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Fishery Bulletin 111(4) 
er depths (from 27 to >193 m) (Able and Fahay, 2010), 
with similar sizes present during our 5-month study 
on the inner continental shelf. Weakfish in our study 
occurred primarily inshore in shallow strata. Their 
abundance increased through the summer because of 
the appearance of YOY fish, and they dominated the 
catch by October — a trend also observed in composite 
collections over time on the deeper continental shelf 
(Able and Fahay, 2010). 
The size structure of Bluefish was similarly variable 
with multiple YOY cohorts appearing during summer 
and eventually dominating the proportion of catch by 
October. Bluefish were concentrated at inshore, shallow 
stations, as had been documented previously (Able et 
ah, 2003; Wiedenmann and Essington, 2006; Wuenschel 
et al., 2012). In October, the distribution of Bluefish 
was more uniform with depth, and they appeared to 
utilize a greater portion of the inner continental shelf 
during the period of southward migration, as was evi- 
dent from other composite sampling at similar and 
deeper depths (Able and Fahay, 2010). 
Bluefish and Weakfish distributions indicated a high 
degree of similarity in their use of the inshore shelf 
during the summer months. In contrast, the distribu- 
tion of Striped Bass was limited to the northernmost 
stations during summer. Like Bluefish, Striped Bass 
were more abundant throughout the study area during 
their fall migration (October). The limited collections of 
Striped Bass, coupled with a priority to tag and release 
them during certain months, restricted our ability to 
describe Striped Bass diets. Nevertheless, Striped Bass 
showed little overlap in habitat use with the other 
predators studied. 
The species-level distributions and monthly size fre- 
quencies tended to overestimate overlap because dif- 
ferent sizes may have occupied different locations in 
a given month. When viewed at the size-class level, 
spatial (habitat) overlap was rarely above 0.6. Simi- 
larly, assessment of diet overlap at the species level 
(i.e. , combining size classes and ignoring ontogenetic 
shifts in diet) would likely increase perceived overlap. 
For example, large and medium Summer Flounder 
diet overlap was moderate (a -0.2-0. 5) and overlap 
between medium and small sizes was similarly vari- 
able (a -0.3-0. 6), but overlap between large and small 
Summer Flounder was much lower (a -0.2-0. 3). This 
result supports the interpretation of gradual onto- 
genetic changes in diet and some similarity between 
adjacent size classes. Use of a single size group for 
Striped Bass because of limited sample sizes prevented 
the exploration of ontogenetic shifts for this species, 
which were significant in one study (Smith and Link, 
2010) but not another (Walter et al., 2003). Regardless 
of potential ontogenetic differences, their extensive 
use of estuaries in New Jersey and throughout their 
range during many seasons (Able and Fahay, 2010) 
probably also contributes to the limited co-occurrence 
of this species with the other species size classes 
studied. 
Unidentified fish remains were large components 
of the diet for many of the species size classes in our 
study — a common problem encountered in the analysis 
of stomach contents (Garrison and Link, 2000a; 2000b). 
The presence of large portions of UID fishes serves 
to increase the overlap in diet and decrease the num- 
ber of distinct clusters from the groups analyzed. As- 
suming that identifiable and unidentifiable prey oc- 
cur in similar relative proportions, we consider the 
separation of distinct groupings in our analysis to be 
conservative. Where diets between species size classes 
showed little overlap, we can conclude diets were in- 
deed different. 
The diets of Summer Flounder, Weakfish, Bluefish, 
and Striped Bass on the inner continental shelf of 
New Jersey during summer varied month to month — 
an observation that could not be obtained from previ- 
ous studies conducted in the region across a greater 
portion of the shelf region over multiple years (Gar- 
rison and Link, 2000b; Link et ah, 2002; Walter et al., 
2003; Buckel et al., 2009; Smith and Link, 2010). The 
finer scale in our study accounts for the slightly dif- 
ferent patterns of similarity among Summer Flounder, 
Weakfish, Bluefish, and Striped Bass diets in compari- 
son with results that had been reported previously for 
the shelf ecosystem of the northeastern United States 
(Garrison and Link, 2000b). Although the size classes 
differed slightly, this previous study reported Summer 
Flounder (21-70 cm) and Bluefish (>31 cm) in a pisci- 
vore guild distinct from small Bluefish (10-30 cm) and 
Weakfish (10-50 cm). 
On a much finer spatial scale, we observed greater 
overlap in diets, which varied through time, between 
Summer Flounder and Weakfish, particularly for the 
small and medium size classes. This similarity was 
driven by large amounts of mysids and other crusta- 
ceans in the diet. Both Summer Flounder and Weakfish 
incorporated more fishes and squids in their diet as 
they increased in size. The early onset of piscivory by 
Bluefish separated them from the smaller size classes 
of Summer Flounder and Weakfish. Together, these dif- 
ferences relative to earlier studies point out the ad- 
vantages of the finer temporal, spatial, and size-class 
scales used in this study. 
Of the 4 predators analyzed from the Mid-Atlantic 
region in our study, only Weakfish were consumed in 
appreciable numbers by the other species. Weakfish 
were consumed by small Summer Flounder (16.5%) in 
July and small Bluefish (9.5%) in August, and an appre- 
ciable amount of cannibalism by medium-size Weakfish 
(23.5%) was observed in August. In October, large Blue- 
fish and Summer Flounder fed extensively on Weakfish 
(25.2-26.7%), with medium and small Summer Floun- 
der and Striped Bass also consuming Weakfish but in 
lesser proportions. Similarly, in Long Island bays, YOY 
Bluefish and Summer Flounder consumed Weakfish 
(7.5% and 3.0% by weight, respectively); however, data 
were reported across sizes and seasons (spring, sum- 
mer, and fall), and Weakfish diet was not investigated 
