Condition of Barbus sclateri from semi-arid aquatic systems: effects of habitat quality disturbances

This study investigated the relationships between fish condition and environmental variables in Barbus sclateri from semi-arid freshwater ecosystems in the south-eastern Iberian Peninsula. Two main habitats were studied: semi-arid streams characterized by strong seasonal fluctuations in flow level (droughts and floods) and reservoirs (artificial ecosystems characterised by waters of high conductivity). The mass–length relationships were used to test differences in fish condition between nine stream populations and five reservoir populations of B. sclateri from the Segura River basin. The relationships between seven ecosystem variables (conductivity, oxygen concentration, water temperature, pH, seasonal water flow, submerged vegetation and sub-basin location) and fish condition were analysed. The ecological variables that accounted for most of the variation in fish condition were seasonal water fluctuation and water conductivity. The condition of B. sclateri populations may be a good indicator of fish habitat quality in Mediterranean semi-arid freshwater ecosystems and should be considered when such populations are subjected to sports fishing regulations, recovery plans or any other management programme. # 2003 The Fisheries Society of the British Isles