552 
Fishery Bulletin 99(4) 
lished estimates of maximum consumption measured in 
laboratory experiments (Hartman and Brandt, 1995b). 
Their estimates of maximum consumption (for a 10-g fish) 
increased from 0.45%bw/day at 1°C to 7.10%bw/day at 
10°C. The highest percentages of predicted maximum con- 
sumption achieved by YOY striped bass in the Hudson 
River occurred on 6 January 1994 (25.8%), and on three 
dates in early winter 1995 (15.5-18.0%). On other dates 
consumption was generally below 10% of maximum esti- 
mated from the Hartman and Brandt (1995b) model. 
Bull et al. (1996) developed a model of consumption 
for overwintering juvenile Atlantic salmon in which appe- 
tite was related to anticipated metabolic requirements. To 
minimize the risks of starvation and predation associated 
with foraging, they predicted that appetite of overwinter- 
ing fish should be highest in early winter (when future 
metabolic needs are greatest) or when internal energy re- 
serves are low. Our results suggest that a similar model 
might be appropriate for overwintering striped bass. Gut 
fullness levels of YOY striped bass were related to level 
of lipid reserves at the individual level (Fig. 3). Although 
some fish had empty stomachs at all energy levels, the 
highest observed gut fullnesses were found in fish with 
low lipid levels. This finding suggests that overwintering 
striped bass increase feeding activity when energy re- 
serves become depleted. Such feeding patterns have been 
documented in laboratory experiments with Atlantic salm- 
on (Metcalfe and Thorpe, 1992) and striped bass (Hurst 
and Conover, 2001) but have not previously been observed 
among fish feeding in the wild. 
At the population level, we observed a negative relation- 
ship between mean gut fullness and date; gut fullnesses 
were higher in early winter than late winter (Fig. 4). This 
pattern was predicted in the Atlantic salmon model (Bull et 
al., 1996) but could also be due to external factors such as 
depleted food resources at the end of winter. Benthic prey 
production is likely reduced by low winter temperatures, 
and standing stocks may become depleted as winter pro- 
gresses. Further work is required to determine fully the 
causes and implications of reduced gut fullnesses observed 
in later winter. Reduced feeding in late winter may reflect 
the availability of sufficient energetic reserves and suggests 
that starvation is unlikely. Conversely, reduced feeding due 
to depressed prey availability in late winter would indicate 
a strong potential for winter starvation. The role of starva- 
tion in winter mortality will depend greatly on determining 
if variable feeding patterns among years are due to inter- 
nally controlled variations in feeding motivation or environ- 
mentally imposed constraints on prey availability. 
Acknowledgments 
We thank J. Powers for assistance with stomach content 
and lipid analyses. Significant assistance with field collec- 
tions was provided by the New York Power Authority and 
the crews of the RV Pannaway and the RV Heather M II. S. 
Munch provided advice on data analysis. R. Cowen, R. Cer- 
rato, D. Lonsdale, E. Houde, and two anonymous reviewers 
provided valuable comments on this manuscript. This work 
was funded by a graduate fellowship in population biology 
from the Electric Power Research Institute (T.P. Hurst) 
and by research grants from the Hudson River Foundation 
for Science and Environmental Research and the National 
Science Foundation (OCE9530209 to D.O. Conover). 
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