Ray, I can't explain what that white thread is. Here is a closer look:
And Mike, you make a good point about the difficulty of setting a hook with such a huge barb. This is what Leisenring said about the problem:
The overlarge barb is one of the serious causes of losing fish. Often you may hook a nice trout, play him a while, and then suddenly find the fly coming toward you and the fish going in the other direction. Eight times out of ten, I assure you, the barb of your hook was not deep enough into the fish’s flesh. You simply had the point of the hook stuck into him up to the barb. As long as there was a fair amount of tension on your line it held him, but as soon as he got slack line he was able to eject the fly. Any hook that is set over the barb into that gristle or tough flesh is not going to be dislodged very quickly by any trout, even if he does manage to get slack line. Most hooks sold today have a barb so wickedly big that, even if you do manage to set it into a fish’s jaw without breaking your gut leader, the barb makes such an enormous gash or hole when it enters that it becomes as easily dislodged as a hook which has not penetrated over the barb.
