Grayling and The Laws of Optics

Pliva’s golden grayling. Photo by Zeljko Prpic.

The date is approaching. Another trip to river Pliva is at sight.

Frustrating and absorbing in equal parts, Pliva offers some of the most challenging sight nymphing you can find anywhere. Even blind fishing with tungsten beaded nymphs is pretty special.

There is a particular stretch with big grayling up to 55/56 centimeters long —maybe more; I don’t know for sure, as seeing them and catching them are very different things, and I haven’t managed to catch one of the really big guys yet—,  that you often see actively feeding suspended like floating in thin air at depths up to three meters.

Every time I visit this place I think of a phenomenon called “refraction”. Have you ever noticed how a straight stick stuck to the bottom with its opposite end coming out of the water seems to be crooked at the point where it goes through the surface? That is the result of refraction. This source explains it in easy terms.

What does this issue have to do with sight fishing? Quite a lot in fact. The fish you are covering with your nymph is actually deeper and closer to you than it appears. It pays to take this into account, specially in places like Pliva, where due to the abundance of available food your nymph has to accurately follow the drift lane the fish is feeding in; it is very unlikely that a big boy leaves its lie to intercept a nymph even if it passes just a little farther away from its position.

So, any time you find yourself in a similar situation, cast with this optical effect in mind.

One comment on “Grayling and The Laws of Optics

  1. tonyking74 says:

    Snells law rules ko


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