Fishing is named as an activity in the park material. That is all we have.
The distinction I care about is whether there are species, locations, conditions, and a reason to keep doing it, or whether it is a button you press near water for a fish shaped object. RDR2 had the first. Most games have the second.
Accepted answer
Nothing stated beyond the activity being named. What tilts me toward system rather than minigame is that scuba, kayaking and fishing were all named together, which reads like a water activity category rather than three separate props.
if there are species and they are the right species i will lose a hundred hours to this and never finish the story
A water activity category is a much more useful frame than what I had. If diving and fishing share systems then there is depth there by construction.
Scuba specifically is the tell. You do not build a diving system for a fishing minigame. Diving needs its own traversal, its own camera and its own environment.
There is presumably a lot to find underwater in a state with this much coastline, which is the actual reason to build diving.
Underwater collectibles are the single most Rockstar thing that could possibly be down there and we all know it.