To find and catch river-dwelling fish, you need to think like one. Here’s how

BONUS: RIFFLE EFFECT

Most Canadian fly-fishing rivers create fish-holding habitat through a fairly predicable hydraulic cycle. It starts with fast water flowing over gravel and creating a riffle. Called rapids in larger rivers, this water is turbulent, oxygenated and shallow. That current scours the riverbed downstream, digging a deeper channel called a run, where the flow eases and the surface calms noticeably. As the run deepens, it slows into a pool. This slower water drops sediment at the pool’s downstream end, building up the streambed until the water constricts, accelerates and forms another riffle. And on it goes.