200 DESCRIPTION OF IMPORTANT FISHERIES AND THEIR PRODUCTS 



can frequently develops from the interaction of the copper pigments 

 (hemocyanin) in the crab blood with the ammonia and sulfur compounds 

 formed from the breakdown of part of the protein during heat processing. 

 A patented process^" minimizes the discoloration, improves the product 

 quality, and forms the basis for the canning of blue crabs in the Chesapeake 

 area. Citric acid is used to adjust the pH of the meat on the acid side to 

 minimize the discoloration reaction. Either aluminum or zinc sulfate 

 (not over 0.04 per cent) is added for further protection against formation 

 of colored complex salts. 



The inspected meat is dipped in one per cent brine with the above 

 additives, drained, and filled into C-enamel (seafood formula) cans. The 

 cans are vacuum sealed by use of an exhaust box or vacuum closing 

 machine and in common practice are retorted 30 minutes at 250°F for 

 a 63-^ ounce can. As in the case of processing other crabs, it is essential 

 in handling blue crab meat that all catalytic metals such as iron and 

 copper be eliminated from the production line, preferably by substitu- 

 tion of stainless steel or other noncorrosive materials. 



Dungeness Crab. The Dungeness crab (Cancer magister) is distributed 

 from the coastal waters of northern California northward along the 

 Pacific coast to the central coast of Alaska. Generally, the season in 

 Washington, Oregon, and California is early winter to late spring. In 

 Alaska the different timing of the molting cycle provides a season from 

 late spring to fall. 



Fishery Methods. The Dungeness crab is much larger than the blue 

 crab, usually weighing from two to three pounds, and it has a carapace 

 width of from eight to nine inches. It is caught almost entirely in circu- 

 lar-type metal pots designed for stability in use on the open ocean bottom. 

 Some rectangular pots are used, also ring nets in some locations where 

 there is little current action. No other type of gear is legalized by the 

 Pacific Coast states. 



The circular pot is about 42 inches in diameter and 14 inches deep 

 and has two entrance tunnels. A metal or plastic container is hung inside 

 the pot with bait of clams or fish heads. After the fisherman hauls up 

 each pot, he empties it, sorts the crab rapidly, and rebaits the pot ready 

 for use. Legal males in good condition are placed in the live well in circu- 

 lating sea water. Boats fishing close to the plant may simply store the 

 crabs in boxes on deck. 



At the dock, either the crabs can be held for a few days in the vessel's 

 well or they are transferred to live floats off the dock or to live tanks on 

 the dock. In some areas the pollution of harbor water makes it unwise 

 to leave live crabs in dock floats or tanks, and it is necessary to use a 

 storage float in unpolluted water some distance from the plant. 



