If you build it, will they come?

Building a fish ladder is one thing, but designing and positioning it so select fish can find and use it is a real challenge. It’s not like you can put up a sign pointing the way.

“The most important phase of fish ladder design is selecting the location,” Jourdonnais said.

Upstream migrating fish respond to their environment. For example, if they encounter strong currents in the middle of a stream, they may move nearer to shore or behind large rocks or debris where water typically flows more slowly.