Personally, even before I was vegan I could never stomach that type of food (the consistently of an oyster - eugh!) so it's not something I'll be taking up any time soon, but I am very interested in the ethics of it. A snippet of what Singer had to say on the topic:
"I've gone back and forth on this over the years," he said. "Perhaps there is a scintilla more doubt about whether oysters can feel pain than there is about plants, but I'd see it as extremely improbable. So while you could give them the benefit of the doubt, you could also say that unless some new evidence of a capacity for pain emerges, the doubt is so slight that there is no good reason for avoiding eating sustainably produced oysters." - Peter Singer
Two articles/resources on the subject:
http://www.slate.com/id/2248998/ - "Consider the Oyster"
http://letthemeatmeat.com/post/506197250/did-oysters-just-kill-veganism - "Did Oysters Just Kill Veganism"
I don't think I agree with a lot of the content of this article, which seems to take a very negative view of veganism (which I see as a positive thing!). However it also examines some comments by vegans that were responses to the above article, and this I found illuminating because it covered a lot of the arguments I came up with against eating oysters. One quote from a commenter I found particularly pertinent:
"I have to have a legitimate reason for everything I exclude from my diet ... I would be cheating my standards if I left oysters off the menu just because I’m supposed to, and not because I think it’s a good idea." - brosephstalin33
I definitely agree it’s somewhat silly to say "I won't eat oysters because then I wouldn't be vegan", (which seems to be the argument of many commenter’s), because personally I base the choices I make on what I feel is ethically correct, not on what I want people to define me as. Of course this argument only applies if that’s the only issue with eating oysters – which I am not 100% convinced about yet.
Some others argued that eating oysters was “exploiting” them, which is against a vegan lifestyle, but I don’t see why with this argument isn’t then applied to plants – we’re exploiting them for their products to, and if I don’t have a problem with ‘exploiting’ plants, and oysters are essentially plants (for the intents and purpose of this argument) well then I wouldn’t have a problem with “exploiting” them either.
Anyway I've seen some other discussions on this topic get pretty heated, and I want to stress that I'm not trying to make a real argument for it either way (at least not yet) - it's just an issue that really interests me and I would love to hear some other vegan opinions! Not trying to start a fight, just hopefully a discussion!
Oh, also, one last thing, if anyone knows of any articles or studies or whatnot (preferably scientific/scholarly ones!) about studies on bivalves in regards to these issues, I would love to know about them!