Distribution, community composition and vulnerability of fish species in the Algeti River Basin (Georgia)

This study presents the first comprehensive survey of fish species’ diversity and distribution in the Algeti River and its reservoir in Georgia, a region within the Caucasus biodiversity hotspot. The research, conducted between 2016 and 2022, identified 19 fish species, including nine native to the Kura River basin and ten introduced or invasive species. The construction of a hydro power plant (HPP) dam in the 1980s and other subsequent anthropogenic activities have significantly altered the river ecosystem, creating distinct upstream, reservoir, and downstream sections with varying fish communities. The study reveals a concerning ongoing impact of anthropogenic factors on the Algeti River's fish fauna and whole ecosystem. The dam impedes fish migration; in addition, pollution, particularly in the mid-downstream section, has led to habitat degradation and a decline in native species. The introduction of non-native species, including predatory and bioturbator species, poses a substantial threat to the native fish populations. Our findings highlight the urgent need for conservation action to mitigate these threats. While the river's headwaters are within a protected area and some species are on the Red List of Georgia, alone these designations are insufficient safeguard. Effective conservation strategies must include stricter enforcement against illegal activities like poaching, as well as better pollution control and habitat management to preserve the Algeti River's biodiversity. This baseline study provides critical data for future research and conservation planning in this ecologically important region.