I fish for 3 month straight to get all the resources and did the quest. few of us done it the get the new monster, ( glass and bait) after we have kills enough to get a full suit, we quite since it was pointless. Now my 120 skill it use to gather ASOS. For me 100 or 120, have no impact on fishing.
If you are looking to enjoy the high seas pack do the quest but it will take alot of your time (lots of fishing and crabing can be scripted but their is not a public script for doing the quests) to get to 120. If you are impatient and what to get the 120 and get onto something else you prefer doing go ahead and buy the 120.
Masscre is correct, you will need do this by manually, long and boring or write your own.