148 
Fishery Bulletin 115(2) 
Table 2 
Categories of most important prey found in stomach contents of bluefish (Pomatomus saltatrix) and weakfish (Cynoscion 
regalis) captured during gill net sampling in 2007 in the Navesink River, New Jersey, expressed by season and age class as 
a percentage of total weight. 
Species 
Season 
Age class 
N 
Bluefish 
Summer 
Age-0 
73 
Bluefish 
Summer 
Age-14- 
18 
Bluefish 
Fall 
Age-0 
259 
Weakfish 
Spring 
Age-1+ 
70 
Weakfish 
Summer 
Age-0 
17 
Weakfish 
Summer 
Age-l4 
42 
Weakfish 
Fall 
Age-0 
127 
Weakfish 
Fall 
Age-l4 
22 
Amphipoda 
0.11 
0.00 
0.00 
0.02 
28.27 
0.00 
4.27 
0.00 
Mysidacea 
0.00 
0.00 
0.00 
41.00 
0.13 
0.01 
0.00 
0.00 
Caridea 
4.29 
0.77 
0.03 
56.67 
17.38 
3.56 
3.89 
0.00 
Brachyura 
15.83 
72.75 
0.29 
2.02 
0.00 
22.27 
2.64 
0.47 
Anchoa mitchilli 
1.41 
0.00 
0.57 
0.00 
4.54 
0.00 
0.65 
0.00 
Brevoortia tyrannus 
47.41 
1.18 
94.67 
0.00 
40.99 
32.04 
83.39 
95.85 
Cynoscion regalis 
5.02 
0.00 
0.00 
0.00 
0.00 
6.70 
0.00 
0.00 
Menidia menidia 
8.31 
2.51 
1.34 
0.00 
0.00 
3.86 
1.04 
0.00 
Pomatomus saltatrix 
0.00 
12.75 
0.00 
0.00 
0.00 
2.55 
0.00 
0.00 
Fish, unid. and other organisms 
17.62 
10.04 
3.09 
0.30 
8.69 
29.01 
4.13 
3.72 
that season they were captured largely in the channel. 
Age-0 and age-l-i- weakfish were more abundant at the 
channel station than at the front station in all seasons. 
Overall, the most important prey by percent weight 
was Atlantic menhaden (Table 2). By cluster analysis 
(at 30% similarity), the greatest differences in diet re¬ 
sulted with season and age class, and with predator 
species of lesser importance. In spring, age-l+ weak¬ 
fish consumed mainly sand shrimp (Crangon septem- 
spinosa) and mysids (Neomysis americana). In summer, 
age-0 bluefish, median length 150 mm TL, ate age-0 
Atlantic menhaden, species of the infraorder Brachy- 
ura, Atlantic silverside (Menidia menidia), age-0 
weakfish, and other fish species. In that season, age-1 
bluefish ate species of Brachyura (mainly blue crabs 
[Callinectes sapidus]) and smaller bluefish. In sum¬ 
mer, weakfish consumed Atlantic menhaden, other fish 
species, and blue crabs, and the age-0 weakfish also 
consumed amphipods and species of the infraorder Ca- 
ridea (sand shrimp and grass shrimp [Palaemonetes 
spp.]). The other fish species in both seasons included 
winter flounder (Pleuronectes americanus) and striped 
searobin {Prionotus evolans). In fall, Atlantic menha¬ 
den constituted 91.9% of the stomach contents of all 
predators at both stations. 
Differences in stomach contents between stations A 
(front) and B (channel) were found only for bluefish in 
summer. At that time, bluefish consumed more crabs 
at station B than at station A and more Atlantic men¬ 
haden at station A than at station B (Mann-Whitney 
tests: P<0.01). 
Potential prey fish were captured in the fine mesh 
panels of the gill nets at both Stations A and B (Fig. 
3). Summer was the only season in which the catch at 
the 2 stations was different. At that time, significantly 
more Atlantic silverside were caught at the front than 
at the channel, and significantly more Atlantic men¬ 
haden were captured at the channel than at the front 
(Mann-Whitney tests: P<0.01). In summer, age-0 blue¬ 
fish and weakfish were also potential prey, the former 
at the front and the latter at the channel. In fall, near¬ 
ly all the potential prey collected at both stations were 
age-0 Atlantic menhaden. Although bay anchovy were 
common in predator diets, they were rarely collected in 
the gear during sampling. 
Telemetry 
Home ranges for ultrasonically tracked striped bass, 
bluefish, and weakfish in the Navesink River in 2006 
and 2007 averaged 73-133 in area, depending on 
species (Table 3). There was great variation among in¬ 
dividuals of each taxon. Striped bass had the smallest 
home ranges by area. Home ranges of age“l+ bluefish 
were larger than those of weakfish and age-0 bluefish, 
although not significantly different. 
From 2006 through 2007, 89 tracked fish met the 
criteria for mapping, and the centers of their home 
ranges were located mainly in one or more of 4 defined 
reaches of the estuary (Figs. 4 and 5). Detections were 
relatively few in number at river kilometers 3-5 and 
7-8. 
Reach 1 Shoals and islands in the lower river near 
the confluence of the Navesink and Shrews¬ 
bury rivers (river kilometers 1-3). 
Reach 2 Channel on both sides of the Oceanic Bridge 
(river kilometers 5-7). 
Reach 3 From McClees Creek to the channels off 
Guyon Point, including Station B (river kilo¬ 
meters 8-10). 
Reach 4 Upper river, from the Red Bank basin to 
Jones Point, including the salinity front and 
Station A (river kilometers 10.0-11.5). 
