Actually it looks like a small florida Pompano, They have been biting pretty well at the islands, Ship and Cat the last month or so, Did you catch it near the Shipping channel in Gulfport?
I will agree it could be either from the picture, but My guess based on recent fish activity still leans toward the pompano without an upclose look in person...I am basing that on both tail shape and fin placement
The easy way to tell the differance between the Jack and Pompano is the additional forward dorsal on the Jack. The photo does not show the dorsal real well but the black spot on the rear edge of the gill cover is evidence that it is a Crevalle Jack.
