Monitoring Fish Populations in River SACs

Abstract

The EU Habitats Directive (92/43/EEC) on Conservation of Natural Habitats and of Wild Fauna and Flora stipulates that Member states maintain or restore habitats and species in a condition that ensures their favourable conservation status in the community. To comply with this Directive requires assessment of the conservation status of aquatic species in rivers designated as Special Areas of Conservations (SACs) against a predetermined set of objectives. This paper describes the protocols developed to determine the condition status of lampreys, bullheads, shad and Atlantic salmon in SAC rivers in the UK.

Two strategies are proposed for assessment of favourable conservation status of fish species of in SAC rivers. The first approach classifies the extant density of fish of various life stages against pre-set targets and the second examines the demographic structure of the population, i.e. the contribution of juveniles to the population, to demonstrate recruitment success. To achieve favourable conservation status, where abundant, the fish population should consist of a pre-determined proportion of young of the year or juvenile age classes. Further assessment of the status can be derived from mapping the distribution of the target species in individual SAC rivers. Favourable conservation status should be recorded if there is no decline in distribution from the current, or where available, historical pattern. Reasons for not achieving favourable condition status should be determined from environmental and physiochemical data collected in conjunction with the fisheries surveys.