See this thread Best fishing areas for skill-up?
If you want to keep fishing for you own jellyfish in port Bastok, try using Little worms for bait. They are very cheap, but they take up more inventory and the cost does add up after a while. From what I can find, little worms should only target jellyfish and rusty junk. Good news is a rusty item can npc for enough to buy another stack of worms.
Well you could fish carp and sell them on AH. If you got 3k for a stack of moat carp you can buy 5 stacks of jelly fish from an NPC with the profit. See merchant list selling jellyfish
If you are only worried about skilling up to catch yellow globes, don't. They are only level 17. You could catch them now if you want. Sabiki Rig and Halcyon Fishing Rod at Qufim Island (Ice Pond) if your character level is high enough to avoid agro from gobs and banshees. Source: http://www.finalfishing.info/Fish.aspx?fid=26
LoTRO- 62 hunter
WoW- 80 hunter
75 blu/75 war/75 blm
61 rng/54 whm/44 rdm
43 thf/21-37 rest
Nations: Windhurst rank 10, Sandy rank 10, Bastok lol