352 
Habitat and diet overlap of 4 piscivorous fishes: 
variation on the inner continental shelf off 
New Jersey 
Email address for contact author: mark.wuenschel@noaa.gov 
1 Marine Field Station 
Rutgers University 
800 do 132 Great Bay Boulevard 
Tuckerton, New Jersey 08087-2004 
Present address for contact author: Northeast Fisheries Science Center 
National Marine Fisheries Service, NOAA 
166 Water St. 
Woods Hole, Massachusetts 02543 
2 New Jersey Department of Environmental Protection 
Nacote Creek Research Station 
P.O. Box 418 
Port Republic, New Jersey 08241 
Deceased 
Abstract— Piscivorous fishes, many 
of which are economically valuable, 
play an important role in marine 
ecosystems and have the potential to 
affect fish and invertebrate popula- 
tions at lower trophic levels. There- 
fore, a quantitative understanding of 
the foraging ecology of piscivores is 
needed for ecosystem-based fishery 
management plans to be successful. 
Abundance and stomach contents of 
seasonally co-occurring piscivores 
were examined to determine overlap 
in resource use for Summer Floun- 
der (Paralichthys dentatus; 206-670 
mm total length [TL] ), Weakfish 
(Cynoscion regalis\ 80-565 mm 
TL), Bluefish (Pomatomus saltatrix\ 
55-732 mm fork length [FL] ), and 
Striped Bass ( Morone saxatilis; 422- 
920 mm FL). We collected samples 
from monthly, fishery-independent 
trawl surveys conducted on the in- 
ner continental shelf (5-27 m) off 
New Jersey from June to October 
2005. Fish abundances and overlaps 
in diet and habitat varied over this 
study period. A wide range of fish 
and invertebrate prey was consumed 
by each species. Diet composition 
(determined from 1997 stomachs 
with identifiable contents) varied 
with ontogeny (size) and indicated 
limited overlap between most of the 
species size classes examined. Al- 
though many prey categories were 
shared by the piscivores examined, 
different temporal and spatial pat- 
terns in habitat use seemed to alle- 
viate potential competition for prey. 
Nevertheless, the degree of overlap 
in both fish distributions and diets 
increased severalfold in the fall as 
species left estuaries and migrated 
across and along the study area. 
Therefore, the transitional period of 
fall migration, when fish densities 
are higher than at other times of the 
year, may be critical for unraveling 
resource overlap for these seasonally 
migrant predators. 
Manuscript submitted 24 October 2012. 
Manuscript accepted 26 August 2013. 
Fish. Bull. 111:352-369. 
doi: 10.7755/FB.111.4.5 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necesarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Mark J. Wuenschel (contact author ) 1 
Kenneth W. Able 1 
James M. Vasslides 1 
Donald M. Byrne 2 * 
Predator species and their interac- 
tions with prey and other predator 
species play an important role in 
determination of the structure and 
function of ecosystems (Schmitz, 
2007; Braga et al., 2012) — an espe- 
cially important concern because 
populations of many predators have 
declined in abundance (Myers and 
Worm, 2003; Heithaus et ah, 2008). 
In marine ecosystems, piscivorous 
fishes have the potential to affect 
fish and invertebrate populations at 
lower trophic levels. In some cases, 
direct removals of prey resources by 
piscivorous fishes have been shown 
to rival or even exceed the remov- 
als by commercial fisheries (Buckel 
et al., 1999c; Overholtz et ah, 2000; 
Overholtz and Link, 2007). There- 
fore, fish trophic ecology is relevant 
to several aspects of fisheries man- 
agement (Link, 2002). With the gen- 
eral move toward multispecies and 
ecosystem-based approaches to fish- 
eries management, there is a need 
for more comprehensive information 
on food web structure, interspecific 
trophic interactions, and predator 
movements (Andrews and Harvey, 
2013). 
In temperate zones, many coastal 
marine fishes undergo large-scale 
seasonal and ontogenetic shifts in 
their spatial distribution. Examples 
from the east coast of the United 
States include species that migrate 
north to New England in summer 
and south to the Carolinas in winter 
(e.g., Striped Bass [Morone saxatilis ] 
and Bluefish [Pomatomus saltatrix ]) 
and species that move inshore in 
summer and offshore in winter (e.g., 
Summer Flounder [Paralichthys den- 
tatus] and Weakfish [Cynoscion rega- 
Z/s] ) (Able and Fahay, 2010). Further, 
many temperate, estuarine-depen- 
dent species in the Middle Atlantic 
Bight leave estuaries in the fall of 
their first year to avoid cold winter 
temperatures (Able and Fahay, 1998; 
2010). Many of these young-of-the- 
year (YOY) fishes are piscivorous 
and their egress from estuaries to 
coastal waters acts to concentrate 
them in time and space with other 
