Is seafood sustianable or is it a con?

I just watched the movie Seaspiracy and it really opened my eyes, as I am sure it did for many others. I normally shop at Whole Foods, and I use their sustainable seafood guide, but this movie just pretty much showed that guide means nothing. So, is there any sustainable seafood out there, or is this just a marketing gimmick like putting an eco-sticker on a Hummer?
I assume that algae is sustainable, and so are some species that reproduce fast, like squid, but it all depends upon how they are caught.
What do you think, is there a sustainable seafood or are 8 billion humans making sustainability an unachievable goal?