I saw these little wallet-sized WWF seafood guides for the first time this evening at Kubrick.
In it, popular types of seafood are classified into three categories: "Recommended," "Think Twice," and "Avoid." The category under which each sea creature falls is determined by it's relative abundance in the ocean, and if it is raised in a fish farm (like much seafood these days), by how sustainable and ecologically friendly the farming methods are.
I think this is a great resource to provide to a seafood-crazed city like HK. I never liked seafood much as a kid, but as my tastes broaden, it's nice to know what delicacies get the ecological green light for consumption. Oh, and I was very disappointed to see shrimp in the "Avoid" category. Aside from the rock lobster (who made it onto the "Recommended" list), it looks like all other crustaceans are off limits.