256 
NOAA 
National Marine 
Fisheries Service 
Abstract— We examined depth dis- 
tribution, habitat association, and 
growth of newly settled southern 
Tanner crab ( Chionoecetes bairdi) 
at 4 sites around the eastern end 
of Kodiak Island, Alaska, during 
2010 and 2011. Settlement was from 
April through July, and crab den- 
sity peaked during May-July, at 10 
crabs/m 2 in 2010 and 2.3 crabs/m 2 
in 2011. By the end of August most 
crabs had progressed through 3-5 
molt stages (instars). An associa- 
tion between crabs and tubes of the 
ampharetid polychaete Sabellides 
sibirica was observed in 2010, but 
it was not seen in 2011 when both 
crabs and worms were less abun- 
dant. Crabs in protected embay- 
ments were larger in August than 
crabs at open coastal sites. Crabs at 
protected sites were also found in 
shallower water than at open coast- 
al sites — a difference that may have 
exposed them to higher ambient wa- 
ter temperature and may have ac- 
celerated their growth. Accelerated 
growth may in turn result in earlier 
maturation. Southern Tanner crabs 
probably settle over a wide range 
of depths, but shallow embayments 
(depths <50 m) may play a dispro- 
portionately large role in providing 
recruits to the adult population, 
due to accelerated crab growth and 
survival. 
Manuscript submitted 19 August 2014. 
Manuscript accepted 6 April 2015. 
Fish. Bull. 113:256-269 (2015). 
doi: 10.7755/FB. 113.3.3 
Online publication date: 30 April 2015. 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Fishery Bulletin 
.%» established 1881 ■<?. 
Spencer F. Baird 
First U.S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Depth distribution, habitat associations, 
and differential growth of newly settled 
southern Tanner crab {Chionoecetes bairdi) in 
embayments around Kodiak Island, Alaska 
Clifford H. Ryer (contact author ) 1 
William C. Long 2 
Mara L. Spencer 1 
Paul Iseri 1 
Email address for contact author: cliff.ryer@noaa.gov 
1 Fisheries Behavioral Ecology Program 
Alaska Fisheries Science Center 
National Marine Fisheries Service, NOAA 
2030 Marine Science Drive 
Newport, Oregon 97365 
2 Shellfish Assessment Program 
Alaska Fisheries Science Center 
National Marine Fisheries Service, NOAA 
301 Research Court 
Kodiak, Alaska 99615 
Nursery habitats for many crab and 
fish species are often found in waters 
considerably shallower than those 
frequented by the adult population. 
Three features commonly character- 
ize shallow-water juvenile nurseries. 
First, water temperatures are typical- 
ly higher there than in adult habitat, 
a difference that can facilitate rapid 
growth (Yamashita et al., 2001; Ryer 
et al., 2012). Because mortality typi- 
cally decreases with prey size (Sog- 
ard, 1997), rapid growth is a princi- 
pal determinant of survival to adult- 
hood. Second, shallow water usually 
is characterized by lower predation 
rates (Linehan et al., 2001; Mander- 
son et al., 2004; Baker and Sheaves, 
2007; Ryer et al., 2010). This feature 
follows from Heincke’s Law (sensu 
Cushing, 1975), which holds that the 
abundance of larger predatory fishes 
increases with depth. Lastly, shal- 
low-water nurseries often contain 
structurally complex habitat, such as 
rooted aquatic vegetation, drift algae, 
bivalve shell, cobble, terrestrial lit- 
ter, and polychaete tubes, which can 
mediate predator-prey interactions 
(Ryer et al., 2004; Long et ah, 2011, 
2013a) and, therefore, further reduce 
the risk of predation. 
Red king crab ( Paralithodes 
camtschaticus ), snow crab ( Chion- 
oecetes opilio), and southern Tanner 
crab ( Chionoecetes bairdi , hereafter 
“Tanner crab”) stocks in the North 
Pacific have experienced significant 
declines over the last 3 decades. 
The reasons for stock declines are 
little understood but are generally 
attributed to overfishing or climat- 
ic changes (Orensanz et al., 1998; 
Woodby et al., 2005). Stocks cur- 
rently are considered depressed or 
rebuilding, and closures have oc- 
curred throughout much of Alaska. 
Effective management of commercial 
species requires not only informa- 
tion on the current stock size but 
