My friend, Henry Kanemoto, sent me a photo of 3 size 16 hooks laid out on a scale with 1/16 inch hash marks. It is most revealing. I was reminded again about the importance of knowing the hooks that one ties on.

When we were shooting “Nymphing” in the summer of 1982, I noticed that the size 16 fly I had tied to match the PMD nymphs on Armstrong Spring Creek looked a size to big. Measuring the nymphs put them squarely at size 16, based on the length of the hook shank from eye to start of the bend. Again, I looked. It was the hook eye that gave the imitation its oversized appearance. So I dressed some on 18s and they looked just right. Guess which one the fish took most readily? That’s right, the size 18. Many anglers had noted over the years that if the fish doesn’t take the fly that seems to be the right size, then try one a size smaller. However, what I had not understood, and what everyone else had not understood it seems, is that the eye is a very important component of the overall imitation, especially in smaller sizes. Because of the hook eye, a fly dressed on a size 18 looks the same size as a natural that measures a size 16.  So, I no longer measure the hook in the traditional manner, from back of the eye to bend. I now measure them from the front of the eye to the bend.

In addition, a size 16 is not necessarily a size 16. By that I mean that different manufacturers produce hooks that can vary a full size from the “standard” size. One manufacturer’s 16 may be a 17 and another’s a 15. In addition, there are hooks produced that do not specify relative shank length to gap size. For example, what is a “wide gap” hook, exactly? It may have a shank length that is 1X, 2X, even up to 5X short. Then there’s the issue of eye size. A tapered wire eye is smaller than one made without the tapered. So, have a close look at the hooks you are using. Measure them from the front of the eye to the beginning of the bend and make a chart specifying all those dimensions so that you can build your flies on the most effective sized hooks.

A selection of three size 16 hooks, Note variations in gap width and the prominence of the eye. {Photo by Henry Kanemoto