Relationship between fish distribution pattern and geomorphology in the Konan area surrounding the southern part of Lake Biwa

Abstract

Fish distributions were surveyed in the Konan area surrounding the southern part of Lake Biwa from March 1998 to November 2000. From 879 localities, fishes of 16 families, 42 genera, and 55 species or subspecies were collected. Native fishes such as Zacco platypus, Zacco sp., Zacco temmincki, Gnathopogon elongatus elongatus, Pseudogobio e. esocinus, Carassisus auratus langsdorfii, Plecoglossus altivelis altivelis, and Rhinogobius sp. were collected at many localities confirming that they were widely distributed. The introduced fishes Lepomis macrochirus and Micropterus salmoides were also found in a large number of localities. The distribution patterns of individual species are related to geomorphology. The A-type pattern is represented by Zacco platypus, which is distributed in both delta and alluvial fan areas. The B-type pattern is represented by Zacco sp. and Gnathopogon e. elongatus, which are distributed only in the alluvial fan area. The C-type pattern is represented by Zacco temmincki, which is distributed in hilly areas. The D-type pattern is represented by Lepomis macrochirus and Micropterus salmoides, which are restricted to the delta area. The fishes that exhibit the B-type pattern were originally distributed in both the delta and alluvial fan areas, but they seem to have retreated from the delta area following the introduction of Lepomis macrochirus and Micropterus salmoides.