A nation-wide survey of introduced fish fauna in large river systems (>4th order streams, 28 sites, 9 river systems, total area 75,000 km 2 ) was conducted from July 1999 to January 2000 in South Korea. A total of 62 fish species (12,317 individuals, 16 families) were collected from two sampling programs. These included 32% of 194 known freshwater ichthyofauna of S. Korea. Dominant and subdominant species were Zacco platypus (16.2% relative abundance), Acheilognathus intermedia (10.6%), A. rhombea (7.2%), Opsariichthys bidens (7.1%), and Carassius auratus (6.9%). Fifteen exotic fish species have been introduced in S. Korea for food sources and about 120 species for aquarium use since the 1950s. In this study, five of the introduced food species were collected (Carassius cuvieri, 24 sites; Micropterus salmoides, 13 sites; Lepomis macrochirus, 7 sites; Oreochromis niloticus and Cyprinus carpio, 3 sites). C. cuvieri and M. salmoides were common (subdominant at 5 sites) and followed by L. macrochirus. These species were spread widely (93%; 26 sites) over all the study sites. Future research must consider the impacts of these exotic fish on natural ecosystem structure and function.
Internat. Rev. Hydrobiol.