Fishing quests not being removed from your quest log are caused by turning in multiple fishing quests at once. Say you are turning in two fishing quests to the same destination. You talk to the fish monger and he gives you both rewards and the quest complete dialog. It will them remove one quest. If you talk to him again he will give you the quest complete dialog again before he will return to normal dialog. However the second quest entry will not be removed from the quest list and the monger who gave it to you will respond, "I have nothing for you at this time." until you cancel it. If you ever hear this phrase when double clicking on a fish monger then you have a bugged quest entry. Does this cancel after completetion cause standing loss? Don't know. No way to test. Until the DEVs fix this the only solution is to only make sure only one crate is full. Turn in the one quest. Hop back on the boat fill the second one. Then turn in the second. I have not tested with more than 2. tl/dr. Do not turn in two quests at a time or it will not remove the second quest entry.