Shooting&Fishing: In less than five hours the river shot up and turned into a brown stew

Most years it seems to be a dribble by late July. In "the old days", they said, the land acted as a giant sponge, soaking up the water in winter and allowing it to leach out in summer, which kept the height fairly steady. Then came the big forestry plantations and improved land drainage and the sponge effect disappeared.

Rain and snow melt ran straight off into the new ditches and whoosh..., what would once have been a steady summer-long supply of water was flushed out to sea in a few weeks. So these days the river goes up and down like a yoyo. As soon as rain falls it is drained away. One day it shoots up a foot, the next it's down two.

But this year, thanks to fairly continuous rain in the hills, we've had a reasonable flow of fish and water. Until, typically, friends took a beat for a week, and the heavens opened. In less than five hours the river shot up and turned into a brown stew. Come down tomorrow anyway, they said; it may clear a bit and Smithy (the ghillie) says he'll teach us how to worm. Aha. Now I have caught trout on worms but I have never quite known what I was doing and never been shown by anyone who really knew how to catch a salmon. (There was some question about whether it was entirely legal. But it was thought that worming on this occasion, came under the heading of an "educational demonstration").

Smithy was keen to dispel any idea that worms were some sort of fish magnet or that to worm was to cheat. The late law Lord "Tiger" Morison had, after all, spent a lot of time rowing with his local river board over his "absolute right" to fish with a worm. Worming was almost more skilful, Smithy hinted, than casting a fly. "Cast a fly and the river will do the rest," he said, slightly scoffingly (the local tackle shop that morning had been full of ghillies buying lead wire weight for their worms, all loudly announcing they were going sea fishing). But to fish with a worm you have to work at it, said Smithy.

Only experience and trial and error could tell the amount of lead needed to take the worms to the bottom. Dropping them in the right spot upstream so they came down on the edge of the main stream and the slower water where the fish lay proved frustrating. And then there was "the working of the worms"; dancing them down the river bed, lifting the rod just enough to keep the weight and bait on the move, feeling for the famous "three knocks", tugs really, of a salmon, but trying to remember not to strike at the first or even second knock. How would we know it's the right sort of knock? I can't teach you everything, said a sniffy Smithy. But you'll know. You'll know.

• This article was first published in The Scotsman on September 25, 2010