In a way, this game instilled the same sense of dread in me that Dredge did, and it's great for that! When the huge fish shadow appeared under the water and I wasn't able to fish it up, I got out of there ASAP! Brilliant use of tension.
I think, if you were to develop this further, it would be great for there to be a fail state, where maybe your boat gets too damaged from the rocks or the big fish would take chunks out of the boat and make you lose points.
I'd love to see more of this!