A fish ladder, also known as a fishway, fish pass or fish steps, is a structure on or around artificial barriers (such as dams and locks) to facilitate diadromous fishes' natural migration. Most fishways enable fish to pass around the barriers by swimming and leaping up a series of relatively low steps (hence the term ladder) into the waters on the other side. The velocity of water falling over the steps has to be great enough to attract the fish to the ladder, but it cannot be so great that it washes fish back downstream or exhausts them to the point of inability to continue their journey upriver.
Famous quotes containing the words fish and/or ladder:
“Thou stately stream that with the swelling tide
‘Gainst London walls incessantly dost beat,
Thou Thames, I say, where barge and boat doth ride,
And snow-white swans do fish for needful meat:”
—George Turberville (1821–1873)
“O, when degree is shaked,
Which is the ladder of all high designs,
The enterprise is sick. How could communities,
Degrees in schools, and brotherhoods in cities,
Peaceful commerce from dividable shores,
The primogeniture and due of birth,
Prerogative of age, crowns, scepters, laurels,
But by degree stand in authentic place?
Take but degree away, untune that string,
And hark what discord follows. Each thing meets
In mere oppugnancy.”
—William Shakespeare (1564–1616)