CRAB AND LOBSTER FISHERIES 195 



ation in crabs and lobsters. These natural anatomical divisions control 

 the amount, yield, and edible characteristics of the individual meat 

 sections. 



Respiration and Circulation. In crabs and lobsters, as in most Crustacea, 

 the oxygen-carrying pigment in the blood is a copper hemocyanin rather 

 than an iron hemocyanin. The blood is relatively colorless but leads to 

 objectionable discoloration in processing because of the facility with 

 which the copper compound forms light blue to blue-black complexes. 

 A related feature in the circulation of crabs and lobsters is the absence 

 (or vagueness) of blood vessels in the peripheral areas. The blood circu- 

 lates in sinuses of poorly defined structure. Part of the problem in holding 

 crabs in good condition before processing lies in the general perfusion 

 of the tissues with the blood and the difficulty of bleeding the animal 

 before death. Some of these problems and possible solutions in processing 

 Dungeness crab {Cancer magister) have been discussed by Farber^ and 

 Elliot and Harvey^ 



Live-holding Requirements. In earlier years of the Pacific crab fishery, 

 the fishermen and processors often held the crabs out of water. Processors 

 recognized that when the crabs died before butchering, adverse quality 

 changes took place. Even if the crabs were still (but barely) alive when 

 butchered, discoloration, chalky texture, and poor keeping quality of the 

 meat were frequently a result. Recognition of the need for maintaining 

 the crabs in a vigorous healthy condition until butchering has brought 

 general acceptance of live wells for holding the crabs in circulating sea 

 water on the vessel and ashore prior to processing. 



Holding pounds have been used in the lobster fishery of Maine for 

 more than 60 years^ and provide facilities for long holding or condi- 

 tioning periods in order that lobsters can be marketed to the best advan- 

 tage. Blue crabs ready to molt are commonly held in floats in order that 

 the soft-shell crab can be harvested after the molt. 



Preliminary Process Requirements. In contrast to shrimps, crabs and 

 lobsters must be given a water or steam precook to firm the meat and 

 to allow ease of removal from the shell. If raw crabs or lobsters are 

 frozen, the meat is most difficult to remove from the shell after being 

 thawed and cooked. Indeed, the meat appears to be glued to the shell. 

 In some instances a minimum precook or blanch has been tried ; however, 

 a complete cook is almost invariably used for marketing the crab in the 

 shell or for subsequent meat processing. Although the obvious changes in 

 crab meat during cooking suggest that the meat shrinks in weight, loses 

 water, and increases in total solids content, recent studies on composition 

 of raw and Dungeness crab indicate no marked change in composition 

 resulting from cooking. 



