EVALUATION OF WIGHT OF PARAMETER FOR EGG-LAYING OF AYU AND PREDICTION OF EGG DENSITY PER UNIT AREA

Abstract

Hydraulic structures such as a dam, weir and water gate affect on the flow depth, velocity, bed shape, water quality and so on, so that the hydraulic structures may affect on the water environment for plants and aquatic lives in an around rivers. Therefore, before construction of such hydraulic structures, it is necessary to conduct the environmental assessment. However, the accuracy of the environmental assessment is not so high at present, because it is not clear that what is the most suitable parameter which affects on the water environment. In this study, the most suitable parameter for spawning of Ayu were selected from the several values such as water temperature, velocity, flow depth, incline, BOD, COD, pH, SS and so on, on the basis of a principal component regression analysis. It was found that the most suitable parameters are temperature, velocity, flow depth and SS.