Blue crabs proved more difficult to mark successfully than lob- 

 sters. Injections were made in the ventral surface of the swimming leg, at 

 the articulation of the coxa and basis. This often produced a very faint, tem- 

 porary discoloration which could be seen externally overall. Most of the 

 crabs molted at least once during the holding period. When killed after 40 

 days, the crabs marked with fast green FCF had a distinct green color in 

 the gill filaments. Those marked with Trypan blue had a fair blue color in 

 the gill filaments, suggesting that they were administered an inadequate 

 amount of stain. The results indicate that to insure optimum marking and 

 survival particular attention should be given to the amount of stain selected 

 in respect to individual crab weight. 



A marking technique is most useful if a marked animal can be 

 readily recognized at the time of recapture. Since the exoskeleton of both 

 spiny lobsters and blue crabs is opaque, marked individuals would not nor- 

 mally be noted when first captured. As the Florida spiny lobster industry 

 is now conducted, recovery of marked individuals together with the neces- 

 sary biological information would present a problem. Spiny lobsters nnay 

 be marketed as whole animals either live or dead. Therefore, the gills are 

 not normally exposed until the lobster reaches the consumer. Spiny lobsters 

 may also be sold as "tails, " in which case the entire cephalothorax is re- 

 moved by the producer. The gills of an intact lobster, however, either alive 

 or dead, can be examined for stain by lifting the carapace with needle -nose 

 pliers. The stain injection technique of nnarking spiny lobsters would prob- 

 ably be limited to studying local populations, where captures could be exam- 

 ined by trained observers. 



There are several methods of marketing blue crabs. Soft-shell 

 crabs and large male crabs are marketed alive. Consequently, they are 

 generally in the hands of the consumer when the carapace is removed. The 

 great majority of blue crabs, however, are utilized in the production of 

 picked crab meat. In this process, blue crabs are cooked, the carapace 

 removed, and the meat picked, usually in a plant near the area of capture. 

 The stained gill filaments do not fade with cooking so there is a good op- 

 portunity to recover marked individuals, together with the desired biolog- 

 ical information. 



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