I don't think you can abandon main quests, though i've never tried abandoning them before. When you complete a quest for the main storyline, the next quest will not become availabe immidiatly. You should go ahead and do some side quests for the time being. You should check the quest log periodicly though, as you will eventually get something telling you to go the harborage.
Is there a way to pick up side quests that were abandoned? I fount the akavari war but abandoned by accident when I was supposed to find the guy that lost his son (forgot his name) and went crazy, using the coral. Thanks in advance for any help