What is the aim of the review?
To systematically collate and synthesise published and unpublished evidence in order to examine the impact of in-stream structures on the abundance of salmonids and Cottus gobio. The secondary objective was to examine the impact of hydrological and ecological variables on the effectiveness of in-stream structures.

Who's in the review team?

• Gavin Stewart (Lead reviewer) - Centre for Evidence-Based Conservation
• Helen Bayliss
• Dave Showler
• Andrew Pullin
• William Sutherland

At what stage is the review?
This review is now complete.

What is the rationale?
In-stream structures have been widely adopted as a form of river restoration since the early 20th Century, in an attempt to redress habitat degradation and enhance salmonid (and other fish) stocks. However, the type of work carried out and associated monitoring varies widely. A large number of studies, of variable quality, have been undertaken to assess the effectiveness of in-stream structures, often with conflicting results. It has therefore been impossible to develop a consensus regarding the utility of in-stream structures despite their widespread
and continued use.

The Environment Agency identified the need for a systematic review to evaluate
the effectiveness of in-stream devices and the specific question and review protocol were developed through iterative dialogue between CEBC and the Environment Agency.

How were the results obtained?
A number of electronic databases were searched for information using a range of search terms. Internet searches were conducted in order to retrieve any relevant grey literature. In addition, the bibliographies of relevant articles were examined for useful references. The websites of several major UK conservation organisations were also searched for useful publications and subject experts and practitioners were contacted. 33,500 references were identified through the search strategy; 137 of these were accepted into the final review having met all inclusion criteria.

What did the review find?
To read more about this review, its findings, and the implications for conservationists and researchers, please see the Summary or Full Report.

Comments?
If you would like to comment on any aspect of this review, please email us. Your feedback is appreciated.