Fishing on the go

For sure!
Yes/Definitely!
Positively!!

This really depends on where you are fishing and what the local regulations are. In the US, you need a fishing license issued by the state you are fishing in. Some places restrict where you can fish. And most places have restrictions on what you can keep or size restrictions. So you really need to check the regs wherever you plan to fish. Where I am we have a crazy amount of regs that change all the time. It can be confusing but if you violate a reg and get caught the fines are substantial.
We can catch, lean and cook some fish right away but again, the regs determine what you can do. We are limited on this according to the type of fish.
Our regs are even more challenging as most of the fish around us are state regulated but then our Halibut is Federal regulated. So Fish & Game and State Troopers regulate salmon, rock fish, fresh water stuff, etc and then USCG and NOAA enforce halibut.

In addition to the above advice regarding state permits and federal pelagic fish permits. Yes we often fish while island hopping for tuna wahoo mahi-mahi. Early in the morning or early evening as sun sets is a must and need to fish the drop off. You can tow lures in open deep water or in the middle of the afternoon but won’t catch much

Or better yet, write about something he actually knows about. Isn't that the first suggestion to writers?

I think the internet has pretty much killed that concept.

Especially with the advent of affiliate marketing blogs. You can't find any good information anymore when you're trying to look up something now that the internet is full of barely plausible word salads wrapped around Amazon links.