Wilson et al : Regional variation in the feeding cycle of |uvenile Theragra chalcogramma 
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160 o W 158°W 156°W 154”W 152°W 
Figure 1 
Sites where juvenile walleye pollock ( Theragra chalcogramma ) were collected 
with trawl nets in the Gulf of Alaska from August 2000 to September 2001. 
Delineation of season and geographic region follow Buchheister et al. (2006) (see 
Table 1 for specific sampling dates). Arrows in inset represent the predominant 
currents in Alaskan waters (Reed and Schumacher, 1986). 
a persistent along-shore shift in body length of age-0 
juveniles occurs at about Sutwik Island and relatively 
large juveniles are found northeastward in the Kodiak 
Island region (Wilson, 2000). In addition to larger body 
lengths, these juveniles also have greater length-specific 
weights and are more energy dense than fish from other 
regions, particularly in late summer and winter (Bu- 
chheister et al. 2006). The underlying cause remains 
unproven but likely involves some aspect of feeding 
ecology. For example, juveniles collected near Kodiak 
Island during late summer had a euphausiid-rich diet 
(Merati and Brodeur, 1996; Wilson et al., 2005; Wilson 
et al., 2009) and faster growth (Bailey et al., 1996) 
than individuals collected in the Semidi Bank vicinity. 
There is currently insufficient evidence in the literature 
to evaluate the role of food habits in determining re- 
gional and cyclical variation in growth, body condition, 
and perhaps survival of juvenile walleye pollock in the 
western GOA. 
Our objective was to examine the food habits of juve- 
nile walleye pollock for evidence of an annual cycle and 
to elucidate how these food habits may vary regionally 
in relation to previously observed geographic variation 
in juvenile body condition and growth rate. The focus 
on one year class simply reflects sample availability. 
Samples of the 2000 year class were available from 
directed sampling during late summer 2000 (age-0 ju- 
veniles) and during late summer 2001 (age-1 juveniles). 
An additional set of samples was available from oppor- 
tunistic sampling. Examining fish from these sample 
sets enabled us to provide new insight and formulate 
hypotheses about annual periodicity and regional varia- 
tion in the food habits of juvenile walleye pollock. Previ- 
ously, all or a subset of these same samples were used 
to examine body condition (Buchheister et al., 2006) 
and growth rates of juvenile walleye pollock (Mazur et 
al., 2007; Wilson et al., 2011). We conducted a modeling 
exercise to integrate these previous findings with our 
observations on food habits and explore the implication 
of these results on juvenile walleye pollock growth rate. 
Materials and methods 
Sample collection 
Juvenile walleye pollock were collected from 124 trawl 
catches in the western GOA during August 2000 to Sep- 
tember 2001 during nine research cruises conducted by 
the National Marine Fisheries Service (NMFS). Samples 
were grouped according to collection location and date 
according to the method of Buchheister et al. (2006). 
There were three geographic regions (Kodiak, Semidi, 
and Shumagin) and four seasons (late summer 2000 
[LSumOO], winter 2001 [WinOl], summer 2001 [SumOl], 
and late summer 2001 [LSumOl]) (Table 1, Fig. 1). The 
geographic divisions within the experimental study area 
somewhat arbitrarily distinguished alongshore regions 
