In the old days of fishing, we all relied on our “sixth sense” to find fish. We used super x-ray glasses to see the fish under water and even became good weather forecasters… all because we needed to find where the fish are! Fortunately, technology such as sonar touched our favorite pastime in a good way. We now have very accurate equipment that finds the fish we’re looking for. We can now see deep under water (without our x-ray glasses, of course) to avoid obstacles and end up in the best place to catch our limit. So, we can put all our “other” techniques to rest. For those of you who discovered the Lowrance Fishfinder, below you’ll find a few tips for reading the screen of your fishfinder so you can find fish quicker and more reliably.

Before we start, please make sure everything is installed correctly. Take the necessary time to “go by the book” this time!

• Once you’re up and running you’ll notice the display shows a standard numerical value and metric value in the upper left corner. This indicates the water depth directly under your boat. For best results, make sure the automatic mode is active. The display may also show water temperature and boat speed.
• At the bottom of the screen is a line that extends the width of the screen. This line represents the bottom of the lake or river. In the case of rocks or other hard material, the line may be thick and dark. On the other hand, if the bottom is soft, a thinner, lighter colored line will be visible. A flat line represents a flat bottom that inclines and declines based on variations of the bottom surface. You’ll notice the depth reading on the display will change in relation to the readings from the bottom surface.
• As you’re slowing moving along, notice the objects just above the line on the display. These provide an idea of what objects are present on the bottom. Trees and brush for example, will show as vertical lines while vegetation will show as thicker, more obvious indicators with irregular shapes.
• You’ll see fish located between the bottom line and the top of the display. Objects shaped like arches are fish, and the size of the arches correlate to the size of the fish. Bear in mind the location of the objects. They could be near the bottom or just above trees or vegetation.
• As mentioned above, troll slowly to allow the fishfinder to perform at its best. If at any time you’re stopped or stationary, the objects will appear as lines.
• Small fish usually will not appear as arches.
• Adjust the unit’s sensitivity as high as possible without presenting too much noise on the screen that may show as clutter.
• Study the shapes of the objects. For example, a school of fish may appear like a stack of blocks.
• At the top right of the split screen surface clutter may show up, extending many feet below the surface indicating bait fish, algae, plankton, air bubbles or waves.

Portable fish finders operate by using SONAR (SOund Navigation And Ranging). It emits sound waves into the water. These sound waves move at a constant speed. When they reflect back to the receiver the time between when the signal was sent and when it returns is measured to give the depth of the object the sound wave bounced off of. Any fish finder can also be used to test the depth of water and map the bottom. How this is graphically represented will depend on your specific model. Some will give a numbers readout, others will show the contours of the bottom and still others will only show “fish.”

It’s important to understand two things about fish finders. The first is that a “fish” is generally any object that floats above the bottom. It could be a piece of vegetation or debris. This doesn’t mean they aren’t a useful tool when trying to find a good spot, it only means that readings should be taken with a grain of salt.

The second thing is that, just as with any tool, using a fish finder takes practice. Stopping the boat when you see your first fish hit isn’t necessarily the best course of action. After a few hits a small, investigatory circle will give you a better idea of what the area looks like, how deep the water is and how deep the fish are.

Along with practice you’ll want to play with the settings on your finder to get it to work for you and the fish you are trying to find. Most finders can have the “window” adjusted to show an area between certain depths. The first ten feet or so of water rarely has fish, and many anglers set the window ten feet or so above the bottom. This can cut down the noise, or useless information, that the sonar returns.

Most fish finders have a fish identifier, or fish ID, setting that tries to identify certain types of input as a fish. This is good for beginners, but as you get more used to your finder turning this off will allow you to all of the information and interpret it yourself. This will allow you to see greater detail and interpret it yourself.

In the end a fish finder is not a magic wand to bring fish up from the unseen depths, but it does give you information that you’d have no other way to access. With a little practice you’ll learn to use it to more quickly find good fishing spots and have more productive outings.