Barrage de Verbois on the Rhône River, Switzerland and Nishiotaki
Dam, Japan from Wikimedia Commons:
http://commons.wikimedia.org/wiki/File:Echelle-poisson-verbois.JPG and
http://commons.wikimedia.org/wiki/File:Nishiotaki_Dam_fish_ladder.jpg
Dictionary of Ichthyology
ladder = a series of steps with flowing water and pools enabling a fish to circumvent an obstruction such as a dam by leaping from step to step. Also called fishway, fish pass.
