Since most sushi selections feature different types of raw fish, then it would be easier to ask if it is raw.
Point to the menu or display and ask:
"Nama desu ka?"
If he replies with a, "Hai," then you will probably want to follow up with the statement:
"Nama wa chotto..."
and let the sentence trail off with a slightly embarrassed expression.
That way you let the sushi chef know that you're looking for cooked sushi (such as shrimp, eggs, etc.).
What will follow will probably be a whole lot of pointing, but at least your chef will know what to suggest and what not to suggest.