The northern seas have the Majadan and the Xiadan nations controlling it, and likely the main two nations about to go to war. Because of their constant warfare there isn’t much of a sea population there, but plenty of sea monsters and sunken ships awaiting plunder. It’s not unusual for scavenger crews to operate in those waters, and they’re well known for their abilities in amphibious combat.

Pirates turning in bounties in other pirates isn’t unusual, just impracticality difficult for those with any bounty to their names. A criminal taking another criminal to a fortified guard facility to collect on a bounty is just asking for two bounties being captured. Regular Bounty hunters aren’t really considered raiders either, since people putting a bounty on your head for your pirate activities is just part of the job, and thus dealing with bounty hunters is the same as dealing with a guard escort. Mind you, betraying your fellow pirates to collect their bounty is still a dick move. I’d say, Tayang KO’s you and turns you into the guard for your 2k bounty, Tayang will need to make sure he never goes into the sea again or else anyone who heard about how he betrayed you will do terrible, Terrible things to him.

Incidentally, the Ransom Brokers who buy slaves can also be used to turn in pirate bounties, at a price or course. They’re the middleman who’ll effective give you a cut of the advance pay on the bounty, and then they’ll later go and formally collect the bounty themselves. This is the “normal” way for pirates to turn in bounties in each other, what with their own criminal nature making conversing with honest guards difficult.

Theresa can act as your go-to thieves guild rep. She can help facilitate the hiring of an official thieves guild member, who depending on what you’re willing to pay could be anything from just a bandit with thieves tool prof or someone of greater skill like a spy. Alternatively if you’re looking for someone with actual class levels, that will require you to actually go out of your way to find the right person. Still, Theresa could point you in the right direction.