Looks very well done. Professional in anyones definition, but yea, I've seen those cover competitions. Pretty tough
They do lean more towards traditional painting methods (as well as artist that are more known for marine life "paintings" in around the Florida fishing scene. I think the Mag wants that connection for the readers to be able to recognize an artist name or style from their area.
I live here in Central Fl. When you look at all of the candidates, they all seem to be "from" and participate in and around those scenes. You will see them at events and what not. The artist street shows and fishing shows etc.
One of our printer members here had been recently looking for some art like that to use for a fishing tourney for his family member. I think it was for a small sublimation order but you could sell him a use of that. Contact Matt aka balloonguy (member here).
Nothing wrong with yours tho. Great job!