Yes there is Lombards (sp?) at the main Universal park, its really nice, on kind of a dock over the pond, similar to a seafood restaurant you would find in a harbor or something. Its a nice sit down seafood restaurant.
Bubba gumps is a seafood place, but I've heard it has had mixed reviews, and I've never been to that one myself, I've heard its much more casual, lots of fried food, which I don't do fried seafood.
Several of the restaurants have plenty of seafood on the menu as well. Mythos has had some GREAT scallops, last one I did was their risotto for the day or something. And I'm going off memory but I'm pretty sure both Emerils restaurants have some seafood on the menu, but not 100% sure. I know I'm missing quite a few things as well, I know several of the other restaurants, particularly in the hotels have seafood on the menu. I want to say that Jake's American bar even has some seafood on the menu, that's a great place IMO too. And it seems like I'm missing another seafood restaurant outright.