A lot of what I have read indicates UV receptors may be lost quickly when anadromous fish enter freshwater and limited in those that do not go to sea.

I swear there is a difference using UV with dolly varden, salmon, and lake trout. My gut says the debate is still open on rainbows... I have had times when I swore the UV was a killer and other times when non-UV crushed my UV efforts...

And there are so many variables!

Right now eggs are dropping in the salmon streams and the EXACT right bead will catch fish on virtually every cast. Similar but wrong beads will leave you scratching your head... Adding UV colors and sprays (the Spectrum Response in the link) has not been definitive for me...

For lake trout it seems to make a big difference...