Commercial catches of red crab reported in 1973 ranged up to 

 3,500 pounds (1600 kg) per towing hour (Meade & Gray, 1973) showed 

 that the fishery was small but of significant market value. The 

 impact of shell disease on the marketability of commercial catches 

 has not been determined. Commercial fishermen, however, have 

 voiced concern over the visible appearance of shell diseased 

 individuals and its effect on market value. 



The golden crab Geryon fenneri, although not found in the New 

 York Bight apex, is also affected by shell disease. Wenner et al, 

 1987, examined 3,183 specimens from the South Atlantic Bight and 

 found that 95% had blackened abraded areas on the exoskeleton. 

 Damage to the exoskeleton was noted in 19% of the premolt crabs, 

 and in 75% of those in intermolt. One or more appendages were 

 missing from 2.4%, and pereopods were missing from 9.6% of the 

 specimens. 



2 . 3 Shell Disease in Rock Crabs and Jonah Crabs 



Molting behavior, male: female ratios, carapace width, and 

 geographical distribution have been found to influence surveys on 

 the prevalence of shell disease in rock crabs, C. irroratus 

 (Table 4). Shell disease in nearshore waters of New York and New 

 Jersey was found to occur in <5% of the specimens examined during 

 molting periods, but up to 20% during intermolt periods (Fig. 6). 

 Other studies at the now closed Philadelphia-Camden sewage sludge 

 disposal site 40 miles offshore, showed that shell disease was 

 present in 16% (91/580) of the specimens examined during 

 intermolt periods, and in 8% (33/426) of a second group when 102 

 of them had undergone a recent molt. Data from the New York 

 Bight apex showed that inshore females mated in late fall 

 followed by shoreward migration and molting of males in shallow 

 rivers and bays. Mating periods showed a male: female ratio of 

 approximately 1M:1F, while post-mating and subsequent molting by 

 males showed a ratio of up to 100M:1F. In the deeper offshore 

 waters newly molted females and males often were captured at the 

 same time and ratios rarely exceeded 5M:1F. 



The prevalence of shell disease among offshore decapod 

 crustaceans from clean or unimpacted habitats has not been 

 studied extensively. The lack of such data is due to the fact 

 that very few, if any, coastal environments from Canada to 

 Florida have been completely spared the effects of pollution. 

 Studies on rock crabs and lobsters in the New York Bight apex 

 have shown that when migratory behavior, molt cycles, and sewage 

 polluted sediments are taken into account, prevalences of up to 

 20-30% in intermolt specimens are not unusual. Prevalences of 5- 

 6% or less, in locations where contaminant levels are low, 

 suggest that this range may be "expected" while the higher 

 figures represent levels of disease that may be superimposed as a 

 consequence of contaminant inputs and sea bottom degradation. 



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