A Short-term Study of the Effects of a Habitat Improvement Programme on the Distribution and Abundance of Fish Stocks in a Small Lowland River in Shropshire

Abstract

Following the implementation of an experimental habitat improvement programme in the River Perry, a small lowland river in Shropshire, using low dams, current deflectors and artificial cover structures, marked changes in fish distribution and abundance were recorded in some study sections which appeared to be related to the effects of the improvement structures in recreating natural river features such as the pool-riffle pattern. Over the site as a whole, the population densities of dace and chub increased from means of 325 fish ha−1 and 229 fish ha−1 in the year before habitat improvement to means of 568 fish ha−1 and 313 fish ha−1 in the year following habitat improvement, increases of 75 and 37% respectively. Similarly, standing crops of dace and chub increased from pre-improvement means of 19.7 kg ha−1 and 66.6 kg ha−5 to post-improvement means of 25.8 kg ha−1 and 83.0 kg ha−1, increases of 31 and 25% respectively. Distribution mapping studies revealed considerable fish relocation following habitat improvement, with large concentrations of fish being recorded in the vicinity of the improvement structures. It is concluded that the improvement programme was successful in partially mitigating the adverse effects on the fishery of previous land drainage river channel works.