What is the fine-grained topic of the following text: Generally, any medium-size Atlantic oyster is called a Blue Point, but Mike Garvey, the general manager, notes that “technically it has to has to spend a certain amount of time in Great South Bay, and most ‘Blue Point’ oysters don’t.” Naturally, he carries the real thing, from just off Fire Island, plus ones that live in the Oyster Ponds, out near Orient Point on the North Fork. Only return the topic.
"Blue Point Oysters and Their Authenticity"