Ichthyofaunal Diversity, Conservation Status, and Anthropogenic Threat Profiling of Dumboor Lake (Gumti River Basin), Northeast India: Implications for Lentic Ecosystem Governance

Abstract

Dumboor Lake (Gumti Reservoir) in Tripura, Northeast India, is an artificial lentic ecosystem formed by impoundment within the Gumti River basin. This study evaluated fish diversity, spatio-temporal assemblage patterns, conservation status, and principal anthropogenic threats across six representative stations sampled quarterly during pre-monsoon, monsoon, post-monsoon, and winter periods. A total of 62 fish species representing 7 orders, 21 families, and 41 genera were recorded. The checklist itself contains 50 taxa classified as Least Concern and 4 taxa each as Near Threatened, Vulnerable, and Endangered, corresponding to 80.65%, 6.45%, 6.45%, and 6.45%, respectively. Seasonal diversity was reported to differ significantly (p < 0.05), with the highest Shannon–Wiener index (H′ = 3.42) recorded during the post-monsoon period at the Raima confluence and the lowest (H′ = 2.18) during the pre-monsoon period at the dam forebay. The principal pressures identified were catchment deforestation, siltation, non-selective fine-meshed monofilament gill-net use, hydrological drawdown, and competition associated with exotic fishes. The findings indicate the ecological importance of river–reservoir confluence zones and support management measures centred on seasonal fishing restrictions, gear regulation, habitat protection, invasive-species control, catchment management, and community-based co-management while retaining the lake's fishery and livelihood functions and supporting sustainable lentic ecosystem governance.