HABSCORE - applications and future developments of related habitat models

1. The role of habitat evaluation methods (HEM) is briefly reviewed in the context of contemporary fisheries management. Management requirements of HEMs for fisheries purposes include setting spawning targets, and assessing compliance against these targets, environmental impact assessment, habitat protection and restoration, survey design, classification and reporting of fish and habitat resources. Currently available or emerging HEMs are compared against these management applications. 2. HABSCORE is a system of salmonid stream habitat measurement and evaluation based on empirical models of fish density against combinations of site and catchment features. An outline is provided of the derivation, performance and applications of HABSCORE. 3. The effectiveness of HABSCORE and other HEMs depends on their ability to explain the spatial component of variance seen in fish population data. Variance analysis of HABSCORE performance shows how the relative importance of spatial and temporal variance alters at different geographical scales, the latter (indicative of synchronous variation) being much more important within small tributaries. HEMs based only on catchment features explain significant proportions of spatial variance, demonstrating their potential in catchment-scale evaluation. 4. Other contemporary HEMs considered include PHABSIM, procedures to transport spawning targets between rivers, fisheries classification, and habitat evaluation for restoration purposes. All of these have limitations in the management of habitat at catchment scale. Future fisheries applications, such as setting spawning targets or integrated catchment management planning, will probably require some combination of GIS-based, extensive classification and site-based field observations of habitat quality. This approach is being developed through the Fisheries River Habitat Inventory which links HABSCORE to a national fisheries classification system. (C) 1998 John Wiley & Sons, Ltd.