208 MARINE FISHERIES OF NORTH CAROLINA 



the bottom, which it inhabits throughout the rest of its life. Thereafter the 

 young crab molts or sheds its shell about 1 5 times before reaching maturity. 



Crabs, being confined in rigid shells, do not grow at a steady rate of increase 

 in size but only by a series of quick expansions mostly within an hour or 

 two while in the soft state at each of these molts. After the shell hardens 

 each time, it remains of constant size until the next molt, but of course the 

 crab inside increases in weight. Most crabs attain their full growth and 

 mate during their second summer, when from 12 to 14 months of age. 



Young crabs, hatched near the sea, begin a movement up the sounds and 

 rivers into brackish waters. Cold weather in the first winter interrupts this 

 journey, and the young crabs settle to the bottom to remain dormant until 

 conditions become more favorable. In the spring movements are resumed 

 and growth proceeds rapidly until they reach maturity in summer or early 

 fall. The female crab is fertilized during this last molt or growth stage and 

 subsequently tends to move from brackish water to more saline areas nearer 

 the ocean. The adult male usually remains behind. In the following spring 

 the females move out of the deeper waters where they have passed the 

 winter and seek shallow inshore areas to spawn. Most female crabs reach 

 their life span after the end of the first spawning and die when from 2 to 3 

 years old. While the first spawning is known to occur in the third summer 

 in Chesapeake Bay, it is possible, in a milder temperature, that spawning 

 may occur as early as the second summer in more southern regions. A sig- 

 nificant feature in the life of the blue crab is the fact that this crustacean, 

 like the shrimp, is a short-lived creature, seldom living more than two full 

 years. Blue crabs are available to any fishery only during the last half of 

 their customary two-year life cycle. ^ 



FISHERY 



TYPES OF CRABS 



Both adult and immature crabs are taken in the commercial crab fisheries 

 of North Carolina. Adult crabs provide the major source of hard crabs and 

 are sold alive by weight or volume to processing or picking houses at the 

 end of each day's fishing. Adult crabs average 3 to 4 individuals to the 

 pound and are generally marketed in 100-pound barrels. From 10 to 15 

 pounds of edible crab meat may be extracted from 100 pounds of crabs — 

 the amount varying with the skill of the picker and on the size, sex, and 

 physical condition of the crab. Male hard crabs are most sought after 

 because of their higher yield of meat. Crabs, soon after molting, are known 



2. Additional information on the details of the life history of blue crab will be found in Hay 

 (1905) and Churchill (1919) and, on the zoological classification of the crabs, shrimps, etc., in 

 Hay and Shore (1918). 



