Does the use of in-stream structures and woody debris increase the abundance of salmonids

Abstract

In-stream structures (such as flow deflectors, weirs and woody debris) have been in widespread use for the last eighty years to increase the production of fish stocks, primarily salmonids, but also species of conservation concern such as European Bullhead Cottus gobio. 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 hard to develop a consensus regarding the utility of in-stream structures despite their continued use. This systematic review formally synthesises empirical evidence regarding the effectiveness of in-stream structures in terms of impact on abundance of salmonid fish and C. gobio using a documented a priori protocol