I presume the main reason anglers use downriggers and electronic depth/fish finders is because salmon have become relatively scarce, making it more difficult and time consuming to catch one. It's hard for me to realize that during the early years of Puget Sound salmon fishing, most recreational angling was done with skiffs - with oars, not outboard motors - and mooching gear. There were many dozens of boathouses that rented the skiffs, so the Sound was covered with hundreds, if not thousands of small salmon fishing boats. And they caught salmon. Because salmon were abundant.