THE COMPOSITION OF INVASIVE FISH SPECIES AND ECOLOGICAL RISK ASSESSMENT IN LONGYANGXIA RESERVOIR

To understand the current composition, ecological risks, and potential distribution areas of high-risk invasive fish species in the Longyangxia Reservoir, and to develop targeted prevention and control measures, this study conducted systematic field investigations in the Longyangxia Reservoir and the surrounding Yellow River Basin in May, September, and December of 2023, as well as May and July 2024. These were complemented by a literature review to systematically summarize the current fish composition and ecological types of invasive fish in the reservoir. The AS-ISK tool was used to assess the risk level of each invasive species, and the MaxEnt model was used to predict its potential distribution of one typical invasive species, <italic>Pseudorasbora parva</italic>, across the Longyangxia Reservoir Basin. The results showed that: (1) A total of 21 fish species belonging to 4 orders, 6 families, and 16 genera were collected, including 11 invasive species. Based on the index of relative importance (IRI), 6 dominant species were identified, 4 of which were invasive: <italic>Carassius auratus</italic>, <italic>Pseudorasbora parva</italic>, <italic>Oncorhynchus mykiss</italic>, and <italic>Hypomesus olidus</italic>; (2) Ecological matrix factors revealed that invasive fish species were predominantly characterized by terminal mouth positions (<italic>R</italic>=0.64), adhesive egg production (<italic>R</italic>=0.91), omnivorous feeding habits (<italic>R</italic>=0.72), and benthic lifestyles (<italic>R</italic>=0.45), with most being resident species (<italic>R</italic>=0.73) adapted to calm water environments (<italic>R</italic>=0.91); (3) According to the AS-ISK assessment, there were 5 high-risk, 2 medium-risk, and 4 low-risk species, with the top 5 highest-risk species being <italic>Hypomesus olidus</italic>, <italic>Pseudorasbora parva</italic>, <italic>Cyprinus carpio</italic>, <italic>Oncorhynchus mykiss</italic>, and <italic>Carassius auratus</italic>. Compared with historical data and incorporating weather predictions, the number of invasive species is expected to continue increasing; (4) The MaxEnt model prediction indicated that high-risk area of <italic>H. olidus</italic> is mainly concentrated in the Longyangxia Reservoir, Liujiaxia Reservoir, and the Yellow River Basin between the two reservoirs, while the reservoir tail and upstream areas represent low-risk zones. The study highlight <italic>H. olidus</italic> as the key species for prevention, with the Longyangxia Reservoir tail being the primary focal zone. These findings provide data support and theoretical references for the supporting green and sustainable fisheries development in the Yellow River Basin.