Sam, right on. My college sweetheart and I used to go out to Tierra Verde, near Sunshine Skyway and do it just like that. We would easily fill up a 5 gal bucket in an afternoon, and sometimes 2 buckets on a good tide.
A few long sticks stuck down into the bottom in around waste deep water with the string and chicken neck (or back). When a stick would twitch, we'd go to that one and slowly reel in the chicken piece and slide a net under the crab. Works like a champ.
Sometimes I'd net some tilapia off the seawalls on the way home.
Good eats, and free.
