That is a possibility slabbacks as anything that reflects some of the sonar is also blocking passes by or through it from reaching anything underneath it as well. However I would expect that most of that is due to a softer bottom in that area. We see where some of that fish/structure area reflected enough sonar to produce a second sonar return, so that spot was harder than what was directly before and after it.

Some things to keep in mind here are not only the color pallet being used but also the sonar frequency, beam width and any menu settings that can affect how the bottom is shown (Sensitivity, any sort of WhiteLine or filtering, TVG or surface clutter settings). Even things like the shape of the bottom terrain can affect how thick the red line is shown. In Rickie’s last pic above; some of the reason for the thicker red line in that area is due to the shape of the bottom. With a slope/drop-off the sonar is receiving a strong sonar return from more than one water depth at the same time and so shows this as a thicker red line. If the same bottom were flat it would show as a thinner red line. Remember, the sonar will try and show all sonar returns from the circular sonar beam and while over a slope it is receiving sonar returns from the shallow, middle and deeper ends at the same time. If they are all of the same density, they would all get shown as a thicker layer or line as the deeper end of the slope is farther away from the transducer – which gets shown as a deeper water depth for us. Of course, a slope or drop-off reflects less sonar directly back to the transducer and so should get displayed as a weaker sonar return color and would be unless the Sensitivity of the unit were turned up too high to show this. Of course when you turn down the Sensitivity in your unit so that it does show this (or even to the point that it could show the difference between bottom types); you may have also set it so low as to not show any fish, which most would never do.