Abstract
Changes in the fish communities along the coastal lagoons termed “Naiko” surrounding Lake Biwa were investigated using a survey of preserved specimens. The survey was performed at 7 institutions or museums, and the results revealed that an indigenous species of fish that was abundant before the 1960s is now a rare species. However, some of the Naiko lagoons where these indigenous species were observed have been replaced by reclamations used as rice fields. Sampling records demonstrated a drastic change in the recent fish communities, and this has been exemplified by the sharp decrease in the unique indigenous species and synchronous increase in the exotic Largemouth Bass (Micropterus salmoides) and Bluegill (Lepomis macrochirus). Fishes observed in the lagoons were basically classified in terms of migration type (sensu Hosoya, 2005). Many of the species observed fell into 2 categories: the Naiko-rice field migration type and the Naiko resident type. Until the 1960s, the original fish communities in the Naiko lagoon comprised various migratory species that belonged to the main Naiko resident type. This implies that such diverse original fish species should be restored in order to reconstruct the original aquatic environments.
