Attraction-flow-type Fishway
The attraction-flow-type fishway is made of attraction flow channels in the center portion and stair fishways (fish ladder portions) on both sides. Fish are tempted by the flowing water in the attraction flow channels, and travel upstream via the fish ladders on both sides. Their behavior can be seen through an observation window.
Structure of stair fishway
Fish heading upstream through the attraction-flow-type fishway(viewed from observation window)
Cobblestone fishway
(the land side of the right bank fish ladder portion)
One of the stair fishways was made as a cobblestone fishway; cobblestones are laid thickly in the pool to facilitate-upstream travel of benthic fishes, shrimps, and crabs.
Ayu migrating upstream at the Nagaragawa Estuary Barrage
- No data have been provided for fiscal 1995. Fish count could not be obtained because the gates were fully open on May 21 and later for preparation for full-scale operation.
- For fiscal 1996 through 1999, measurements were taken in cycles of ten-minute visual inspection, ten-minute intermission and ten-minute visual inspection. The measured count is estimated to be a half of the fish count on the land side of left bank attracting-flow-type fishway.
- In fiscal 2000 through 2005, the left bank attracting-flow-type fishway was divided transversely into two sections. Measurements were taken alternately in either section every other day (measurements were taken continuously using VCRs). The measured count is estimated to be a half of the fish count on the land side of left bank attracting-flow-type fishway.