So, I've decided to not look into this at all, but my understanding is that you're scored by like, size and weight of the best fish or added up fish total by the end of some fishing time limit. So like...isn't this mostly up to the fish? This meta feels VERY rng driven and hardly suitable to competitive play. 
, but it came to kind and I'm curious how the fuck anyone gets credit here. If anything it should be whoever can catch any fish first.
Different size fish hang out in somewhat different parts of the lake, and eat different things. You can use a physically larger lure to prevent yourself from catching small fish (but might catch nothing). Knowing what fish are biting when and where for the given time of year and day and weather is a skill.
But honestly I think it's mostly cheating.