More and more places on the West coast seem to be offering soft shell crab these days. Most recently seen at an airport restaurant at STS.

a) I don't think it is moulting season.
b) I don't think this is a West coast dish (though crab itself clearly is).

I've always wanted to try one, but I'm deeply suspicious of the authenticity of late season West coast soft shell.

Where are these crabs coming from?