FISHERY BULLETIN: VOL. 87. NO. 4. 1989 



thrusters off for about 10 minutes. The lights 

 were then turned on to determine their effects 

 on fish behavior. Although "marine snow" was 

 sometimes dense, visibility near the bottom was 

 3-5 m on all dives. Observations were some- 

 times made with ambient light from the submer- 

 sible's conning tower at shallow depths. 



A hierarchical cluster analysis (see Pimentel 

 1979), using presence or absence of species, was 

 used to determine the similarity of nonschoohng 

 fish assemblages among transects. Schooling 

 fishes were not included because most were 

 small and could not be accurately enumerated or 

 identified to species. 



RESULTS 



We encountered diverse and patchy sub- 

 strates. Bottom types ranged from soft mud to 

 rock walls and pinnacles. The bottom was often 

 mud at depths below about 150 m, and cobble or 

 rock at shallower depths. Massive rock forma- 

 tions, often sculptured into ridges and valleys, 

 existed at depths of 75 m or less. Although habi- 

 tats were generally stratified by depth, bottom 

 type typically varied within a dive. 



We observed a total of 42 taxa of fishes, includ- 

 ing 31 identified species (Table 1). Rockfishes 

 (Scorpaenidae) were by far the most abundant 

 and speciose group: 12 species of Sebastes were 

 identified. Of the nonschooling fishes, small 

 "blotched" rockfishes, tentatively identified as 

 sharpchin rockfish, S. zacentrus, were seen 

 more frequently on transects of contour dives 

 than all other fishes combined (Table 1). Rock- 

 fishes ranked first in abundance on 15 transects 

 and second in abundance on 10 of the 21 tran- 

 sects (Table 2). The most numerous of the identi- 

 fied nonschooling species was the rosethorn 

 rockfish, Sebastes lielvomaculatus. The most 

 numerous of the identified schooling species 

 was yellowtail rockfish, S. flavidus; sometimes 

 nonschooling individuals of this species were 

 seen. 



Table 1 . — Rank order of abundances of nonschooling fishes 

 seen on the 21 transects on Heceta Bank. 



Nonschooling fishes 



Total no. 

 observed 



Sharpchin rockfish, Sebastes zacentrus? 949 



Unidentified small rockfish 902 



Rosethorn rockfish, Sebastes helvomaculatus 409 



Zoarcidae 1 64 



Sablefish, Anoplopoma fimbria 140 



Pygmy rockfish, Sebastes wilsoni? 132 



Slender sole, Lyopsetta exilis 99 



Dover sole, Microstomus pacificus 97 



Unidentified large rockfish 71 



Agonidae 67 



Greenstriped rockfish, Sebastes elongatus 55 



Unidentified flatfish 52 



Cottidae 51 



Hagfish 40 

 Shortspine thornyhead, Sebastolobus alascanus 33 



Slim sculpin, Radulinus asprellus 33 



Rex sole, Glyptocephalus zactiirus 33 



Splitnose rockfish. Sebastes diploproa 32 



Yelloweye rockfish, Sebastes ruberrimus 25 



Canary rockfish, Sebastes pinniger 25 



Kelp greenling, l-lexagrammos decagrammus 23 



Unknown fish 21 



Darkblotched rockfish, Sebastes crameri 19 



Yellowtail rockfish, Sebastes flavidus 16 



Ur\gco6, Optiiodon elongatus 14 



Spotted raffish, Hydro/agus co///e/ 12 



Longnose skate, ffaya r/i/na 10 



Blenniidae 8 



Bathymasteridae 8 



Rajidae 7 



English sole, Parophrys vetulus 7 



Redbanded rockfish, Sebastes babcocki 7 



Arrowtooth flounder, Attieresthes stomias 6 



Big skate. Raja binoculata 4 



Pacific hake, t\/lerluccius productus 4 



Tiger rockfish, Sebastes nigrocinctus 2 



Wolf-eel, Anarrhiichithys ocellatus 2 



Sand sole, Psettictithys melanostictus 2 

 Stripetail rockfish, Sebastes saxicola 

 Ragfish, Icosteus aenigmaticus 

 Sand dab, Cittiarichttiys sp. 

 Threadfin sculpin, Icelinus filamentosus 

 Osmendae 

 Greenspotted rockfish, Sebastes chlorostictus 



Assemblages of Nonschooling Fishes 



Cluster analysis grouped the nonschooling 

 fishes into two major groups associated with two 

 major habitat types and two depth zones — bot- 

 toms where rock and cobble predominated at 

 depths of 67-145 m (Habitat 1:13 transects) and 

 mud and cobble bottoms at depths of 140-299 m 

 (Habitat 11:8 transects) (Fig. 3, Table 2). Two 

 subclusters occurred within each habitat group 



at a Euclidian distance of <0.4. The distance 

 (dissimilarity) between the two major habitat 

 types was almost twice as great as among the 

 four subclusters. As can be seen in Table 2, dif- 

 ferences in species compositions among clusters 

 were not large. Many species were found in sev- 

 eral habitat/depth types. Distinct species assem- 

 blages were not obvious. The four habitat groups 

 were as follows: 



958 



