Changes in Fish Fauna and Community Analysis in Upo Wetland Protection Area, South Korea

Upo Wetland is a representative wetland protection area in Korea, recognized for its high conservation value as a habitat for various organisms. However, the presence of livestock farms and farmland around Upo Wetland has led to the inflow of various pollutants, resulting in mass fish deaths. To protect and manage the freshwater fish residing in Upo Wetland, we analyzed the changes in fish fauna and community structure using survey data collected from 2003 to 2024. The survey confirmed the presence of 13,149 individuals belonging to 12 families and 30 species of fish, with <i>Pseudorasbora parva</i> being the dominant species, followed by <i>Carassius auratus</i>. <i>Micropterus salmoides</i> and <i>Lepomis macrochirus</i>, invasive alien species, were prevalent in 2003 and 2009 but showed a rapid deline after 2021, while <i>Erythroculter erythropterus</i> increased significantly. Another alien species, <i>Oreochromis niloticus</i>, appeared intermittently, and the <i>Rhodeus uyekii</i> and <i>Aphyocypris chinensis</i> have not been observed since 2006, leading to the presumption that they have disappeared from Upo Wetland. <i>Rhinogobius brunneus</i>, <i>Rhinogobius giurinus</i>, and <i>Tridentiger brevispinis</i> have only been recorded since 2021, suggesting they were introduced after the 2020s.