Profiles and Biology of Western European Streams as Related to Fish Management

Abstract In the running waters of temperate Western Europe there are four main biological zones, each of which is characterized by a distinctive fish fauna. These are designated; (1) trout, (2) grayling, (3) barbel, and (4) bream zones. They are related basically to longitudinal section (slope of the stream bed) and to the cross section of the stream and its valley. The physical and biological characteristics of these zones are discussed together with the concepts “slope-rule” and “slope-graph”, which express these relationships, and which have proven useful for evaluating and comparing running waters and for estimating fisheries potentials of streams from topographic information.