FISHERY BULLETIN: VOL. 82, NO. 3 



CO 

 CL 



t — i 

 LU 



>- 

 CD 



o 



» — I 



o 



2.0 



1.5  



1.0  



0.5  



0.0  



0.5 



1.0 



1.0 1.2 1.4 1.6 1.8 2.0 



L0G10 (CRRRPRCE WIDTH IN MM) 



2.2 



FIGURE 8. — Regression of log lo dry weight (g) on log, carapace width (mm) for 87 male 

 (12-132 mm) and 74 female (15-115 mm) Cancer magister from Grays Harbor, Wash. 

 Observations ( + ), regression line (solid), and 95% confidence interval about the regression line 

 (dashed) are shown. 



instar crabs (7 mm cw) of 0.02 g dry weight in- 

 creased in dry biomass 282 times by the time they 

 reached the 6th or 7th instar (about 50 mm cw), 

 weighing 5.7 g the following April (Fig. 9). Some 

 may have reached 70 mm by that time, weighing 

 14.7 g, an increase of over 700-fold. Second-year 

 crabs increased in dry biomass 5.3 times, from 4.0 

 to 21.5 g. Third-year crabs increased from 24 to 99 

 g, a dry biomass increase of 4.1 times. 



DISCUSSION 



Recruitment and Distribution 

 in the Estuary 



Megalops larvae probably metamorphosed to 

 the first postlarval stage in Grays Harbor, since 

 trawl collections included second instars on 4 May 

 1980 and first instars in April and May 1981. Cast 

 exuviae of these stages were abundant on beaches 

 of the outer estuary in early May 1982. Larval 

 densities in the estuary were at the low end of the 



range of densities found by Lough (1976) off the 

 Oregon coast in 1970-71 (100-8,000/1,000 m 3 ). In 

 contrast, no megalops larvae were found in San 

 Francisco-San Pablo Bays during 4 yr of surveys 

 by the California Department of Fish and Game, 

 which concluded that crabs entered that estuarine 

 system only after metamorphosis (Orcutt et al. 

 1975, 1976). 



Once inside Grays Harbor, C. magister showed 

 an ontogenetic change in habitat selection, i.e., 

 centers of abundance changed with age. Eelgrass 

 beds may be the preferred habitat of the first post- 

 larval stages, because catches of 0+ crabs were 

 most abundant near those areas (Figs. 5, 6). Butler 

 (1956) also found that the most abundant concen- 

 trations of early instars along the northern shore 

 of Graham Island, Canada, were associated with 

 the presence oiZostera marina in sheltered inlets. 

 However, this age class was widely distributed 

 from stations 1 to 9. 



Crabs in the 1+ age group (size range 50-90 mm 

 cw) were the most abundant. Although their dis- 



478 



