Have you ever noticed that when trolling, you only mark fish on your graph going in one direction. It happens more frequently than you would think. In this article, we will discuss what we feel to be the reasons why this occurs. These are our theories as to why this happens.
The Obvious
The most obvious reason why you quit marking fish is because they have moved. They may be riding the underwater currents. They could be following bait fish which are on the move as well. The quarry may also have moved to get away from increased boat traffic. Anyways, the obvious reason is that the fish just aren’t there anymore.
Effect of Currents
Underwater currents such as those caused by winds and the Coriolis effect play a huge effect in the day to day lives of fish. Specifically, current direction influences the position fish will take into relation to it. For the most part, fish most always like to face into the current so that water flows through their mouths and over their gills. In this position, fish expend way less energy to breath. Water flows over their gills naturally. So why is this important for marking fish on your graph?
Underwater Noise
It’s our belief, that sound travels with the current. If you are trolling up current of the fish, the fish will hear you before you get there and scatter. Water is dense and is a great medium to carry sound. For reference, the speed of sound through air is 767 mph. In water, it’s about 3 times faster at 3,315 mph. Have you ever slapped your hand down on to the water’s surface before? It is very dense like hitting a wall. Water is hard to compress.
How Sound Travels
Just as in hydraulics, like brake lines, pressure applied to one end of the liquid column or end is transferred to the other end almost instantly. Sound travels much the same way, almost instantly (3,315 mph or 291,720 feet per second). Add current and it’s like applying pressure in one direction; much the same way as hydraulic brakes. The upside of the current pushes the sound to the downside of the current almost instantly. The fish can most certainly hear and/or feel this through their lateral lines and/or neuromasts .
Correct The Situation
In conclusion, there are several reasons why you may mark fish going in one direction, but not the other way. It happens. The trick is to figure out why its happening and how to correct the situation. There will be days when it’s easy to figure it out. There will also be days when it’s near impossible. Either way, as it always seems, the fish will tell you if your doing it right.