DEVELOPMENT OF FISH HABITAT MODELIZATION IN FRENCH STREAMS IN RECENT YEARS

An assessment of quantitative methodologies for fish habitat evaluatio n is presented. By crossing hydraulics, geomorphology and biology, and following the IFIM philosophy (Fort Collins. US Fish and Wildlife Ser vice, Colorado, USA), several results have been obtained : - developme nt and standardization of habitat descriptions at different spatial sc ales (microhabitat, mesohabitat, reach); - evaluation of the habitat t emporal variability using hydraulic simulations; - development of habi tat suitability curves or models from expert advice or from fish densi ty and habitat data collected in streams; - biological tests of the me thodology by comparing predicted versus observed brown trout biomass i n reference streams. This recent advance offers different tools for me asuring the spatio-temporal variability of streams and rivers. This is of high interest for physical impact evaluation, in particular when t he hydrological pattern is altered, i.e. definition of ecological flow s.