Under experimental conditions, but using commercially accepted techniques, 47% of stone crabs that had both claws removed died after declawing, and 28% of single claw amputees died; 76% of the casualties died within 24 hours of declawing. The claws constituted 51% of the total weight of the crabs before declawing.[8] In the wild, where declawed crabs must compete for food, mates, and shelter, and avoid predators, the mortality rate is likely to be higher. Declawed crabs survive by switching from predation to scavenging.[9] The occurrence of regenerated claws in the fishery harvest is low, with studies calculating from less than 10% (1978),[8] 13% (2006),[7] to 20% (2010).[10] Larger, older crabs generally do not survive long enough to regrow their claws, as they are near the end of their lifespan.
There is a famous (world famous) resteraunt in Chicago that is renouned for its crab claws imported from the Gulf every day (well maybe weekly) and very good they are, although ours are better.
Of course they claim it is crab friendly - I did wonder at the time whether it was jsut a good marketing gimmick - now I know.
I recall disembarking from the Oban->Castlebay ferry late one evening as foot passengers with our sea kayaks (this would be about 30 years ago) and through the crystal-clear water from the pier you could see that the sea bed comprised nothing but de-clawed dead crab bodies as far out as you could throw. Yuk.