EFFECTS OF LAYOUT METHOD OF PROTRUSIONS IN FISH LADDER FOR ANGUILLA JAPONICA ON MIGRATION RATE

Abstract

 It is estimated that the number of eels (Anguilla japonica) is decreased by the worse of river condition, thus fish ladder for eels is necessary in the river. Grid and zigzag type are known as how to put bunch of brushes and round protrusions on European fish ladder for eels. However, it is not cleared that which type is better and it is guessed that there is no studies about it. This study was made to evaluate effects on migration rate of eels under the condition that how to put on protrusions and discharge in fish ladder are changed. It was found that migration rate of eels and averaged migrating speed of eels keep advancing in zigzag type than grid type in this experimental range. Therefore, it is assumed that migration rate of eels improves in zigzag type.