I just read this piece:
http://www.dosits.org/animals/produce/2f.htm
Given that sounders go from about 28kHz to 200kHz, fish generally should not hear them or sense them through their lateral line however,
I know some people swear that fish won't bite under a transducer, and others say the fish don't care.
Does anyone have any stories or done any tests to sway the argument one way or another?
(Lots of people say just turn it off to be sure by I have a combined GPS/sounder which I like to keep on for the GPS features)