With fishing contest also including fishes that can only be obtained by harpoon fishing, maybe now is the time to update/rework harpoon fishing.

1.) Remove big ship restriction: Why is harpoon fishing limited to only small boats is still beyond me. It's time to allow harpoing on carracks also.

2.) Mastery over 1200 currently have no benefits for harpoon fishing, and it would be nice if we could have higher chances of obtaining better fishes with higher mastery

3.) Add Manos Harpoon with higher durability and additional damage, so it required less hits to catch the fish

4.) Add something like triple-float, for chance of catching 1-4 fishes at once while harpoon fishing

5.) Increase price/value of fishes obtained by harpoon fishing: It's not afk activity so it should bring decent money.

I don't think any of those idea are hard to implement.

just remove harpooning and dump the harpoon fish into the regular fish tables.

I'd be happy with Pickenose's or Simon's idea. I totally forgot about harpoon fishing and I cruise all the way out to the middle of the ocean and learned the boat I was on would work and neither would a fishing pole. I'll just stick to the contest fish you get with a rod until/if it gets changed.

Now that would be even easier to do ^^

And it would be perfectly fine to most of us. Not sure that there are any players who actually enjoys harpoon fishing as it is.

I agree with #1, would be nice to use harpoon on any ship.

Another thing is, when you catch a fish there is a long animation of a wriggling fish on the screen, followed by a several second pause before you can collect the fish and recast.  It would be amazing if we could skip that animation somehow, it's the most frustrating part of harpoon fishing in my opinion.

the least they could do is remove rod catchable green and blue fish from loot table, harpoon fishing should be on par with hot spots where it's all yellow fish

Also: it takes 10 hits to take down a fish with a harpoon, even when you don't miss a single shot. Maybe the number of hits should be based on the size of the fish and the quality of the harpoon you're using, but it shouldn't take more than 5 hits, that's enough to prove the point. Any more feels pointless and boring, doing the same thing over and over again.

And why can't we have a fixed, opaque UI overlay (e.g. like Royal Workshops) ... it's shaking and moving with the cursor and the waves on the boat, swinging between the ocean floor, the inside of my boat and the sky, making it hard to spot the fish and aim in some situations - maybe even causing motion sickness. 

Also, there's a bug where if you open the knowledge screen, it's even worse.  The camera goes haywire while you're harpooning and you have to restart the game to fix it.

But to your first point, I agree.  Grade of harpoon, maybe fishing level or mastery should reduce the number of hits it takes.

And while you're at it, fix that issue where you don't get the minigame to pop,
OR give a clear indicator of where harpoon hotspots are, like the seagulls, should it not be a bug that makes moving 1 step gets your chance to catch fish using the harpoon to 0% even over several hours.