Krieger and Ito: Distribution and abundance of Sebastes borealis and S. aleutlanus 



269 



densities (Table 31, For all sites combined, habitats 

 with slopes greater than 20° contained greater den- 

 sities of rockfish than those with slopes less than 

 20° (Fig. 5). Slopes less than 20° were encountered 

 37% of the time and had 24% of the rockfish, whereas 

 slopes greater than 20° were encountered 63% of the 

 time and had 767f of the rockfish. 



Submersible counts versus trawl catch rates 



During the last four bottom-trawl surveys (1987, 

 1990, 1993, 1996), eight trawl hauls were completed 

 on the continental slope in southeastern Alaska and 

 234,100 m" of seafloor was sampled. The mean catch 

 rate was 3.2 rockfish/1000 m" for the 8 trawl hauls, 

 compared with the mean observation rate of 5.8 rock- 

 fish/1000 m- at the 15 dive sites. Catch rates exceeded 

 5.0 rockfish/1000 m- at only 2 of the 8 trawl sites, 

 whereas observation rates exceeded 5.0 rockfish/1000 

 m^ at 10 of the 15 dive sites. 



Discussion 



Because the two rockfish species were combined in 

 this study, we did not determine whether shortraker 

 rockfish behavior differs from rougheye rockfish be- 

 havior. They appear to share the same habitats, 

 -based on bottom-trawl sampling and observations 

 from the submersible, but differences may exist in 



