Don't know about that. Crabbing has been restricted during certain periods of time to help the population come back. The only restriction I can think of off the top of my head is a ban on soft-shell crabbing during the spawning season, and certain areas of the Chesapeake Bay that are off limits all together.
It's had some positive effects, but we're still a long way off from the glory days of 20-30 years ago.