Sonar problem with braided Dyneema downrigger line

I put some Scotty 250 pound test Dyneema braided downrigger line on one of my downriggers, hoping that it would have less drag and less hum.  However, sonar returns from the line created streaks across the portion of my sonar screen above my downrigger weight which made it difficult to see returns from fish in that area.  I had never had that problem before.  I switched to another downrigger which had a standard stainless cable, and the problem completely disappeared.  Has anybody else had this problem, or have any theory about what may be causing this problem?

I've never had that problem. The only thing I can think is that the line is sending out high frequency sound waves in the same range as the sonar return. Are you running a snubber if any sort? I'd try to dampen or change something very slightly. Double up the last few feet like with a Bimini twist. Add even a small split shot or something a few inches up maybe? It'd seem, like a guitar it'd have to be the exact right length of line or tension  to get a return at the right frequency.  That's very odd.

Or try 50 to 100# standard braid

Can you change the sonar frequency? 83/200