Abstract
Aqua Research Restoration Center (ARRC) which was established in 1998 in Gifu Prefecture, has three Experimental Streams. Three streams have the length of approximately 800 m, and the bed slope from 1.2% to 3.33%. The Stream A is a straight channel and the Streams B and C have two meandering sections Electrical fishing surveys were conducted from July to December in 1999 in order to clarify relative variation in fish abundance among the three streams. The fish surveys resulted in the higher abundance in the Streams B and C than in the Stream A, and a relationship between habitat types and the number of individuals in the three streams were analyzed to specify the factors influencing the relative abundance of fish in the two types of streams. The habitat types were partitioned into a lotic zone and a water-edge from the lateral view of a cross section. The lotic zone was subdivided into riffles, pools, runs and glides, and the water-edge was subdivided into "vegetation" and "no-vegetation". A statistic analysis proved that several sequences of riffles and pools contributed to the relative abundance of fish in the Streams B and C to Stream A, however, the vegetation at water-edge did not function in the enhancement of fish abundance compared with the riffles and pools. These results will show that we should pay much attention to the habitat structure in the lotic zone in river works such as river restoration
