What are fish ladders?

Fish ladders are manmade structures that are used to pass fish above blockages, usually dams.

While all fish need to have free movement up and down streams, it is critical to the life cycle of some species. Anadromous is a term used to describe fish which live in saltwater (ocean) but must migrate into freshwater streams to spawn.  When blockages, such as dams, prevent these fish from accessing critical spawning habitat, biologists can create fish “ladders” that allow the fish to swim around the blockage. 

The Bay States -- Maryland, Pennsylvania and Virginia -- have been working to remove dams and construct fish ladders to reopen habitat to fish; since 1987 more than 1,000 miles of waterways have been reopened.   

- Jim Thompson
DNR Fish Passage Coordinator

Photograph by Martin Gary
(click on photo for larger view)

 For more information:
History and Background of the Fish Passage Program

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