In his book Old Yukon, written in 1938, Judge James Wickersham tells a story that illustrates the remarkable jumping ability of migrating grayling. Wickersham could not vouch absolutely for the truth of the story but he obviously believed it true and even made a drawing to portray the event.
Three Alaskan gold prospectors built a log dam to block completely a small stream. Using canvas, they built an eighteen-inch diameter pipe to carry the water flow some 200 feet downstream and attached a four inch nozzle to the lower end of the pipe. A screen placed at the upper end of the pipe kept debris from entering. Since there was no reason to do otherwise, they allowed the water to flow through the pipe even when not using the water for mining.
One morning they approached the pipe to find three or four large grayling lying on the ground beside the nozzle. At the time the nozzle was about five feet above ground and was jetting water out horizontally approximately eight feet.
Then, much to their surprise, the prospectors found another hundred grayling trapped inside the pipe. The prospectors realized that the upstream migration of grayling had commenced during the night. Each fish swam upstream until there was no other way to proceed except to jump up through the water flowing out of the nozzle and into the pipe. As Judge Wickersham noted, it is amazing that better than 95 percent of the grayling successfully did it.