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Fishery Bulletin 102(4) 



that bay all year (Reilly and Saila, 1978). In contrast, 

 in Delaware Bay and Chesapeake Bay they occur in 

 coastal waters and estuaries mainly in colder months 

 (Winget et al., 1974; Haefner and Van Engel, 1975; 

 Haefner, 1976). Our data showed that rock crabs in 

 the Hudson-Raritan Estuary conform to the pattern of 

 migration typical of the latter southern bays. 



A crossroads or overlap in distribution of the three 

 crab species is more evident when a broader area on the 

 continental shelf from Cape Cod to Cape Hatteras is con- 

 sidered. Crab presence was plotted by using data from 

 the fall 1992 continental shelf trawl survey <Fig. 11). 

 Fall surveys are done in September and October when 

 waters are still warm. In the coastal waters off Rari- 

 tan, Delaware, and Chesapeake Bays, blue and lady 

 crabs were collected, whereas rock crabs were collected 

 mainly on the central shelf. Estuarine presence in warm 

 months, compiled from citations in the present study, is 

 marked by symbols. 



Sex ratios 



In the Hudson-Raritan Estuary, sex ratios of blue, lady, 

 and rock crabs were different from 1:1. In mature blue 

 crabs, the sex ratio favored females because the study 

 area is in the deeper oceanward portion of the estuarine 

 system, where females release their eggs and overwinter. 

 Many males spend their entire lives in water of relatively 

 low salinity (Van Engel, 1958), such as is found in the 

 nearby Hudson, Raritan, and Navesink-Shrewsbury 

 rivers. In the Navesink River, the sex ratio of male to 

 female blue crabs ;>12 cm over a two-year period was 

 2.6:1 (Meise and Stehlik, 2003). 



In the Hudson-Raritan Estuary, female lady crabs 

 a5 cm outnumbered males 2:1. Many of these females 

 were ovigerous and therefore estuarine use may be 

 related to reproduction. We were unable to locate pub- 

 lished reports of lady crabs or other Ovalipes spp. mat- 

 ing locations, single-sex migrations, or locations of lar- 



