Tricky question..... I suppose you could always say that the yellow tails in many salmon flies herald back to the days of fully dressed patterns with all sorts of rare bits of bird lashed to a hook. As GP is still common it's perhaps reasonable to suggest it's a 'traditional' carry over to many patterns still in use today.
It might be more reasonable to argue that certain trigger colours remain popular and inspire confidence in the fisher so will always be retained in dressings; I know I use yellow a
lot - but then again I'll use pretty much any colour (particularly in salmon flies) if I think it's going to give me an 'edge' if I'm presenting something to the fish that they've not seen before - not so important with fresh run fish, more so with 'residents'.
That's a whole other topic though
To be honest, I hadn't noticed that many streamers in my boxes with yellow in them - but I don't doubt it's true.
H
