Fish-based indices in catalan rivers: Intercalibration and comparison of approaches

Abstract

Freshwater ecosystems are among the most affected by anthropogenic disturbances, and fish have several advantages for monitoring them, such as the response at larger temporal and spatial scales and its visibility to the society. This chapter summarizes our experience in developing fish-based indices in Catalonia. We describe some differences observed among crews in electrofishing captures and habitat assessments. We also analyzed the suitability of a single pass for conventional monitoring in the region and differences in capturability among sites and species by comparison with multiple passes and block nets. Furthermore, we summarize the results of two contrasting approaches, a site- and a type-specific one (IBICAT2a and IBICAT 2b) applied to Catalan rivers. The site-specific was not successful and further data are needed for its improvement. A protocol for the computation of a type-specific, multimetric index (IBICAT2b) is given. The IBICAT2b fish index uses 4–8 metrics depending on river type and has been validated with environmental pressures both throughout Catalonia and the whole Ebro River basin. An Excel file is also given as an online supplementary material for the computation of this fish index.