Fish Blockages

Two men stand on a hillside overlooking a small, rocky stream, which flows uninterrupted through a series of two culverts. — Mike Lovegreen, right, and Mike Jura of the Tioga County Soil and Water Conservation District visit a culvert replacement on a tributary of West Branch Owego Creek at Luszczek Family Farm in Speedsville, New York. (Will Parson/Chesapeake Bay Program)

FAQ

What is fish passage?

Fish passage is the ability of fish to migrate up rivers, streams and other waterways, often to access spawning or rearing ground. Barriers to fish passage (which include road culverts, dams, dikes and other obstructions) can reduce the distribution and habitat available to American shad and other migratory fish and, in some cases, eliminate fish populations altogether.

How do fish passageways work?

Fish passageways allow American shad and other migratory fish to pass over dams and reach their upstream spawning grounds. There are five major fish passageway designs used in the Chesapeake Bay watershed: denil, steeppass, vertical slot, pool and weir, and fish lifts.

How do dams affect rivers and streams?

Dams can block American shad and other migratory fish from reaching their upstream spawning grounds. Dams can also affect the natural flow of rivers and streams.

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Terms

Fish passage

Features of a dam that enable fish to move around, through or over a dam without harm. Generally an upstream fish ladder or a downstream bypass system.

Anadromous fish

Fish that spend their adult lives in salt water but must migrate to freshwater tributaries to spawn. For example, Atlantic sturgeon and American shad are both anadromous fish.

Fish ladder

A series of ascending pools of running water constructed to allow fish to swim upstream around or over a dam.

Catadromous fish

Fish that spend most of their lives in freshwater tributaries but must migrate to salt water to spawn. The American eel is the only catadromous fish in the Chesapeake Bay region.

Migration

The seasonal movement of animals from one region to another.

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