Review of the Status of Freshwater Fish Habitats in the Han River Estuary Wetland Protected Area in Korea

The Han River Estuarine Wetland Protected Area is a representative estuarine wetland located in a brackish water zone influenced by both freshwater and seawater. As a designated military protection zone, access to the area is strictly controlled, and development is restricted. Notably, this area represents one of the major estuaries among Korea’s four largest rivers that has not been impounded by an estuary barrage, thereby sustaining high biodiversity, particularly in fish communities Monitoring of this region has been conducted through the National Wetland Protected Area Monitoring Program and the Inland Wetland Intensive Survey. Based on accumulated survey data, this study identified the freshwater fish fauna inhabiting the Han River estuarine wetland. A total of 3,427 individuals belonging to 49 species, 18 families, and 13 orders were recorded. No endangered species were observed. However, two invasive alien species -largemouth bass (<i>Micropterus salmoides</i>) and bluegill (<i>Lepomis macrochirus</i>)- were identified. Species dominance analysis showed that crucian carp (<i>Carassius auratus</i>) was the most dominant with 586 individuals (relative abundance [RA], 17.10), followed by mullet (<i>Mugil cephalus</i>) with 402 individuals (RA, 11.73). The family Cyprinidae showed the highest species richness with 21 species, followed by Gobiidae with seven species, and Engraulidae, Mugilidae, Hemiramphidae, Lateolabracidae, Centrarchidae with two species. By survey site, 32 species from nine orders and 12 families were found in Janghang Wetland, 21 species in Gongneungcheon Estuary Wetland, 25 species in Sannam Wetland, 13 species in Seongdong Wetland, 18 species in Yudo, and 17 species in Siamni Wetland. These findings highlight the ecological significance of the Han River Estuary as a biodiverse and relatively undisturbed aquatic habitat.