I have full Foragers gear and max melded in perception and gathering. With food and FC buff, I hit around 410 gathering.

I am still having fish at 310~ gathering get awya due to just RNG.

Gathering only makes it so you can catch the fish, nothing else at all.

This isn't just speculation, this is just through and through how it is. When I have the current maximum gathering you can aquire, you'd think that I should be able to catch 1 stars and 2 stars with no misses, right?

Wrong. They still get away now and then.

EDIT: Though I will test this out when I get the Ironworks rod. Apart from that, I'm maxed.