Crab were tagged internally using an automated microwire tagging system (NMT) designed for field use. One CWT measuring 1.5 mm x 0.25 mm was injected via a 24-guage hypodermic needle into the basal muscle of either the right or left fifth pereiopod (backfin) of each crab. Although binary coded tag were used in our experiment, the binary code per se had no relevance to our investigation.