Pacific Gas and Electric fish trap on the Metolius River in central Oregon, USA. The purpose of the trap is to capture juvenile Chinook Salmon (Oncorhynchus tshawytscha) and Kokanee (Oncorhynchus nerka) migrating downstream and thus obtain an estimate of the number of fish produced in the upper river and its tributaries. The trap is checked daily and fish are counted, measured, tagged and released unharmed. May 2008