178 



Fishery Bulletin 98(1) 



1 



•g 



s 



M. bilinearis 



1 



0.5 





 4 





 1000 



500 





 200 



100 





 20 



10 





 20' 



10 





 1 



0.5 



JlUi 



AL 



i 



JL 







1 



0.5 





 20 



10 







UJi 



I 



50 100 150 200 



0.5 





 1 



0.5 





 20 



10 







1[ 



0.5 





 1 



0.5 





 1 



0.5 







1 



0,5 



0.5 



Summer and fall settling fish 



L. profundorum 



m a HiJ- 



50 



100 



150 



C. arctifrons 



150 



Urophycis spp. 



150 200 



Standard length (mm) 



Figure 5 



Length frequencies by cruise of four species fMerluccius bilineans. Lepophidium profundorum. Cithanchthys arctifrons, and Uro- 

 phycis spp. ) that settled to the shelf between late summer and midfall. Plots for each species are ordered from top to bottom accord- 

 ing to the order of the 10 cruises (see Table 1 for cruise dates). Abundance on each cruise was standardized to the number offish 

 collected during 63 5-min tows (21 stations with 3 tows each). 



The origin represents the mean for each environ- 

 mental variable, and those means are weighted by 

 species abundance. Because of the numerical domi- 

 nance of P ferrugineus in the samples, its mean tem- 

 perature and depth of collection is driving the location 

 of the origin. Consequently, the location of P. ferrugin- 

 eus is just slightly left of the origin. The mean depth 

 distribution off! ferrugineus, however, was midshelf 

 and thus its abundance did not skew the species dis- 

 tributions about the second axis, CCA 2. 



One of the largest effects of the forward selection of 

 variables is that the third and fotuth CCA axes (Fig. 



9D ) now have definite environmental correlates. When 

 25 variables were used during fiill CCA, no one variable 

 stood out as a clear contributor to the variation along 

 these axes (Fig. 9B). With the abtmdance of scallops 

 being the important environmental gradient describing 

 the third CCA axis, one important species association is 

 made clear: the abundances of juvenile inquiline snail- 

 fish and scallops. The fourth CCA axis, representative 

 of longitude, accoimted for only 5% of the total environ- 

 mental explanation of the species patterns. This pat- 

 tern might be considered as the subtle variation among 

 the three transects (west, central, and east). 



