JAMIESON and PHILLIPS: OCCURRENCE OF CANCER CRAB MEGALOPAE 



Figure 6.— Percentage of the three Cancer 

 magister megalopal intermolt groups observed 

 at each station during the April to August 1985 

 surveys. 



LlI 



o 



UJ 

 CL 



LU 

 O 

 CC 

 LlI 

 CL 



(a) APRIL 16/17, 1985 

 2 33 2 



(- 

 z 



UJ 



o 

 tr 



LU 

 CL 



(b) may 30/31 



100 



80- 

 60- 

 40 

 20 

 



25 



25 



25 



o— o.. 



(c) JUNE 16 



® 



5 4 25 24 

 17 25 25 



(e) august 23/26 



100 -, 

 80 

 60 

 40 

 20 







— t \ 1 1 



40 80 120 140 



DISTANCE (Km) 



JULY 6/7 

 63 3 2 



40 80 120 

 DISTANCE (Km) 



C. magjster 



INTERMOULT STAGES 



o o 



 a 



1-4 

 5-8 

 9-13 



n= 10 unless otherwise 



specified above graph 



of late stage megalopae at the coast thus differed 

 between the two species. 



Inshore Benthic Sampling 



Survey of commercial crab habitat with beam 

 trawls and an epibenthic sled yielded few newly 

 settled megalopae or juvenile C magister (Table 5). 

 A maximum of 83 crab/10,000 m^ was collected, 

 well below densities which might be expected if 

 settlement had been substantial. No C. oregonensis 

 were caught, perhaps because of the habitat being 

 sampled, and no larval settlement of either species 

 was observed when intertidal mud flat areas were 

 searched by foot. In a concurrent study, no signifi- 



cant abundance of age-class C. magister was 

 observed during monthly sampling throughout the 

 remainder of the year. 



DISCUSSION 



Megalopal Source 



Temporal duration of C. magister larval stages has 

 been estimated both by laboratory rearing (Poole 

 1966; Reed 1969; Brugman 1972; Gaumer 1973; 

 Ebert et al. 1983) and the first appearances of lar- 

 val stages in field studies (Poole 1966; Lough 1976; 

 Reilly 1983). The length of the total larval period 

 has been estimated as 105-125 days by Reilly (1983), 



535 



