Williams and Ralslon: Distribution and co-occurrence of Sebastidae off California and Oregon 



851 



100 200 300 400 100 200 300 400 



Depth (m) 



Figure 9 



Plot of rockfish CPUE estimates by depth and latitude from the AFSC triennial 

 bottom trawl survey. Circle diameters are proportional to the square root of rockfish 

 CPUE and the bold plus symbol represents the centroid of the CPUE estimates. 



ciations (see Weinberg, 1994). Furthermore, overfishing 

 of rockfish stocks may alter spatial distributions. A good 

 example is cowcod, which has shown a dramatic decline in 

 abundance in recent years within the southern California 

 Bight; most of the remaining population resides in rela- 

 tively deep water (Butler et al.^). 



Because the total abundance of each species of rockfish 

 may have affected the results of the assemblage analy- 

 sis, the species distributions were carefully re-examined 

 and a final assemblage structure determined (Table 5). 



The changes from Table 4 for the k=4 groups include the 

 placement of greenspotted rockfish into the southern shelf 

 assemblage and canary and yellowtail rockfish into the 



3 Butler, J. L., L. D. Jacobson, J. T. Barnes, H. G. Moser, and R. 

 Collins. 1999. Stock assessment of cowcod. /n Pacific Fish- 

 ery Management Council, Status of the Pacific Coast groundfish 

 fishery through 1999 and recommended biological catches for 

 2000: stock assessment and fishery evaluation. Pacific Fishery 

 Management Council, 2130 SW Fifth Ave., Suite 224. Portland, 

 Oregon 97201. 



