I'm not sure I understand, but WHY even fish for a big fat female while she is on her spawning bed? Sure it's a good chance to catch some of the biggest fish of the season because you have them in a protective mood and pinned down, but these aren't salmon who spawn and die in massive numbers......even if you gently release these fish why stress them when they are providing the stock for the future population passing on her big fat genes?
If it was me I'd just give these fish a break and let em' do their thing......