In the stretch below the Herring Run again I suddenly saw, in the blank, dark water under gray skies, a wave, an eruption, a rushing ahead of a group of fish. Then they moved over to the side of the shallow stream, thirty or forty of them, and stayed there almost stationary for a while in deeper, slower currents where an overhanging shrub shaded the water. I threw a stick in their direction ... when it hit the water they wheeled wildly on their group axis, but stayed in the same place. Then in a minute or two they all made a break for open water at once, and I noticed that another group had come in unseen behind them. They would progress in this way, group after group, until they met the denser population below the fish ladders. One of them would come out first with a kind of flitting, darting, weaving forward against the current and the rest wheeled in behind it. I took off my shoes and waded out into the stream. A lead fish working its way back and forth with the current swung around as I came and fled back. I stood still for a while, noticing that the gulls I chased out of the valley had returned and were hovering over, chuckling, crying, mumbling, or barking like seals. After a few minutes of waiting the fish came right through and around my legs. My slightest change in posture would send the ones in front looping back, but they still kept coming. It was a quickening thing to see a fish race up in a long reach and then drop part way back again--a tentative, fast exploration of the current, the living current as perpetual as its own communicated impulses. One hundred yards or so upstream the alewives covered the stream bed where Stony Brook’s divided waters met. Some schooled slowly around below the unsurmountable falls, the rocks of death, the majority headed up the main stream toward the fishway where hundreds were massed, slipping and turning, arched in the white waters. Fishways are so designed as to allow the alewives an easier way to mount an incline, but they do have the effect of concentrating them in narrow quarters. The resting pools are compartments deep enough to check the velocity of the water and so permit the fish to wait before leaping on again. Even so the water roared down with great force on the alewives crammed in them. I could hardly hold my cupped hand against it. As they leaped up they were tunneled in spouts of water, and then they would flip through the boiling surface from one pool to the next, sometimes being thrown back to try again. XII The Imperfect Ladder