Fiddler crab populations in Portugal are decreasing, although not from over-fishing, according to the New Scientist. The fiddler crabs have one extra large claw, which is considered a delicacy by the Portuguese. Instead of killing the crabs, fishermen break off the claws and return the crabs to the water. While the crabs can still feed using their smaller claws, the larger claws attract female crabs and are crucial to the fiddler crab mating rituals. A shortage of fit males for breeding duty has reduced the crab population. Possible controls on claw harvesting are being considered to protect the crabs whose numbers have been declining for two decades.