560 



Fishery Bulletin 101(3) 



Table 11 



Comparison offish density estimates (average number offish/hectare) in trawlable (D,) and untrawlable (D„) habitats from sub- 

 mersible studies in Washington, Oregon, and California. Densities for italicized species were reported in all three studies. 



Washington (present study) 



Oregon ' 



Species 



D, 



D„ 



D. 



D.. 



California- 



D, 



D.. 



Rockfish 

 Bank rockfish 

 Bocaccio 



Canary rockfish 0.41 



Cowcod 



Darkblotched rockfish 

 Greenblotched rockfish 

 Greenspotted rockfish 

 Greenspotted and greenblotched rockfish 

 Greenstriped rockfish 5.65 



Halfbanded rockfish 

 Pygmy rockfish 

 Quillback rockfish 

 Redstripe rockfish 



Rosethorn rockfish 0.48 



Sharpchin rockfish 

 Shortspine thomyhead 

 Stripetail rockfish 



Tiger rockfish 0.24 



Widow rockfish 

 Yelloweye rockfish 

 Yetlowtail rockfish 0.24 



Flatfish 



Arrowtooth flounder 9.25 



Dover sole 9-33 



Pacific halibut 6.88 



Other Fish 

 Eelpout 11-46 



Greenling 



Lingcod '■■'?-9 



Pacific cod 0.70 



Pacific hagfish 

 Pacific hake 

 Poachers 



Spotted ratfish 1-54 



Salmon 0.28 



Skate 2.81 



Spiny dogfish 167 



Wolf-eel 



0.36 



3.76 



0.27 



3.39 



77.78 



4.40 



3.90 

 1.11 

 0.49 



165.00 

 510.00 



479.50 

 119.50 



93.00 



7.50 



15.00 



9.00 



58.00 



43.67 



3.00 



91.67 



' Oregon data source: Table ,3 of Stein et al. (1992). Categories "mud" and mud-cobble" were averaged and used as a proxy for trawlable habitat; 



categories "flat rock" and "rock ridge" were averaged and used as a proxy for untrawlable habitat. 

 -' California data source: Table 2 of Yoklavich et al. (2000) Categories "mud," "cobble-mud" and "mud-pebble" were averaged and used as a proxy for 



trawlable habitat; categories "rock-mud," "rock ridge," and "rock boulder" were averaged and used as a proxy for untrawlable habitat. 



submersible, 3) variation in countability due to habitat type; 

 for example, due to reduced visibility when the submersible 

 maneuvered ofTbottom to avoid large boulders, or the failure 

 to detect fish hiding behind boulders, and 4) the limitation 

 of the technique to quantifying the density of benthic spe- 



cies found in close proximity to the bottom. The advantages 

 of the visual transect survey method include the ability to 

 1) sample in habitats that are inaccessible to other survey 

 methods, 2) observe /;; situ fish behavior, and 3) observe the 

 distribution of fish and fish-habitat associations on a fine 



