I was as born and raised in St Pete and started diving there in the early 1950s. Most of it was in Tampa Bay where the visibility can be poor. Boats were slow and we didn't have GPS or even depth sounders to find offshore spots. I'm sure there aren't as many fish as in the early 50s, but that's true anywhere. From all I've read the area still offers great spearfishing. The Crystal River Homosassa area would be great. I have faint memories of going up there and the water was much clearer and there was a lot of rock structure closer to shore, but if you have to make a living then that could be a problem.
The diving in Tampa Bay was mainly under bridges. I don't recall knowing of reef areas in the Bay, and my father was a fishing guide so he should have known of them if they were there. But just for old times sake, here is a fish from under Gandy Bridge when I was 14 in 1953. That is a drum, but there were also gag grouper, snook, and Goliath grouper under that bridge. Of course you can't spear snook or Goliath grouper now.
And the other photo is from a couple of years later with grouper, snook, and cobia taken under the Sunshine Skyway.
Edit- Oops, I didn't realize how old this thread was. The OP is probable long gone. Oh well, I got to post a couple ofd pics.