Brown trout can often cope with such extremes of water flow. In droughts, when the river is low, they may become nocturnal in habit. They will seek the cool still pools beneath the shade of overhanging trees, or the aerated pools beneath waterfalls. Then, come sunset, they will move into the shallows to feed. When the river is in spate the trout will seek the quieter corners, often amongst flooded bankside vegetation, where the flow is less.
Spate streams produce relatively little food, so the trout grow slowly.
Spate river brown trout can vary considerably in appearance, and experienced naturalists and anglers have long distinguished between the wild trout of particular rivers.