SPATIOTEMPORAL VARIATIONS IN THE DISTRIBUTION AND ABUNDANCE OF FISH IN THE YORKSHIRE OUSE SYSTEM

An account of the dynamic nature of fish abundance, distribution and s tock composition in the Yorkshire Ouse system is presented. In determi ning in situ energy and nutrient fluxes, knowledge of the magnitude an d distribution of fish biomass is important, but the mobility of fishe s causes uncertainty in attempts to model the influence of fish biomas s on carbon and nutrient fluxes. Data are presented which demonstrate how, within the Ouse system, fish abundance and species composition va ry on spatial scales related to physical and biotic environmental para meters, that local abundance mai change over short and long time scale s and that these changes may be caused by ecosystem perturbations or b y response to environmental cues. Opportunities for measuring the infl uence of spatio-temporal variations on nutrient and energy flux within the Ouse system are discussed. (C) 1998 Elsevier Science B.V.