Dolphin are a very sustainable fishery. From what I can find, spawning occurs year round in the southeast US waters, with some variation as you get further north. Peak spawning season is January through July. Males reach 50% maturity at 476 mm Fork Length (18.7 inches) and full maturity at 645 mm FL (25.4 inches). Females mature at a smaller size, with 50% at 458 mm FL (18 inches) and 100% at 560 mm FL (22 inches). I personally would not take immature fish, which seems to be less than 18 to 25 inches. I would probably opt to keep those over 25 inches. Anglers sometimes have to be willing to help keep a species sustainable by setting their own limits.