is to determine the amount of bycatch and discards of fish caught by bottom trawlers operating along the Black Sea coasts of Turkey and discards changes depending on the depth. The study was conducted during the September 2009-April 2010 fishing season. Twenty-one bottom trawler operations were sampled and the catch composition was determined. A total of 26 species were caught, which included 22 species of fish, 2 species of arthropods, 1 gastropod and 1 bivalve. Two of these were target species (Mullus barbatus, Merlangius merlangus), while 25 species were discarded, including trash fish and specimens below the legal size. A total of 2142.76 kg of biomass was caught during the operations, of which 53.99% was bycatch. The weighed discard rate was determined as 42.06% and two different groups were identified in discards (T1: 10-57 m, T2: 72-118 m) based on the depth. Significant differences were identified between these depth groups (p<0.05). It was determined that the biomass (kg h(-1)), the evenness index (J) (p<0.05), the average species number and species richness (D) (p<0.01) of the discards showed significant differences, but that the difference between species diversity (H) was negligible. No difference was found (p>0.05) between the ecological parameters of landings.