Seasonal migration and habitat shifts of the cyprinid fish Schizothorax eurycephalus in a Central Asian mountain river

Abstract Freshwater biodiversity in Central Asia faces increasing pressure from anthropogenic impacts. A group of fish species of ecological and economical importance in the area are snow trout, cyprinids of the genus Schizothorax . However, fundamental knowledge to aid species conservation is limited, such as information about their seasonal movement patterns and habitat preferences. Consequently, in this study we tracked 27 snow trout ( Schizothorax eurycephalus ) equipped with radio transmitters for almost two years in the transboundary Shakhimardan River basin in the Alay mountain range, Uzbekistan and Kyrgyzstan. Movement distances and directions were analyzed using descriptive statistics and linear mixed models, and habitat use were assessed using ordinal logistic regression. Our results show that snow trout had a movement range up to 18 km and exhibited a seasonal migration pattern, moving downstream in spring and upstream in autumn. We observed that many fish migrated upstream into the groundwater-dominated Koksu River for wintering, potentially highlighting the role of thermal refugia. They mostly used habitats in medium-to-fast flowing sections with large substrates. This study is the first biotelemetry-based research of fish in Central Asia, revealing details on seasonal migration and habitat use of Schizothorax eurycephalus . Our findings underline the need to preserve aquatic connectivity and structurally diverse habitats in mountain rivers. Incorporating these insights into hydropower development, design and river restoration programs can help maintain ecological integrity while supporting sustainable development.

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