Fisheries impact assessments

A variety of developments, including water abstraction for hydropower generation, can affect fisheries in a number of ways. These include fish passage, attraction flow, and reduced water in the derogated reach.

A typical assessment would evaluate the sensitivity of the site in terms of species present, spawning and juvenile habitat and the potential impact on upstream migration. Appropriate mitigation may take the form of improved fish passage and a minimum residual flow. Sites vary significantly in terms of sensitivity and it is not possible to apply a generic abstraction regime to all sites. For more sensitive sites, a fisheries assessment is essential to achieve the right balance and hence efficient use of the resource, while ensuring ecological integrity and fisheries are not impacted.

A PHABSIM study is a useful tool for assessing the impact of abstraction on the derogated stretch of river. A full study is usually only considered for very large schemes where there is a significant potential impact. A CUT DOWN PHABSIM (see reports) is cost effective and relevant for smaller schemes.

Other components of a fisheries study include:

• Spawning and juvenile habitat
• Fish surveys, including electro fishing
• Macro invertebrate studies
• Assessment of fish migration/fish passage issues

Examples of reports

	River Dove Hydro Electric Scheme PHABSIM Analysis and Report Date: August 2008 Download PDF here
	Castleford Mill Hydro Power Proposal River Aire -Fisheries Assessment Date: October 2009 Download PDF here