Knowra Fish passage Fish passage Fish passage comprises structures and operating systems that let fish move past barriers such as dams, weirs, and culverts. Designs may support upstream movement, downstream movement, or both.
Fish ladder : A stepped channel or series of pools that lets fish ascend around a barrier. Pool-and-weir and similar ladders provide a gradual upstream route around dams and weirs.
Fish migration : The regular movement of fish between habitats, often for feeding, growth, or reproduction. Passage structures preserve migration routes interrupted by dams and other barriers.
Fishway hydraulics : The study of water depths, velocities, turbulence, and flow patterns in fish passage structures. Hydraulics determine whether fish can find and traverse a route.
Fish passage efficiency : The proportion of fish attempting passage that successfully complete it within a defined period. Efficiency measures whether a structure actually enables movement, rather than merely existing.
Selective fish passage : Passage design or operation that enables target species to move while limiting others. Managers may need to reconnect native fish while restricting invasive species.
Fish lift : A mechanical system that collects fish and carries them over a barrier in a tank or container. Lifts transport fish where a ladder would be impractical, especially at tall dams.
Dam removal : The deliberate dismantling of a dam to restore a river and its ecological processes. Removing a barrier can restore movement without relying on a passage structure.
Swimming performance : The capacity of fish to swim at different speeds and sustain movement over time. Passage routes must match the swimming abilities of target species and life stages.
Fishway attraction efficiency : The proportion of migrating fish that locate and enter a fishway. Fish may fail to benefit from a passable route if its entrance is hard to find.
Downstream fish passage : The movement of fish downstream past barriers, through routes such as bypasses, spillways, or turbines. Downstream routes often involve distinct risks and design challenges from upstream passage.
Show all 27