40 
Fishery Bulletin 112(1) 
Table 1 
Groundfish species that were included in cluster analyses and the percentage of “inshore” and 
“offshore” tows during which they were observed for the period of 2002-09 in the groundfish 
fishery of the U.S. west coast. Inshore was defined as all tows occurring at an average depth of 
274 m (150 fathoms) or less. Offshore tows were those for which the average depth was greater 
than 150 fathoms. Rebuilding rockfish species and their respective percentages on inshore and 
offshore tows are underlined. Major target species are noted by an asterisk. 
Common name 
Scientific name 
% of 
inshore tows 
% of 
offshore tows 
Arrowtooth Flounder* 
Atheresthes stomias 
64.5 
55.7 
Aurora Rockfish 
Sebastes aurora 
0.7 
25.9 
Big Skate 
Raja binoculata 
26.8 
1.3 
Bocaccio 
Sebastes paucispinis 
5.3 
0.9 
Canarv Rockfish 
Sebastes oinniger 
18.2 
0J3 
Cowcod 
Sebastes levis 
L3 
0T 
Darkblotched Rockfish 
Sebastes crameri 
15.7 
18.2 
Dover Sole* 
Microstomus pacificus 
75.1 
93.0 
English Sole* 
Parophrys vetulus 
80.7 
10.5 
Flathead Sole 
Hippoglossoides elassodon 
20.5 
0.1 
Greenstriped Rockfish 
Sebastes elongatus 
28.4 
1.3 
Grenadiers 
Macrouridae 
0.4 
12.8 
Lingcod 
Ophiodon elongatus 
65.2 
9.4 
Longnose Skate* 
Raja rhina 
48.3 
48.3 
Longspine Thornyhead* 
Sebastolobus altivelis 
0.3 
60.9 
Mixed Thornyheads* 
Sebastolobus spp. 
0.3 
13.0 
Other rockfish 
Sebastes spp. 
6.9 
28.0 
Other sanddabs 
Citharichthys spp. 
33.4 
0.1 
Other skates 
Rajiformes 
61.4 
40.0 
Pacific Cod 
Gadus macrocephalus 
28.2 
1.0 
Pacific Flatnose 
Antimora micolepis 
0.0 
21.3 
Pacific Grenadier 
Coryphaenoides acrolepis 
0.0 
22.6 
Pacific Hake 
Merluccius productus 
56.0 
70.9 
Pacific Halibut 
Hippoglossus stenolepis 
44.8 
22.6 
Pacific Ocean Perch 
Sebastes alutus 
2J5 
15.8 
Pacific Sanddab 
Citharichthys sordidus 
48.7 
0.5 
Petrale Sole* 
Eopsetta jordani 
85.7 
22.4 
Redbanded Rockfish 
Sebastes babcocki 
2.5 
13.0 
Rex Sole* 
Glyptocephalus zachirus 
81.6 
47.7 
Rosethorn Rockfish 
Sebastes helvomaculatus 
2.3 
9.0 
Sablefish* 
Anoplopoma fimbria 
50.0 
95.2 
Shortspine Thornyhead* 
Sebastolobus alascanus 
5.4 
87.8 
Pacific Spiny Dogfish 
Squalus suckleyi 
57.7 
33.9 
Splitnose Rockfish 
Sebastes diploproa 
4.4 
30.5 
Spotted Ratfish 
Hydrolagus colliei 
70.9 
30.0 
Widow Rockfish 
Sebastes entomelas 
T9 
L6 
Yelloweve Rockfish 
Sebastes ruberrimus 
L3 
0T 
part of the shelf cluster, but this result was not con- 
firmed by partitioning analysis. These groups were con- 
sistent with those found by Cope and Haltuch (2012), 
who used fishery-independent data. Species were iden- 
tified as slope or shelf species on the basis of their 
depth distribution in the groundfish bottom trawl sur- 
vey (Keller et al., 2012). 
All of the species shown to cluster in this first round 
of analysis were relatively common, occurring on at 
least 35% of tows (Table 1). These species were the only 
ones to form clusters more readily than fakies, which 
were grouped at a silhouette value just above 0.25 in 
each PA (consistent with the recommendation of Kauff- 
man and Rousseeuw [2005]) and at a distance of ap- 
proximately 0.4 in the HCA (consistent with Weinberg 
[1994]). Rebuilding and less common species were not 
components of clusters at a coastwide level and clus- 
tered less readily than fakies, which had been simu- 
lated to occur at random. 
Similar trends were observed when the data were 
broken out by year. Only the most common species 
formed clusters more readily than fakies on an annual, 
