Call a few of the higher end sushi restaurants. Most have uni nigiri or sashimi (which should be local at this time of the year), some should have live uni. I'd think Blue Water cafe in gastown would also have local uni as well.
The better sushi bars typically have live uni at this time of year (good timing for your visit). We had some delicious uni at Kimura last night, though he did mention he was shorted on his order, so perhaps he is not getting it locally.