Weird Sonar Images - Air Bubbles and Lines on Sonar On June 17, 2013If you see lines coming from the bottom to almost the surface at an angle, they are air bubbles. Notice the speed of 0.4 mph, I rarely see bubbles unless I am moving slowly. It is easy to confirm on calm days by watching the water surface for the bubbles. Both screenshots are bubbles.
Bubbles will always start at the bottom and seem to move to the right since the display prints their location higher as it scrolls.
Sometimes the fish give us clues on the sonar, in this screenshot I was jigging slow near the bottom and brought up the jig and noticed a fish chased it so I jigged with more aggression and caught more fish.
In this screenshot the bottom seems to get softer and the baitfish seems dispersed. The auto sensitivity has adjusted lower, I think the sonar “gremlin” (Lowrance software) feels there is too much information and it might be noise so it adjusts the sensitivity lower. Lowrance auto sensitivity is really good but not perfect, you may still get weird sonar images that are actually air bubbles on sonar.