As a south island fly fishing guide I look forward to the start of a new season. One of my favorite aspects of this time of the year is being able to use larger than normal nymphs. Early season on Nelson backcountry rivers we find there are a lot more stoneflies and creepers in the increased spring run off flows. It is not unusual for me to use a stonefly pattern as large as size 6 to fish sitting deep in fast water. There is often no other way to get the depth required without adding lead or tungsten putty to the tippet. You can build and enormous amount of weight into a size 6 stonefly!
A tactic that I and many others use is to truck and trailer a smaller unweighted nymph behind our large fly. This gives us the chance to get a small fly deep where it needs to be. Make the point fly as attractive as possible by choosing a pattern with movement ie. a soft hackle.
With heavy flies lead in to the fish is critical. Too short and you wont get depth, too long and you run the risk of drag. To a fish it is very unnatural to see its food dropping through the water column from above. So we need to be at the fishes level as the nymph drifts past. This is where short casts are problematic – not to mention the huge splash a tungsten or double tungsten nymph makes as it hits the water! Even worst are long casts. If you have poor line management skills a long cast is fatal. If you feel that you need depth it would seem the logical thing to do would be to throw you cast as far up stream as you can to allow your fly to sink. This can work by it is seldom done without the use of a mend either aerially or from the surface of the water. If a mend is not preformed the drift will more than likely drag. Which almost more than anything else will make a fish spook.
I will leave it at that for now; its not good for my business to be giving away too many of my secrets. But get out there early on this season the fish will be just a little naive and feeding hard when the conditions allow. There is almost nothing better than getting that stonefly to lodge in the mouth of a great opening day fish.