Castnetting for shrimp

[Average Fisherman]

I had some good luck shrimping on those jetties near the shore at GI in mid July last year. I didn't catch a single throwback shrimp. Whenever I go to Holly Beach, Little Florida, Deep Bayou, or any of my Cameron Parish haunts, I tend to catch very small bait shrimp. Is this typical? Do the jetties hold nice shrimp, and I'm just benefitting from their close proximity to land at GI? I want to go catch another load this summer, but if it was dumb luck at GI, I'll just go to Holly Beach since it's a couple hours closer. If I need to go the extra couple hours, I'll just roll down in the camper and take a shot. Is mid summer the best time, or is there another season I should shoot for. Thanks for any help. And I don't have a boat, so any tips on spots that need a boat won't help me. Thanks again!