This is not first hand knowledge, but when I am spening time on Winnisquam (handful of weekends per year with non-fisherman..booooo) most of the salmon/trout trolling boats I see are working in the depths around Pot Island.
I was just there a couple of weeks ago. The area around Pot Island is a good spot to try. Also try the area around bouy #8 just south of Pot Island & bouy #3 to the north. I marked & caught a lot of fish there. If you are on the water at first light or at dusk, fishing the railroad tracks on the west side is a must. I fished 50'-70' of water, down 30'-45', 2.0-2.5 mph. I used mooselooks, top guns & DB smelts. The best colors were gold, gold & orange, white/red dots and of course the DB smelt-N.H.guide.
Good news is... pretty much wherever you go on this lake (in deeper water) you're going to catch lakers. They may not be too big, but you'll catch them everywhere. I can't seem to get away from them on Winnisquam. I haven't had the numbers we get in the big lake, but it is typically a steady catch none-the-less.
Pot island probably is a good bet to try...
Pink and silver worked well for me last time I was out there...
Don't hesitate to fish late afternoon. I've caught bigger fish at that time on Winnisquam than in the morning.
