382 
Abstract — Pacific cod (Gadus macro- 
cephalus ) is an important component 
of fisheries and food webs in the North 
Pacific Ocean and Bering Sea. How- 
ever, vital rates of early life stages of 
this species have yet to be described 
in detail. We determined the ther- 
mal sensitivity of growth rates of 
embryos, preflexion and postflexion 
larvae, and postsettlement juveniles. 
Growth rates (length and mass) at 
each ontogenetic stage were measured 
in three replicate tanks at four to five 
temperatures. Nonlinear regression 
was used to obtain parameters for 
independent stage-specific growth 
functions and a unified size- and tem- 
perature-dependent growth function. 
Specific growth rates increased with 
temperature at all stages and gener- 
ally decreased with increases in body 
size. However, these analyses revealed 
a departure from a strict size-based 
allometry in growth patterns, as 
reduced growth rates were observed 
among preflexion larvae: the reduc- 
tion in specific growth rate between 
embryos and free-swimming larvae 
was greater than expected based on 
body size differences. Growth reduc- 
tions in the preflexion larvae appear 
to be associated with increased meta- 
bolic rates and the transition from 
endogenous to exogenous feeding. In 
future studies, experiments should 
be integrated across life transitions 
to more clearly define intrinsic onto- 
genetic and size-dependent growth 
patterns because these are critical for 
evaluations of spatial and temporal 
variation in habitat quality. 
Manuscript submitted 12 March 2010. 
Manuscript accepted 8 June 2010. 
Fish. Bull. 108:382-392 (2010). 
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. 
Ontogenetic patterns and 
temperature-dependent growth rates 
in early life stages of Pacific cod 
( Gadus macrocephalus ) 
Thomas P. Hurst (contact author ) 1 
Benjamin J. Laurel 1 
Lorenzo Ciannelli 2 
Email address for contact author: thomas.hurst@noaa.gov 
1 Fisheries Behavioral Ecology Program 
Resource Assessment and Conservation Engineering Division 
Alaska Fisheries Science Center, 
National Marine Fisheries Service, NOAA 
Hatfield Marine Science Center 
Newport, Oregon 97365 
2 College of Atmospheric and Oceanographic Sciences 
Oregon State University 
Corvallis, Oregon 97331 
Fluctuations in the distribution and 
abundance of marine species are 
highly influenced by climate-driven 
changes in ocean conditions (Perry et 
al., 2005). In the Gulf of Alaska and 
Bering Sea, oceanographic regimes 
linked to climate conditions (Hollowed 
et al., 2001; Peterson and Schwing, 
2003) occur across a variety of time 
scales, from seasonal to multidecadal 
(Hunt and Stabeno, 2002). These cli- 
mate cycles have been linked to major 
shifts in the composition of valuable 
groundfish communities (Anderson 
and Piatt, 1999). Imposed upon this 
variation is the potential for longer- 
term climate changes, such as the 
warming of surface waters and loss of 
sea ice (e.g., Hunt et al., 2002). Such 
warming trends have already been 
observed in the Gulf of Alaska (Royer 
and Grosch, 2006) and Bering Sea 
(Stabeno et al., 2007). The response 
of individual populations and entire 
communities to environmental forcing 
depends upon the physiological and 
behavioral traits of individual spe- 
cies and the cumulative set of trophic 
interactions between species (Freitas 
et al., 2007; Yatsu et al., 2008; Hurst 
et al., 2010). 
Spatial and temporal variation in 
temperature and prey availability 
are considered to be primary driv- 
ers of growth and survival in early 
life stages of fishes and their influ- 
ence on recruitment has been central 
to various generalized models of re- 
cruitment (see review by Cowen and 
Shaw, 2002). The oscillating control 
hypothesis (OCH) states that popu- 
lation production of groundfish in 
the Bering Sea is linked to climate- 
driven patterns of prey production: 
cold winters with extensive sea ice 
result in early, low-density blooms 
in cold water, resulting in reduced 
survival of larvae (Hunt and Sta- 
beno, 2002). Evaluation of the OCH 
and predicting potential responses 
to future aspects of climate change 
require detailed information on the 
temperature-dependent vital rates of 
early life stages of fish (Kristiansen 
et al., 2007; Hollowed et al., 2009; 
Rijnsdorp et al., 2009). 
Pacific cod (Gadus macrocephalus) 
is a widespread marine species on 
continental shelves throughout the 
eastern and western North Pacific 
and Bering Sea. They are an im- 
portant component of North Pacific 
and Bering Sea fisheries and food 
webs. In recent years, U.S. land- 
ings of Pacific cod trail only those 
of Alaska walleye pollock (Theragra 
chalcogramma ) and Atlantic and gulf 
menhaden (Brevoortia tyrannus and 
B. patronus) (NMFS, 2008). Between 
2002 and 2006, U.S. landings of Pa- 
