Jagielo et al.: Demersal groundfish densities In trawlable and untrawlable habitats off Wasfilngton 



551 



the dive sites designated trawlable 

 prior to the video transect survey, 

 mud bottom predominated (78.5%), 

 followed by pebble (11.5%), mud- 

 pebble (3.7%), and pebble-cobble 

 (3.3%). At the sites designated a 

 priori to be untrawlable, pebble 

 bottom was most common (62.0%) 

 followed by pebble-boulder ( 14.6% ), 

 mud (7.8%), boulder-pebble (6.3%), 

 and boulder-cobble (6.0%). Micro- 

 habitat classifications unique to 

 untrawlable habitat comprised 

 14.5% of the total and included 

 cobble-pebble, cobble, boulder- 

 pebble, boulder-cobble, rock-ridge, 

 boulder, and cobble-boulder. The 

 mud-pebble microhabitat was ob- 

 served at trawlable sites but not at 

 untrawlable sites. Bottom pertur- 

 bations, which we presumed were 

 trawl-door tracks, were observed at 

 6 of 8 a priori trawlable locations 

 (sites 4, 5, 10, 12, 13, and 15), and 

 at 2 of 8 a priori untrawlable loca- 

 tions (sites 3 and 14). 



We counted 3647 fishes repre- 

 senting 26 species or generic group 

 classifications (Table 3). Some 

 fishes were readily identifiable to 

 species; for example, lingcod, rat- 

 fish {Hydrolagus colliei), canary 

 rockfish iSebastes pinniger), and 

 wolf-eel (Anarrhichthys ocellatus) 

 were very distinctive. Other fishes 

 could not always be identified 

 to species level. In such cases, 

 fish were assigned to the generic 

 groups of "unidentified" rockfish, 

 flatfish, or roundfish. It is likely 

 that greenstriped (S. elongatus), 

 redstripe (S. proriger), rosethorn 

 (S. helvomaciilafus), silvergray (S. 

 brevispinis), and yellowtail rock- 

 fish (S. flavidus) were sometimes 

 classed as unidentified rockfish; 

 more rarely, large quillback (S. 

 maliger), tiger (S. nigrocinctus), 

 and yelloweye rockfish (S. ruber- 

 rimus) may have been assigned 

 to this category. Flatfish were 

 very difficult to identify to species; 

 it is very likely that arrowtooth 

 iAtheresthes stomias), Dover sole 

 (Microstomus pacificus) and Pa- 

 cific halibut (Hippoglossus stenol- 

 epis) were sometimes classed as 

 unidentified flatfish. 



The reliability of our fish counts 

 was in part a function of fish size. 



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