A couple months ago a friend came to town to visit.  So we went fishing.  While this friend is an experienced angler, he had not done much flats fishing, and had never poled a skiff.  Eager to learn all aspects of sight fishing on the flat, he offered to pole.  I gladly accepted his offer – time on the bow with someone else poling is always welcomed. 

Man, what a ride!  He was a quick learner, so poled a straight course, but he poled at warp speed.  His thought was that the more area he could cover the more fish we would see.  The problem was, most of what we saw was the back ends of fish, and last I checked they don’t eat with their tails.  A quick discussion of how fish see and hear convinced him to slow the pace, and we had some good shots at fish over the next hour. 

Sight, Sound, and Motion
The problem with his energetic poling wasn’t necessarily the speed, it was the motion.  Each time he pushed hard and fast on the pole, waves emanated from the bow.  These waves, although extremely small, announced our presence to any fish in front of us, and so all we saw were tails. 

Fish are able to sense their world in four ways – smell, sight, sound, and motion.  When sight fishing on the flats, I am concerned with the latter three, but mostly the latter two.  This is because, except in the clearest water, fish are unable to see great distances.  And even in crystal clear waters of the tropics, distance of sight is not comparable to what we can see in air.  Sound and motion are different matters, however.

Sound and motion travel through the water in the same way – as waves – and they travel very efficiently.  Sound, for example, travels through the water nearly five times faster then in air.  And low frequency sounds, like a thump on the boat deck, travel farther than higher frequency sounds.  This is why the knowledgeable angler is very cognizant of maintaining quiet on the deck of the boat or not splashing while wade fishing.

As the waves pass through the water, they displace water particles.  These movements are detected by the lateral line of the fish.  The lateral line is a line of cells that extends along the body of the fish from the head to the tail.  These cells have cilia that extend outward – passage of waves causes these cilia to wave or vibrate, and send a signal to the brain.  This is how a fish can feel a predator coming or a gamefish feels the movements of a swimming prey fish.  This is most efficient at close range.

For longer range detection of sound, fish make use of their inner ear system.  Fish have three sets of earbones (called otoliths) located in an inner ear system under their brains.  These earbones sit in fluid-filled cavities that are lined by cilia.  As sound travels from the water to the bone, the sound wave changes shape because water and bone are different densities.  This causes the otolith to vibrate, which stimulates the cilia, which sends a signal to the brain. 

So given fish sensitivity to sound and motion, their heightened sense of awareness in shallow water, and the rapid movement of sound through water, a stealthy approach is essential for any angler hoping to sneak up on fish in shallow water.

All material copyright Aaron Adams 2007, 2008, and beyond, unless noted.