At least locally there's a shortage. Usually the season opens in time to get some crab for Thanksgiving, and it stays open until February.
During the season, you can simply go to the harbor, and on at least two different docks, you can walk right in, pick your own crab that's swimming in the tank, and take it home for dinner.
On the grand scale of things, I don't think it's going to lead to a national shortage...after watching "Deadliest Catch", I think the Alaskans have a big portion of the crabmeat industry.