When Baitbucket took me trolling on Quabbin we saw fish feeding one the surface in June as we were headed across the reservoir. I would think it was too warm on the surface for salmon, but maybe not juveniles? IIRR Baitbucket seemed to think it was a possibility. And as many of you know salmon, trout, and catfish are physostomous. For those of you that don't know, this means they have a pneumatic duct that connects their air bladder with their alimentary canal. Allegedly they can quickly come to the surface out of deeper water as in after bait fish in warmer water, belch out the build up of gas in their bladders, and go back down to the deeper water. That said I have caught rainbow trout that had trouble going back down after they got off the line.
At the mouth of the river at Sebago in the Spring, it's East to West unless you want a beating from the rest!