Simrad Screen Shots

 These are a few scattered Stripers on a 25 foot flat with some catfish mixed in. Many of my clients want to understand how I know how large a fish is by looking at my unit. Sonar works kind of like a small pen-like flashlight. If you were to shine the light straight down the cone angle is very tight near the light [or transducer] then spreads outward the deeper it gets. The closer the object is to the center of the cone, the better the reflection will be. The fish at 8 feet on the left of the screen is directly in the center of the cone. It shows almost a perfect arch and has some color in the core of the fish. The fish at 12 feet just to the right of the first fish is off slightly to the side of the center of the cone. It is more flat in nature and barely has any color in it. Then the yellow flat signature to the right of it is on the outer edge of the cone angle, displaying no color. The size of the fish are relative to how far the fish is from the transducer. The fish at 8 feet appears to be nice but it is only 8 feet from the transducer. The closer it is to the transducer the bigger it appears. It may have been a 1 pound fish. Now if that same fish was in 24 feet, the arch would have been about a third of that size. Consequently in determining how large a fish is you must take into consideration how far it is from the transducer. The Stripers on the screen were probably 2 to 4 pound fish.

 This is a brushpile with crappie holding on top of the brush and next to the brush. You can see tiny arches on the left side of the brush, on top of it and a suspending school just to the right of the brush. You can tell that it is brush because it is connect to the bottom. If it were bait for example the fine yellowish line that is the surface of the bottom would come underneath the object just like it does underneath or the two catfish laying near the bottom.

I took this shot while looking for Stripers. There was about 3 to 4 acres of bait that I was searching to see if there were any Stripers that might be feeding. I looked for about 10 minutes but all I could find was bait. The small vertical arches that are stacked vertically are white perch. The school of bait on the left side of the screen is 4 to 5 inch Gizzards and the small school near the middle of the screen is Threadfin shad. Threadfins always look kind of like a rocket ship, they have a point on the top of the school, very dense center then have two downward "tails" underneath the school. The way I know what they are is that I have been throwing cast nets on bait for the last 25 years and I recognize the correlation of what I catch in the net to the shape and size of  what I see on my depth finder. When I target specific types of bait I throw only on what I know to be what I want. That 10 foot 1 1/2 pound net gets heavy after 20 to 30 throws!