淡水魚の水田周辺における一時的水域への侵入と産卵

抄録

Paddy fields and ditches around irrigation creeks constitute temporary waters flooded only in summer. In order to consider the significance of such temporary waters for fishes, the movement and behaviour of fishes in temporary waters and a permanently filled creek were investigated near the town of Yagi, Kyoto Prefecture. Among twenty-three species identified in the study area, seven species frequently entered the temporary waters, six of which utilized these waters as spawning sites. Two species were seldom found in the temporary waters, in spite of their abun dance in the permanent creek. The remaining fourteen identified species were rare in the study area. Fishes which frequently utilized the temporary waters for spawning had a similar reproductive habit, i. e., they scattered many eggs widely and showed no parental care. It is considered that many fishes, including juveniles, were foraging on the plankton which became abundant in the temporary waters after irrigation. It is surmised that newly emerged habitats of temporary waters with high productivity serve for the maintenance of a rich fish fauna in irrigation creeks.