Ginger is good for nausea. But of course, with moderation. Too much can cause uterine contraction, same as unripe papaya, and pineapple.
Fish.. the issue is with the mercury level, so as NDDomer mentioned, king mackerel, swordfish, tilefish, shark, etc should be avoided... And the issue about sushi is that it may not have been handle correctly, and may have parasites or viruses.
Don't know about abalone, shrimp or crab...