Ryer et al.: Depth distribution, habitat associations, and differential growth of Chionoecetes bairdi 
257 
also an understanding of ecological processes that 
contribute to the strength of upcoming year classes 
so that fisheries may be scaled to predicted future re- 
source availability. For depressed stocks, recovery be- 
gins with the recruitment of one or more strong year 
classes. Establishment of a strong year class depends 
upon adequate spawning stock, transport of larvae 
from spawning to nursery grounds (Etherington and 
Eggleston, 2003), appropriate settlement substrate 
(Wahle and Steneck, 1991), and favorable postsettle- 
ment processes (Heck et a!., 2001). 
Little is known about nursery areas and preferred 
habitats for newly settled juveniles of these North Pa- 
cific crab species. Red king crab juveniles are strongly 
attracted to shallow-water, structured habitat, such as 
cobble, algae, and hydroids (Sundberg and Clausen 1 ; 
McMurray et al. 2 ; Loher and Armstrong, 2000), which 
mediates their interactions with predators and larg- 
er conspecifics (Loher and Armstrong, 2000; Stevens, 
2003a; Stoner, 2009; Pirtle and Stoner, 2010, Sund- 
berg and Clausen 1 ; McMurray et al. 2 ). Yet, most of this 
knowledge has been gained through laboratory studies 
or the outplanting of hatchery-reared crabs; too few ju- 
veniles are encountered in the wild to make firm con- 
clusions. Similarly, newly settled Tanner crabs are not 
effectively sampled by conventional sampling gears, 
and there is a dearth of information on their habi- 
tat preferences and early ecology. Unlike king crabs 
( Paralithodes spp.), it is believed that Tanner crabs 
show an affinity for burial in unconsolidated sediment 
throughout their lives (Rosenkranz et ah, 1998), indi- 
cating lower reliance on structured habitat during the 
juvenile period when crabs presumably experience high 
mortality. 
We have conducted studies on the ecology and 
habitat preferences of juvenile flatfish species that 
use shallow-water nurseries around Kodiak Island in 
the Gulf of Alaska since 2002. During 2002 and 2003, 
we conducted beam trawl hauls in Pillar Creek Cove 
(hereafter Pillar) and estimated densities of age-0 Tan- 
ner crabs to be <0.05 crabs/m 2 (senior author, unpubl. 
data). Although not quantified in subsequent years, 
densities of age-0 Tanner crabs appeared to remain low. 
However, in 2009, we began to encounter larger num- 
bers of age-0 Tanner crabs in beam trawl hauls and, 
again, began enumerating them. Beam trawl hauls 
conducted over a range of depths indicated that crabs 
were at their highest density, ~2 crabs/m 2 , at depths 
of 15-30 m (senior author, unpubl. data). This depth 
range also corresponded to the depths where we docu- 
1 Sundberg, K., and D. Clausen. 1977. Post-larval king crab 
(Paralithodes camtschatica) distribution and abundance in 
Kachemak Bay, Lower Cook Inlet, Alaska, 1976, vol. 5, 36 p. 
Environmental studies of Kachemk Bay and Lower Cook In- 
let (L. Trasky, L. Flagg, and D. Burbank, eds.). Alaska Dep. 
Fish Game, Anchorage, AK. 
2 McMurray, G., A. H. Vogel, and P. A. Fishman. 1984. Dis- 
tribution of larval and juvenile red king crabs ( Paralithodes 
camtschatica) in Bristol Bay. OCSEAP Final Rep. 53:267- 
477. 
mented extensive areas of habitat created by the tubes 
of the ampharetid polychaete Sabellides sibirica. This 
polychaete has been shown to influence the depth dis- 
tribution of juvenile northern rock sole (Lepidopsetta 
polyxystra) (Ryer et al., 2013). 
The densities of juvenile Tanner crabs during sum- 
mer in Kodiak embayments remained high from 2009 
through 2011, in the range of 2-10 crabs/m 2 . Although 
it is too soon to conclude that populations of Tanner 
crabs are rebuilding in the Gulf of Alaska, the occur- 
rence of high densities of juvenile crabs has provided an 
opportunity to study early life-stage ecology of a com- 
mercially important species in Alaska waters. In this 
study, we specifically examined 1) the depth distribu- 
tion of newly settled crabs and how it changes through 
the summer, 2) the possible association between crabs 
and habitat created by polychaete worm tubes, and 3) 
differences in crab size and distribution between em- 
bayments with varying characteristics of sediment and 
physical exposure. Together, these efforts represent the 
first significant study aimed at understanding impor- 
tant facets of the habitat ecology of newly settled Tan- 
ner crabs. 
Material and methods 
Study sites 
Field work was conducted at 4 sites in the coastal wa- 
ters around the eastern end of Kodiak Island, Alaska 
(Fig. 1). Two of these sites, Holiday Beach (hereaf- 
ter Holiday; 57°41.344'N, 152°27.958'W) and Pillar 
(57°49.136'N, 152°25.314'W), have been the focus of 
juvenile flatfish habitat studies (Hurst and Abookire, 
2006: Ryer et ah, 2007; Stoner et al., 2007; Ryer et al., 
2013). Both sites have gently sloping, sandy bottoms 
just offshore from beaches that are exposed to wave 
action from the Gulf of Alaska. The third site, in Kalsin 
Bay (hereafter Kalsin; 57°36.207'N, 152°26.890'W), also 
is characterized by a gently sloping bottom, but it has 
finer sediments because of its more protected location 
near the head of the bay. The last site, Womens Bay 
(hereafter Womens; 57°42.800'N, 152°31.134'W), has a 
narrow entrance with a relatively shallow sill (depth 
-11 m) and offshore islands, which protect the inner 
bay from wave action. This fourth site is also charac- 
terized by a gently sloping bottom, but sediments are 
finer there than at the other 3 sites being composed of 
silty sands and muds. 
Salinity and water temperature in spring and sum- 
mer were generally comparable between sites, ranging 
from 28-32 and 5-1 1°C, respectively, for all 4 sites. 
During 2011, temperature loggers were deployed on 
the bottom at each site at a depth of 15 m mean lower 
low water (MLLW) on 20 May and recovered on 22 Au- 
gust. After recovery of loggers, temperature data were 
downloaded, averaged by day for each site, and then 
analyzed with analysis of variance (ANOVA) to deter- 
mine if there were differences between sites. 
