Re: Swift River Massachusetts
Red Owl hit the nail on the head. The Swift is a very technical river were presentation is key. The drift has to be perfect for fish to even be interested in the fly. It's not uncommon for a fish to follow the fly watching the drift. Sometimes they'll even nose bump it 2 or 3 times before striking. Trout eyesight is very poor compared to ours. They can't see detail of flies too well, but they sure can see a tiny bit of drag.
Fly size doesn't matter much during the warmer months at the swift. I catch dozens of fish there on my size 10 hopper pattern. My other top producing fly is a size 14 beetle. Sometimes I think the old locals like to mess with newcomers a bit by telling them to use size 32 midges on 10x tippet. It's easy to think the fly your using is too big with the fish being so educated. I always tell people on the river to try different flies and sizes. I've seen some big weird patterns produce very well there.
The only time I've had any luck matching a hatch is the midsummer sulfur hatch. Other than that I don't see any hatches going on big enough for the fish to key in on.
Great river and worth the time it takes to learn it.