Schmitt et al.: Modeling the predation dynamics of invasive Ictalurus furcatus in Chesapeake Bay 
287 
This study had limitations. First, winter diet informa¬ 
tion was not included in our modeling exercises because 
it was not collected in a randomized manner. This omis¬ 
sion is problematic because blue catfish consume blue 
crab during winter, although the spatiotemporal extent 
of these data is limited (Schmitt et al., 2019). Second, we 
had limited success capturing blue catfish when using 
low-frequency electrofishing in brackish areas (S P >10), 
although blue catfish have been captured in S P levels as 
high as 21.5 (Fabrizio et al., 2018). Our limited success in 
these locations is simply an artifact of low-frequency elec¬ 
trofishing, which becomes ineffective at higher salinities 
(Bringolf et al., 2005). Predation on blue crab increases 
with salinity; therefore, we may be underestimating 
predation by blue catfish on this commercially valuable 
species. Future studies in Chesapeake Bay should focus 
on the diet of blue catfish during winter, particularly in 
brackish areas with S P levels >10. 
This study focused on invasive blue catfish in Chesa¬ 
peake Bay; however, the development of similar models 
could be useful for other invasive species, especially if 
the goal is to minimize predation for specific organisms. 
Although it does not necessarily result in population-level 
effects (Ney, 1990), predation has been identified as a 
major driver in the decline of native species richness at the 
global scale (Mollot et al., 2017). Predation is particularly 
dangerous for depleted biota because it can impede popu¬ 
lation recovery and even drive organisms to extinction. No 
evidence conclusively indicates that blue catfish are driv¬ 
ing alosines to extinction (e.g., some signs of recovery have 
been observed for populations of American shad in the 
Rappahannock River), yet other invasive predators have 
driven prey to extinction (Spencer et al., 2016). In these 
cases, the best approach may be to determine the factors 
that lead to greater predation on specific biota. This infor¬ 
mation could also provide guidance for additional harvest 
of the invader (Schmitt et al., 2017). Models of predation 
for depleted species could be especially useful for control of 
invasive predators in large, open systems where eradica¬ 
tion is not a viable option (Franssen et al., 2014; Thresher 
et al., 2014). In these circumstances, targeted harvest may 
be the best approach, with the goal of “suppress [ing] inva¬ 
sive populations below levels predicted to cause undesir¬ 
able ecological change” (Green et al., 2014). 
Acknowledgments 
We thank C. Hilling, B. Peoples, J. Emmel, Z. Moran, 
J. Woodward, A. Mosely, H. Kim, H. Lee, B. Greenlee, 
J. Odenkirk, R. Willis, K. Johnson, A. Weaver, Y. Jiao, and 
S. Smith for their assistance over the course of the study. 
We thank the anonymous reviewers whose comments 
resulted in a better manuscript. Data collection was sup¬ 
ported by the Virginia Department of Game and Inland 
Fisheries through a Sport Fish Restoration Grant from 
the U.S. Fish and Wildlife Service (contract #2012-13705), 
and the senior author was partially supported through a 
fellowship from Virginia Sea Grant (R/71856A). 
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