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Fishery Bulletin 108(1 ) 
a multiple regression model based on growth, mortal- 
ity, and maximum length. Aguado-Gimenez and Gar- 
cia-Garcia (2005) found that large (mean weight=237 
kg) bluefin tuna held under fattening conditions con- 
sumed 1.56% body weight per day. Andreas Walli 5 
estimated a DR of 1.1% [±0.3%] body mass per day 
based on heat incremented feeding of archival-tagged 
bluefin tuna tracked throughout the western Atlantic. 
Although the mean DR estimate (2.03% ±0.59%) from 
the current study is somewhat greater than that of 
previous studies, our estimate is potentially negatively 
biased for two reasons. First, we used the longest time 
5 Walli, Andreas. 2006. Unpubl. data. Stanford Univ., Stan- 
ford, CA 94305. 
between periods of peak stomach fullness and empty 
stomachs. Increasing the time required for gastric 
emptying effectively decreases the estimate of the 
amount of food consumed on a daily basis. Second, 
stomach fullness could be decreased by regurgitation 
during hook-and-line capture and digestion could be 
continued after death. 
Predatory impact 
An understanding of predator-prey interactions is nec- 
essary for ecosystem-based assessment models. Bluefish, 
striped bass, weakfish, and fishermen are considered 
the dominant predators of Atlantic menhaden in cur- 
rent multispecies assessment models (NEFSC 2 ). The 
assumption that bluefin tuna are not a domi- 
nant predator of Atlantic menhaden along 
the U.S. East Coast appears correct given the 
small amount of Atlantic menhaden consumed 
by bluefin tuna in relation to other Atlantic 
menhaden predators. However, the goal of 
ICCAT is to rebuild the biomass of western 
Atlantic bluefin tuna population to its 1975 
level by 2018 (ICCAT, 2007). If the population 
is rebuilt, our estimates of consumption indi- 
cate that bluefin tuna should be considered 
in future multispecies modeling efforts where 
Atlantic menhaden are a focal prey. Similarly, 
Overholtz (2006) suggested that a recovery of 
the western bluefin tuna stock would make 
bluefin tuna a dominant predator of Atlantic 
herring in the Georges Bank region. 
Similar to results for bluefish (Buckel et 
al., 1999; NEFSC 2 ), striped bass (Hartman, 
2003; Uphoff, 2003; NEFSC, 2006 2 ), and 
weakfish (NEFSC 2 ), our estimates of Atlan- 
tic menhaden consumption by bluefin tuna 
were lower than any of the annual coastwide 
estimates of Atlantic menhaden commercial 
harvests during the last 25 years 1 . However, 
with continued attempts at rebuilding popu- 
lations of bluefin tuna, bluefish, striped bass, 
and weakfish stocks, predation mortality may 
become a more important component of the 
overall mortality rate of Atlantic menhaden. 
For future modeling efforts, it is important 
to note that sizes of Atlantic menhaden 
consumed by bluefin tuna were larger than 
previously reported sizes of Atlantic men- 
haden prey found in bluefish, striped bass, 
and weakfish (Butler, 2007). Additionally, 
competition for Atlantic menhaden resources 
during winter may be most important off of 
NC during winter, and future efforts to in- 
vestigate this will require information on 
the spatial distribution of these predators 
during winter. 
There were several sources of uncertainty 
in our analysis of predatory demand. First, 
our study was dependent on the commer- 
