sonar and fish identification Posted on October 05, 2019
Using sonar, down imaging, Lowrance, Humminbird, and Aqua-Vu to study fish
Using sonar, down imaging, Lowrance, Humminbird, and Aqua-Vu to study fish
Mostly fun and a little education.
Just another example on why down imaging helps sonar interpretation. The weeds look similar to fish.
In this one the fish look like weeds.
I use sonar to find fish every time I go out but sometimes the fish can hide. Two good examples are boulders and steep drop-offs. The sonar beam is reflected off the bottom on steep drops and off the boulders and the fish can’t be separated.
I drove over this drop-off that had boulders and didn’t see any fish with either the Humminbird or the Lowrance.
I stopped on the edge and used the Spot Lock feature of my Minn Kota trolling motor on the edge and dropped my Aqua-Vu camera down and found these crappies but not just here but each time I moved along the edge there were more crappie.
Even the down imaging couldn’t separate the crappies from the boulders while I was sitting over them.
Notice the crappies are very close to the boulders in the video.
They did bite and they posed for the camera before being released (I had fresh walleye back home).
I produced this short video using sonar, down imaging and an Aqua-Vu to show you how I interpret sonar.
Click on image to view video
Watch the short video to get an understanding why weeds are important for fishing.
Ever wonder what to do when you are slowly moving jig or rig fishing and lose the fish on sonar?
I had these fish near weeds located with down sonar (2D and down imaging).
If they disappear I look at the side imaging on a different screen to see if they are left or right. Like this image.
I place the cursor on the fish on the side imaging and create a waypoint and then move the boat to the fish before they move too far. It is easy, once you catch a few fish this way you add it to your fishing tools.
Interpreting sonar, down imaging and side imaging is very difficult. I have 3 great images to use as examples for teaching interpretation of sonar.
The left side imaging is showing the drop-off as dark (yellow arrows point to the drop-off on the map and side image). Bright is the strongest return and black is none. Since sound goes in a straight line the drop-off is dark.
The red circle is showing fish on the shallow side and I think they are about where the red arrow is pointing on the map. I would mark a waypoint on the side image and cast to the fish since they are shallow. Notice the boat is in 2.9 feet.
The next image shows the drop-off as dark (red circle) and fish are suspended near the drop (yellow arrow). Fish show up well on side imaging since they show up as bright on the dark background. Hard bottom is also bright which makes fish difficult to see on bright background.
This is an amazingly clear image of boulders (green arrow) next to trees (yellow arrow) that slid from the bank into the river.
The red arrow shows a fish in the trees and the white arrow shows a small drop-off.
Don’t miss supper, get better at sonar and fish where there are fish. Use the splitscreen sonar and down imaging and compare the two and you will become an expert.
Down imaging has a narrow wide cone and the 2D sonar has a round cone so they view targets differently and comparing the two makes interpreting sonar much easier.
This image is showing trees and the 2D sonar on the left is difficult to interpret but the down imaging shows the trees well.
This image shows fish on the side of a boulder but the down imaging shows 2 fish and I get much more excited seeing two fish than one.
This image shows 2 bait balls in weeds (yellow and green arrows) that the 2D sonar looks like weeds.
This image looks like stacked fish because of the arches but it is a common when you have posts or trees.
On this image the bait ball and the larger fish near it are missed with 2d sonar.
I see images like these everyday on the water since I usually run down imaging with 2d sonar. If you miss a fish on sonar you may miss supper.
