FISHERY BULLETIN: VOL. 86, NO. 3 



Table 4.— Tow characteristics and number of Cancer magister megalopae (10 m^^ of sea surface) caught by 0.25 m 



bongo tows off Tofino, B.C., on 31 May and 14 June 1985. 



Cross-Shelf Spatial Distribution 



With both species, no clear pattern in cross-shelf 

 distribution was evident from the April data, per- 

 haps because of relatively low overall megalopal 

 abundance. In late May (Table 2), scaled abundance 

 (weighted as to time of night) of C. magister was 

 highest at 93 km offshore, but megalopae were 

 generally abundant (>10 10 m"^ sea surface) from 

 46 to 148 km offshore. In mid-June, the basic pat- 

 tern observed in late May was still evident, although 

 megalopal abundance near shore had declined (Table 

 3). Highest estimated C. magister abundance was 

 at 56 km offshore. 



With C. oregonensis, scaled abundance in late May 

 peaked (>20 10 m' 2) 93-111 km offshore (Table 2). 

 An exceptionally large number of megalopae (4,671 

 10 m"^) was found 9 km offshore in June (Table 3), 

 while from 56 to 111 km offshore, abundance re- 

 mained high (>20 10 m- 2). 



Sampling of inlet waters around Tofino with 

 neuston gear showed that a few Cancer megalopae 

 were present but that no substantial (average was 

 <1 10 m~2) numbers occurred. Maximum C. ma- 

 gister megalopal abundance was 2.9 megalopae 10 

 m"^ on 5 June, with megalopae observed only be- 

 tween 29 May and 19 June. Maximum C. oregonen- 

 sis abundance was 2.3 megalopae 10 m"^ on June 

 19, with megalopae observed only between 4 and 

 19 June. 



Intermolt Stage 



All C. magister megalopae collected in April were 

 of early developmental stage (Fig. 6), whereas all 

 those collected in August were mid-stage mega- 

 lopae. In May, June, and July, the general pattern 



of offshore distribution by molt stage was for late 

 stage larvae to be nearest inshore and early stage 

 larvae to be furthest offshore. 



Cancer oregonensis megalopae had a similar 

 developmental distribution pattern to those of C 

 magister (Fig. 7); late molt megalopae were most 

 abundant closest to shore. However, in late May, 

 most megalopae were early stage, in contrast to C. 

 magister, whereas by mid-June, all three intermolt 

 groups were present. 



When the scaled megalopal abundance at distance 

 offshore (Tables 2, 3) is multiplied by the percent- 

 age at each molt stage at a specific location (Figures 

 6, 7, for each species, respectively), the actual abun- 

 dance by molt group with distance offshore is deter- 

 mined (Figures 8, 9, respectively). In late May, late 

 stage C. magister megalopae were relatively abun- 

 dant 9 km offshore, indicating that some Dungeness 

 crab settlement may have occurred. However, lar- 

 val sampling in the inlets and bays showed few 

 megalopae present. In contrast to previous years, 

 no recently settled juvenile crabs (0 age-class crabs) 

 were found by local fishermen in intertidal areas or 

 on floating objects, confirming that the magnitude 

 of megalopal settlement in 1985 was relatively small. 

 In mid- June, there were few C. magister megalopae 

 of any intermolt stage present within 40 km of the 

 coast and little evidence of late stage megalopae off- 

 shore. Early and mid-stage megalopae were most 

 abundant from 56 to HI km offshore. 



For C. oregonensis, the opposite was observed 

 (Fig. 9). Few late stage megalopae were present in 

 late May, and unlike C. magister, megalopae were 

 not concentrated in nearshore waters. However, 

 megalopae in all three intermolt stages were abun- 

 dant inshore in mid-June, with late stage megalopae 

 dominating at the coast. The timing of occurrence 



534 



