I've completed 'Deadliest Catch'. It's really short for a master quest. The story is missing some depth too imo. For the rest it was a pretty cool quest. I especially love the sailing part. :p
I hunted the monster down 10 times and got all the hunter xp. I think after you catch the last one, you talk to Jones and in the second or third chat box there's a typo. lol.
I didn't hunt the monster down 10 times, no, as I want to save it for when I want to do it again. And about the completionist cape, nothing of that matters to me as I have sworn never to max total.