1. 3 Rock Crab, Cancer irroratus and Jonah Crab. Cancer boreal is 



The rock crab, Cancer irroratus . occupies continental shelf 

 and slope waters from Labrador to South Carolina, but may occur 

 southward to Florida. In northern areas the crabs are found in 

 shallow coastal waters where they may be found at all seasons, 

 while in mid-Atlantic regions they may move inshore to molt 

 during winter and then return to deeper waters. In the Middle 

 Atlantic Bight the highest density of rock crabs occurs at 

 40-60 m during summer months (Bigford, 1979) . Water temperature 

 has an important role in the distribution of rock crabs in both 

 inshore and offshore habitats. Haefner (1976) found rock crabs 

 at depths up to 335 m in continental shelf slope waters, and at 

 depths ranging to 296 m in the Norfolk Canyon. The crabs are 

 virtually absent in shallow bays of Virginia, Maryland, Delaware, 

 New Jersey, and New York during summer months, but remain in bays 

 from Massachusetts to Canada throughout the year. 



Jonah crabs. Cancer borealis . have been found from 

 Newfoundland to Florida and in the Bahamas (Haefner, 1977). They 

 are most abundant off New England and the Middle Atlantic States 

 at depths of 12-300 m. Landing statistics on Cancer crabs 

 include both C. irroratus and C. borealis . Commercial catches 

 from inshore waters (Delaware to Connecticut) varied erratically 

 during the decade 1978 to 1987 from 100,000 to 400,000 pounds (45 

 to 180 metric tons) . Offshore landings for the same period ranged 

 from 300,000 to 390,000 pounds (135 to 175 metric tons). Thus, 

 Cancer crabs support a small but commercially valuable fishery. 



1. 4 Blue Crab, Callinectes sapidus 



The blue crab supports a valuable fishery along the mid- 

 Atlantic coast and Gulf of Mexico from Cape Cod to Texas. Waters 

 of the Chesapeake Bay and the Louisiana coast produce about 65% 

 of the commercial catch by weight. The blue crab fishery ranked 

 second in volume and fifth in value among all United States 

 crustacean fisheries in 1987. Fishing activities are intense 

 during the summer months but a significant fishery for dredged 

 hibernating crabs takes place from Virginia to New Jersey during 

 winter. Although blue crabs do not represent a major fishery in 

 the New York Bight or New England, studies on shell disease in 

 this species may lead to a better understanding of the onset and 

 progress of this disease in other crustaceans. Furthermore, blue 

 crabs are year-round residents of coastal rivers and bays, often 

 in areas of sewage and industrial outfalls where contaminant 

 concentrations are higher than in near- and off-shore waters. 

 Many of the microorganisms identified from diseased shells and 

 gills were isolated from blue crabs, and provided much of the 

 groundwork for similar studies with other crustacean species. 



