The funny part is, I don't remember ever going fishing with my granddad. I remember fishing with my nana, half the family draped listlessly around a dock accidentally catching blue crabs and flip flops. And I remember going scalloping with my aunt and uncle and cousins, pointing out the scallops from the safety of my little boat tied to the side of the bigger one while my cousins dove for them.
It's hard to tell what the dates of these maps might be. On them, the Courtney Campbell Causeway is still called the Davis Causeway, which suggests that they're from sometime between when the bridge was built in 1934 and when it was renamed in 1948. One of them has the Gandy Bridge, which was opened in 1924, and it looks like it only has the one span, which was on its own until 1956. None of them have the Howard Frankland, which opened in 1959.
So maybe the maps of Old Tampa Bay are from somewhere between 1934 and 1948. (The maps of Crystal River and the Withlacoochee and other places inland and up are even harder to figure out.) But if you're making maps for fishermen, they don't much care what the bridges are called, just that they're there. So they might have kept printing them until at least 1956, and maybe as a novelty after. My granddad was born around 1935, so if they're from the early end of the spectrum they almost certainly didn't originally belong to him. It's all something of a mystery.
Ultimately, of course, the when of them doesn't matter. That they were his is the important part, and that they show a side of where we're from that was gone by the time I was there.