EFFECTS OF DIAMETER OF PROTRUSIONS AND DISCHARGE PER UNIT WIDTH IN FISH LADDER FOR EELS ON MIGRATION RATE OF Anguilla Japonica

Abstract

 Studies on biology and environment of eels Anguilla japonica have been advanced in recent years. However, little is known about fish ladder for eels and migrating characteristics of eels. Especially, special fishways are necessary for demersal fish like young eels. This study was made to evaluate effects on migration rate of eels under the condition that diameter of protrusions and discharge per unit width in fish ladder are changed. It was found that migration rate increases with an increase of discharge per unit width in each of diameter of protrusions. Besides, sinuosity of eels are increasing, and averaged migrating speed is decreasing with an increase of discharge per unit width and diameter of protrsions.