Slide 54 of 75
Notes:
The creation of fish barriers is another impact of urban development. Barriers can prevent the movement of both anadramous and resident fish. In some cases, the fish barriers are created by culverts that are put in stream crossings for roads and other urban infrastructure. As the stream erodes down, vertical barriers to fish movement are created that cut off spawning areas. Menhaden, herring, striped bass, or salmonoids that are trying to move up to fresh waters to spawn in spring will likely encounter fish barriers that they cannot surmount. In many areas of the East Coast as well as the West Coast where salmon spawn, fish barriers are a major biological problem associated with urban development.
Culverts like these act as barriers to fish migration.