Stem et al.. Fish-habitat associations at edge of Oregon continental shelf 



547 



Hud & Sand - 



Sand & Ridge - 



Cobble i Ridge - 



Boulder & Flat Rock - 



Boulder & Hud - 



Boulder & Ridge - 



Ridge & Cobble - 



Cobble & Sand - 



Sand & Mud - 



Pebble i Cobble - 



Ridge & Boulder - 



Ridge & Sand - 



Boulder S, Sand - 



Sand & Cobble - 



Sand & Boulder 



Sand - 



Cobble & Boulder - 



Mud i Pebble - 



Boulder & Cobble - 



Cobble i Mud - 



Flat Rock 



Cobble ■ 



Hud & Boulder 



Hud i Cobble ■ 



Ridge - 



Boulder 



Hud 



0.25 

 Euclidean distance 



0.50 



Figure 4 



Cluster analysis of all observed bottom types based on the relative abundances of 21 

 fish taxa (see Table 4 for species list). 



In general, the degree of bot- 

 tom-type relief varied inversely 

 with depth (Fig. 5). High relief 

 substrates such as rock ridges, 

 boulder, and cobble occurred at 

 relatively shallow 80-100 m depths, 

 while low-relief muddy substrates, 

 such as mud and boulder, mud 

 and cobble, and pure mud, oc- 

 curred relatively deeper, at 160- 

 240 m depths (Fig. 5). 



CCA described associations be- 

 tween species abundance and the 

 distribution of specific habitat 

 types (Table 4, Fig. 6). Bartlett's 

 test indicated that the first three 

 axes represented significant 

 canonical correlations. The low 

 values of the redundancy coeffi- 

 cient for these axes (0.10-0.03, 

 measuring variability in fish abun- 

 dance explained by habitat varia- 

 tion) demonstrated strong corre- 

 lations between several species 

 and habitats rather than general 

 associations among all species 

 and all habitats. 



