The quantity and species compositions of both retained and discarded bycatch of the Kuwait’s shrimp fishery was investigated for the first time directly through onboard observation and sampling of a fishing vessel. The observations were conducted on a 131 tonne double-rigged shrimp trawler twice a month during the shrimp season from September 2010 through January 2011. The shrimp catch rate declined sharply from 19.6 to 1.1 kg/h as the season progressing, while bycatch rate remained in a high and relatively stable between 106 and 81.5 kg/h, and resulted in a large variation (5.4-73.6) of byatch-to-shrimp ratio from the season’s start to the season end. The retained bycatch was always low (11.6-15.9% of the total bycatch) throughout the season. The total species recorded in the bycatch was 112, with 55 retained and 93 discarded at sea. Thirty-nine species occurred both in retained and discarded bycatches. Saurida tumbil , Nematalosa nasus , Sphyraena flavicauda , Acanthopagrus latus and Otolithes ruber were the most dominant fish species in the retained bycatch. Discards dominated both by undersized commercially valuable species including Ilisha melastoma , Pomadasys stridens , Nematalosa nasus , Saurida tumbil and Upeneus doriae , and by non-commercial species such as catfishes, sharks and rays. Based on monthly bycatch-to-shrimp ratio, the percentage of the retained bycatch and the recorded shrimp landings, the total bycatch of Kuwait’s shrimp fishery was estimated to be 15,704 t for the 2010/11 season. Of the total bycatch, only 2192 t (14%) was retained, while the majority 13, 512 t (86%) was discarded at sea. Of the 93 discarded species, 55 are commercially valuable species, representing 61% (8242 t) of the total discarded bycatch.