Sorry to tell you, but you have under thunked it by a wide margin
that's a transducer which is a glorified loud speaker. The head unit sends an electrical pulse to the transducer that converts the electrical pulse into a sonic pulse (that's the "ticking" you can hear when the sonar is working normally) The sonic pulse returns to the transducer which converts it back into electricity & sends it back to the head unit. The head unit measures the difference in time between the pulse it sent & the pulse it got back, does a calculation & voila, works out the depth. All this happens very rapidly at anything from 50-800 times/second. By stitching all the individual depth measurements together, modern sonars are able to give you a "picture" of the bottom. But it's only an interpretation.
So in a nutshell, you need some kind of head unit. I think Lowrance do a basic gauge type that just gives a digital depth readout, it might output NMEA2000, I'd have to look.