The standard answer for seafood in Portland has always been the over 100 year old Jakes on SW12th. It can be crowded, noisy but fun with a very big menu. Most tourists will make a stop there. I still like their chowder.
Some new entries you might try are: The Farm Cafe on SE 7th and Seasons & Regions on SW Capitol Hwy. A new place that opened recently that I have not tried is Bay 13 on NW 12th. I've heard it was expensive and needs to work out the opening kinks.
There are many Vegetarian and Vegan options here.
If you want some suggestions in that arena, just ask.
re: Sir EatsAlot
I'm not a big fan of Jake's, and that might be a bias against places that are, as you mentioned, touristy. While it's based in Portland, it is part of a large chain of restaurants, and most of the people there seem to be from out of town. If you do go there, stick to the simpler fish/seafood items, because they do OK with those.
I'd recommend the Alberta Street Oyster Bar and Grill for a smaller place where most of the dineres are local. They have several non-meat items on the menu. Marco Shaw of Fife is also supposed to be opening a seafood restaurant--does anyone know when that will be open? I'm afraid that it won't be until after your visit.
Even with Shaw's new seafood restaurant not being open, a visit to Fife Restaurant is an amazing chowhound experience and he always has a number of seafood appetizers as well as at least one seafood entree on his menu at all times. Be sure to sit at the chef's counter as you are a mere 2 feet away from the action and can interact with all of the chefs, see the meals as they leave the kitchen, and enjoy the fun banter and conversation from their talented staff. I eat at Fife at least 4 times a month - I love it!
Alberta St Oyster Bar, Carlyle, and Southpark all have more fish dishes than the norm and do a good job, especially the first two.
Jake's has way more choices and it has a classic feel, but beyond the fish itself (ie, the sauces, the sides) the place isn't all that good.
Most restaurants in Portland, though, have a veggie and fish entree, often more than one. And there will be even more options in the appetizer section beyond just salads. This is a very veggie-friendly city. So you're often fine just choosing what sounds like the best restaurant, especially this time of year when the produce abounds. Look at Wildwood's current menu, eg:
Two fish entrees, one veggie. Five more veggie items under apps and three more seafood items.