Solutions to the Impacts of Roads and Other Barriers on Fish and Fish Habitat

Fabrice Ottburg*, Matt Blank

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapterAcademicpeer-review

5 Citations (Scopus)


As with all wildlife, fish need to move throughout their range in order to complete their life cycles. Unlike other animals, fish cannot leave the stream or river that they are living in or migrating through to bypass a barrier. Structures under roads that facilitate the flow of water, particularly during flood events, are critical to protect the infrastructure and if well designed can provide passage for fish and other aquatic species. However, improper design, construction or maintenance of road-stream crossings can limit or completely prevent fish passage. In addition, roads and traffic can also impact fish and fish habitat by degrading the quality of the streambed, adjacent riparian habitat and water quality, as well as changing patterns in the flow of ground and surface water. 1 Roads and the vehicles that travel on them can negatively affect fish habitat and water quality. 2 Roads and other in-stream structures can be barriers to the movement of fish. 3 Well-informed planning and design of roads can limit the impacts of roads on fish and fish habitat. 4 The most effective road-stream crossings for fish, when long-span 'floodplain' bridges are not an option, are culverts or shorter-span bridges that simulate the natural channel. 5 Specialty culverts and other technical solutions are possible but require careful design and do not provide all the qualities of uninterrupted natural waterways. Roads, railways and other linear infrastructure inevitably intersect waterways, often restricting the movement of fish. New infrastructure should avoid waterways where possible and any crossings that are needed should be designed to allow the natural flow and function of the waterway. Existing road crossings that are barriers to the movement of fish should also be modified to be more natural and improve connectivity for fish. Better designed road-stream crossings also have the added benefit of accommodating flood events and ensuring static infrastructure is stronger and less prone to failure, thereby requiring less maintenance and repair and saving money.

Original languageEnglish
Title of host publicationHandbook of Road Ecology
ISBN (Print)9781118568170, 9781118568187
Publication statusPublished - 2015


  • Barrier
  • Bridges
  • Culverts
  • Fish habitat
  • Fish passage
  • Freshwater fish
  • Migration
  • Stream simulation
  • Water velocity


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