The wary fisher knows the fish often see the approach, the waving fly rod, the ripples on the water from the splatting fly line or leader. And, we even have an awareness to wade slowly and quietly because the fish can ‘hear’ us?
Much like our own senses can combine to alert us to subtle changes, the above trout can detect changes about it that alert the fish not just to food but to predators….in particular us.
The lateral line is such a sense that allows fish to feel a presence than could be a food source or a threat, as well it aids the fish in navigation.
‘About the Lateral Line
Trout have inner ears, which allow them to hear sounds as we do. They also have lateral lines, special sense organs used to “feel” sounds. Lateral lines allow trout to hear sounds that are too low for humans to hear. Every trout has two lateral lines, one on each side of its body. A lateral line is made of a series of U-shaped tubes. Every time the water outside the U vibrates because of a sound, a tiny hair at the base of the U wiggles, which sends a nerve signal to the brain. The trout’s brain translates the wiggle into information about where the vibration came from. Trout use lateral lines to find food, escape predators and keep away from obstacles.’