Such a fining system would be extremely abusable, and any system that could make it more balanced would be an utter pain to implement.
I also want to point out something regarding your suggestion, earlier, that the fine would be paid on the destruction of the offending ship, if he does not pay. Well what if he gets away, but is then killed later? I doubt you could "shut off" the fine after leaving the proximity of the fining ship, without some painfully difficult coding. In that case, the random death of a pirate could cost said pirate millions and millions in unpaid fines, even if they've already been successfully evaded.