42 
Fishery Bulletin 112(1) 
Distances 
0.0 
0.2 
I 
0.4 
I 
0.6 
I 
0.8 
1.0 
Longspine Thornyhead 
Pacific Flatnose — 
Pacific Grenadier 
Yelloweye Rockfish 
Widow Rockfish 
Bocaccio 1 
Cowcod ' 
Shelf 
cluster 
Grenadiers 
Mixed Thorhyheads 
Flathead Sole| 
Pacific Cod i 
Canary Rockfish 
Greenstriped Rockfish 
Redbanded Rockfish -< 
Rosethorn Rockfish H 
Pacific Ocean Perch 
Darkblotched Rockfish — 
Splitnose Rockfish — 
Aurora Rockfish 
Other Rockfish 
Pacific Halibut ■ 
Other Skates — — j- 
Pacific Spiny Dogfish 
Spotted Ratfish 
Lingcod 
English Sole 
Petrale Sole 
fake species 3 
fake species 2 
fake species 5 
fake species 1 - 
fake species 4 - 
Longnose Skate 
Pacific Hake - 
Slope Shortspine Thornyhead 
cluster Dover S°!e i 
Sablefish — 1 
Arrowtooth Flounder 
Rex Sole 
Big Skate 
Pacific Sanddab f~ 
Other Sanddabs — — t- 
Figure 2 
Dendrogram of species clusters determined with hierarchical cluster analysis for the entire 
geographic range of the demersal trawl fishery for all years (2002-09). Fake, simulated species 
(“fakies”) were included in the analysis as a means of identifying the dissimilarity distance for 
identifiable clusters. A dashed line shows the dissimilarity distance attributed to fakies (i.e., the 
breakpoint less than which clusters are considered to be identifiable). The distance axis represents 
dissimilarity measures determined from the cluster analysis. Two clusters are evident, a slope 
cluster consisting of demersal species associated with the continental slope, and a shelf cluster 
consisting of species commonly associated with the continental shelf. Groupings that included 
rebuilding species all had dissimilarity distances that were greater than randomly simulated 
“fakies.” 
trawl fishery. Rebuilding species that are associated 
with continental shelf habitats (Canary Rockfish, Yel- 
loweye Rockfish, and Bocaccio) did tend to cluster more 
closely with shelf target species such as English Sole, 
Petrale Sole, and Lingcod. However, they were all still 
part of a larger cluster that also included Sablefish, 
Dover Sole, and other slope species. These large clus- 
ters had a silhouette value <0.25 (for PA analyses) 
and a distance measure less than 0.4 (for HCA), both 
indicating insignificant groupings. Rebuilding species 
were grouped with the most common species by de- 
fault. When a rebuilding species was caught, a series 
of other commonly occurring target species were likely 
to have been caught as well, but the opposite could not 
be stated. As an example, a tow in which Canary Rock- 
fish was caught was also likely to have caught Petrale 
