SPECIES COMPOSITION, SEASONAL VARIATION, AND CONSERVATION STATUS OF FISH ASSEMBLAGES IN THE UPPER TIEN RIVER, DONG THAP PROVINCE, VIETNAM

Tóm tắt

The present study investigated the species composition and spatial distribution of fish assemblages in the upper reaches of the Tien River in Dong Thap province. Samples were systematically collected at four fixed sites within the headwater basin from March to August 2025. A total of 86 species, representing 59 genera, 36 families, and 14 orders, was recorded. Among these, members of the order Cypriniformes exhibited the greatest species richness (25 species), followed closely by Siluriformes (22 species). Species assemblages displayed marked seasonal shifts, with composition differing between the rainy season and the preceding dry period. Importantly, the survey documented a number of threatened taxa. Several rare species appear on the IUCN Red List (2025) and the Vietnam Red Data Book (2024), underscoring the conservation value of this riverine system. Furthermore, analysis of encounter rates revealed that most species had low to very low frequencies of occurrence, pointing to either naturally sparse populations or anthropogenically induced declines. Overall, these findings provide a baseline for biodiversity monitoring and resource management in the upper Tien River. They highlight the need for integrated conservation strategies that account for seasonal dynamics and protect vulnerable taxa. Continued monitoring is therefore recommended to detect long‐term trends and to inform adaptive management in the face of ongoing environmental change.