You can’t fish too small a fly for salmon in low water conditions. You look at the the vast display of flies in front of you and pick a few size 12 doubles and a few 1/2 inch tube flies. Go smaller, they will be more likely to come to smaller patterns than a large size 10 or 12. Size 14 or a size 12 Nordic double sparsely dressed, another great option is size 16 micro trebles these are deadly when fished on full floaters with a fluorocarbon to get them just to sit in the surface film. Rod and line choice are critical as well, switch rods or even a single handed rod is advisable with a 7 weight floating line.
One thing you can be assured of is the fish will see your fly, they have great eyesight even when dibbling your fly through the white water in the streams. Yes dibbling for summer salmon is a fascinating way to catch them, walking quietly down through the white water rapids dibbling your fly behind the big boulders and rocks can produce some frightening takes.
My friend Donald caught a 26lber off the river Dee a few years ago behind a rock that you would not have thought the fish could sit, on the fly below.
yes all 4mm of it, so when you are out there this summer choose a few small patterns and give them a go.