from my experience ‘fishing the bottom ‘ is a bit of an ‘old mans’ tale. I never fish the bottom and therefore don’t get as many snags. at macintoshs its a sandy bottom and fish really don’t like sand or mud in their gills. have lost count of how many fish I have caught at the top of the water column. another ‘old mans’ tale is that you can’t catch a porpoising fish again I have targeted and caught them. fishing the gut, the ‘experts’ say fish the bottom and the edges. often if you see the flow coming in both sides at top you will have an area of soft water down the middle where the two meet and salmon mostly take the soft option as they want to conserve their energy they will travel up the middle. another thing about gut fishing is to observe how fast the flow is and if you see stones moving with the current fish up in the water column as no fish wants to be hit on the nose by moving rocks. the main thing is to observe is where the fish are, the best way is to look for fish sign ie porpoising fish ,when you see one keep watching if you see another in the same area target the area as salmon mostly follow a path of lest resistance up the river.