366 
Fishery Bulletin 111(4) 
of 4 piscivores on the inner continental shelf off New 
Jersey from summer through fall. It does not consider 
these parameters on adjacent estuaries where these 
species can also be abundant (Able and Fahay, 2010). 
For example, Striped Bass are known to use estuar- 
ies in the region during the summer (Tupper and Able, 
2000; Able and Grothues, 2007; Ferry and Mather, 
2012). The same is true for Bluefish (Grothues and 
Able, 2007; Sagarese et al., 2011), Summer Flounder 
(Sackett et al., 2007; 2008; Sagarese et al., 2011), and 
Weakfish (Taylor, 1987; Turnure 2010). Therefore, our 
findings from the inner shelf should be viewed with 
this qualification in mind. As an example, the diets de- 
scribed here for inshore waters revealed differences in 
diets, compared with diets observed in studies carried 
out within estuaries (Gartland et al., 2006; Latour et 
al., 2008; Sagarese et al., 2011). 
Although not necessarily unexpected given differ- 
ences in prey availability between estuarine and ocean 
habitats, these differences in diets underscore the need 
to incorporate into ecosystem models both distribution 
and diet information from the inner shelf and adja- 
cent estuaries because of connectivity between them, 
especially over seasonal scales (Able, 2005). These 
data have typically been lacking. Many prey categories 
were shared by the piscivores examined in our study 
on the inner continental shelf, but different patterns 
in habitat use (in time and space) seemed to allevi- 
ate overlap between these predators for prey. However, 
overlaps in fish distributions and diets increased dur- 
ing fall as species left estuaries and underwent coastal 
migrations. Therefore, the information on spatial dis- 
tributions and food habits reported here at finer spatial 
and temporal scales, compared to results from previous 
studies, complements and provides a critical link be- 
tween what is known about these mobile, seasonally 
migratory predators within estuaries and about these 
same piscivores across larger geographic scales (e.g., 
the northeastern shelf of the United States). It is rea- 
sonable to ask whether diet overlap may continue to 
increase during winter when many of these predators 
are concentrated farther south and likely co-occur in 
thermal refuges in the South Atlantic Bight. 
Conclusions 
Results from this study, at finer temporal, spatial, and 
size-class scales than have been attempted typically 
in other studies, indicate that overlap in distribution 
on the inner continental shelf for the 4 piscivores ex- 
amined was not uniform through time and that they 
had moderate levels of overlap in diet. The exception 
was observed in the fall, when many of these species 
became concentrated as both larger individuals and 
smaller YOY fishes left estuaries, gathered with other 
individuals on the inner shelf, and began their south- 
ward migration as temperatures cooled. Given the high 
seasonal variability in water temperature and produc- 
tivity in the system studied and the migratory nature 
of the species investigated, it is not surprising that 
habitat use and species interactions were variable. 
Our understanding of species interactions on the 
inner continental shelf has been limited, in the past, 
by the gap between sampling programs within estuar- 
ies and bays and programs occurring farther offshore. 
The intensive monthly sampling of this study on the 
inner continental shelf revealed the dynamic nature of 
habitat and diet overlap for Summer Flounder, Weak- 
fish, Bluefish, and Striped Bass. The use of inner shelf 
resources by these 4 important species had previously 
been poorly defined. The limited degree of resource 
overlap in summer and the increasing overlap in fall 
for the 4 piscivores indicate that this period of change- 
able overlap may be important for the population dy- 
namics of these species and that information about it 
should be incorporated into not only species-specific 
models of population dynamics but also broader eco- 
system-level models. 
| 
Acknowledgments 
This study was funded through a grant from the col- 
laborative Bluefish/Striped Bass Dynamics Research 
Program of Rutgers University and the National Ma- 
rine Fisheries Service. The authors thank New Jersey 
Department of Environmental Protection personnel (L. 
Barry, A. Mazzarella and S. Reap), the staff at the Rut- 
gers University Marine Field Station and Captain S. 
Cluett and crew of the RV Seawolf for assistance. The 
following individuals provided field and laboratory as- 
sistance: R. Nichols, M. Greaney, J. Conwell, J. Lamo- 
naca, J. Eppenstiener, and J. Bunkiewicz. B. Smith, S. 
Rowe, and anonymous reviewers provided constructive 
comments on the manuscript. We are grateful to all of 
the above. This article is contribution no. 2013-3 from 
the Institute of Marine and Coastal Sciences, Rutgers 
University. 
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