AFAIK - Most prawns/shrimp that are bought at the markets and restaurants here are farmed. They have never been near the sea. Same goes for frozen shrimp/prawns - even seabass (most mussels, scallops, and other shellfish too).
In my area (Sattahip) squid is the only seafood I know that is locally fished from the sea and available in local markets/restaurants. I see the Bang Saray squidboats going out to sea most evenings with their green/white lights dotted across the night horizon.