Abstract. -The megalopal stage 

 of Cancer oregonensis Dana is de- 

 scribed from both laboratory-reared 

 and naturally occurring populations 

 in the Puget Sound Basin. It is com- 

 pared with megalopae from natural 

 populations of C produdus Randall 

 collected in the same locale. Because 

 megalopal characters of C. produc- 

 tm from these northern populations 

 were found to differ significantly 

 from those described by Trask (1970) 

 for a California population, a rede- 

 scription of the megalopa of C. pro- 

 diictus based on the present collec- 

 tions is included. A key to the local 

 megalopae of Cancer species, based 

 on gross morphology, is presented. 



A Comparative Study 

 of the Megalopal Stages 

 of Cancer oregonensis Dana 

 and C. productus Randall 

 (Decapoda: Brachyura: Cancridae) 

 from the Northeastern Pacific 



Gregory A. DeBrosse 



Shannon Point Marine Center, Western Washington University 

 1900 Shannon Point Road, Anacortes. Washington 98221 

 Present address Rutgers University Shellfish Research Laboratory 

 P O Box 687. Point Norris, New Jersey 08349 



Adam J. Baldinger 



Shannon Point Marine Center, Western Washington University 

 1900 Shannon Point Road, Anacortes, Washington 98221 

 Present address: Department of Biology, San Francisco State University 

 San Francisco, California 94132 



Patsy A. McLaughlin* 



Shannon Point Marine Center, Western Washington University 

 1900 Shannon Point Road. Anacortes, Washington 98221 



Manuscript accepted 15 August 1989. 

 Fishery Bulletin, U.S. 88:39-49. 



The brachyuran crab genus Cancer 

 Linnaeus is recognized throughout 

 the world because of the major con- 

 tributions of some of its species to 

 commercial fisheries. Of the 13 Re- 

 cent species reported in the Eastern 

 Pacific (Nations 1975), four species, 

 C. gracilis Dana, C. rnagister Dana, 

 C. oregonensis Dana, and C. produc- 

 tus Randall, coexist in the Puget 

 Sound Basin of Washington and Bri- 

 tish Columbia (Orensanz and Galluc- 

 ci 1988). A fifth species, C. branneri 

 Rathbun, has also been reported 

 from the region (e.g., Rathbun 1904 

 [as C. gibbosulus DeHaan], 1930; 

 Schmitt 1921 [as C. gibbosulus]; 

 Kozloff 1974, 1987; Hart 1982). How- 

 ever, the only verified occurrences of 

 C. branneri have been those cited by 

 Rathbun (1904) for a single male 

 from Port Althorp, Alaska (Natl. 

 Mus. Nat. Hist., USNM 12516), and 



'Reprint requests should be sent to this author. 



a second single male from Ucluelet, 

 west coast of Vancouver Island, B.C. 

 (USNM 40078). A specimen from 

 Vancouver Island identified as C. 

 branneri (Calif. Acad. Sci., CAS 

 015782) has proved to be C. oregonen- 

 sis (personal examination). All subse- 

 quent records of C. branneri from 

 tlie northeastern Pacific, north of the 

 Oregon coast, are merely range list- 

 ings based upon this early Rathbun 

 material. 



Of the four species indigenous to 

 Puget Sound, Cancer rnagister {Dun- 

 geness crab) is the most thoroughly 

 studied because of its commercial 

 significance. However, catch records 

 throughout its range exhibit consid- 

 erable interannual fluctuations (Bots- 

 ford 1986). Because of these fluctua- 

 tions, fishery biologists have begim 

 to examine the life history and larval 

 dynamics of r. rnagister {e.g., Lough 

 1976, Reilly 1983). These studies 

 suggested that larval and postlarval 



39 



