Not sure how long your trolling runs were but if you catch a couple fish, mark that spot on your map and if you go 10 or 15 mins without a fish, make a big turn back over that mark.

If you don't have a map on your finder, I've been using Navionics map on my phone to mark spots too. My friends boat I use in CLE doesn't have fish finder or a map. Its been fun to try and sniff them out with his boat too.
Rickerd