You can often tell if a fish takes your nib, by watching the tip of your
floating line, or by watching your leader. If it hesitates or dips under
suddenly, you've either hung bottom, or a fish has taken your fly. But
strikes can be quite subtle, and fish can take and reject, or spit out your
fly very quickly, and unless a fish takes your fly in fast water or very
aggressively, many strikes go unnoticed.
Just as with any other kind of nymph fishing, any time that floating line
hesitates, wiggles, twitches, does anything that looks weird, and looks
suspicious, set the hook immediately. With nymph fishing, those fish are
going to take that fly, and spit it out really quickly, and you've got to
set the hook quickly. That doesn't mean wrench it way over your head and
break the tippet, but you've got to be quick, and just about this much,
just like you're going to make another cast, but do it quickly.
So, to help stack the odds in our favor, we use strike indicators. These
are little more than tiny bobbers. In fact, I once fished with a nymph a
whole day on the North Platt River, in Wyoming, with one of those big
plastic bait bobbers. I bought it in a gas station. It was a little clunky,
but it worked. Strike indicators turn nymph fishing from something that was
almost a black art, into one of the easiest ways to catch trout on a fly.
In fact, nymph fishing with a strike indicator is a lot like fishing a worm
with a bobber, and some of the deadliest nymph anglers are those who
started out fishing worms for trout. It's not that different, except the
fish spit out your offering faster.
Indicators come in all different colors, and sizes, and types; and most
people carry a variety of them. Different colors show up better under
different light conditions, so you should experiment. Also, carry a range
of sizes. The indicator should be big enough to hold your fly and weight
off the bottom, but not so big that it spooks the fish.
Most people these days use a big plastic or cork strike indicator. They're
really buoyant, and float all day long, but they do land kind of hard, and
there are some times when you want something more subtle. That's a time
when you want to use a yarn indicator. Yarn indicators on flat water like
this are very subtle. They don't land with a lot of commotion, and you can
really see the slightest twitch in a yarn indicator. So, they're one of the
best things to use on flat water like this.
Indicators serve another very important purpose. Besides being strike
indicators, they're drift indicators. You can't tell if your fly is
dragging under water, but you can watch your indicator, and if it begins to
struggle against the current, you know the fly is dragging and that you
need to mend line. If you watch your indicator, and make sure that it's
traveling at the same speed as the bubbles or debris in the current, you
can be pretty sure you're getting a drag-free drift. If it's not drifting
properly, mend a line to adjust your drift, or use a reach cast the next
time you present the fly. Exactly where to put your indicator on the leader
is part trial and error, based on how often the fly ticks bottom.
When you put an indicator on your leader, the general rule of thumb is to
have the indicator about one and a half times the water depth. You want
that fly to be riding just above the bottom, and the fly is seldom going to
hang directly below the indicator, so you want to estimate the water depth,
and then the water's pretty shallow here. I think it's about this deep, so
I'm going to go right about here with my indicator. I'm just going to put
the indicator on my leader here. This is the foam kind - it's got rubber
bands inside. You just twist it a few times, and that holds it wherever you
want it, yet when you change water depth, when you go to another place, you
can slide that indicator and move it to wherever you want.
This is only a general guideline, though, so play with the strike
indicator's position until you either tick bottom once in a while, or you
catch a fish.