18 巻 (2012) 2 号 p. 29-35
The distribution and the habitat characteristics of kitanomedaka in the canals and the ditches around Kahoku-gata, Ishikawa, Japan were investigated in September and October 2001, August 2002, November 2003, during the transient period from irrigation period to non-irrigation period. The investigations revealed the distribution of medaka habitats in the lowland around Kahoku-gata. In the study areas, the habitats were not continuous but rather segmented and isolated. The multiple linear regression analysis indicated that the water surface coverage of vegetation, water surface width and flow velocity were correlated with the medaka population during the non-irrigation period. During the irrigation period, the canal type was correlated with the medaka population although the determination coefficient was very low. In addition, some habitats of medaka in the middle of the Unoke River basin were also reported based on the investigation conducted in December 2004 and January 2005.