Stehlik et al.: Distribution of 3 predatory fish at a salinity front in a small estuary 
149 
A B C D 
n-214 n-133 «=258 n=256 
Figure 3 
Most abundant forage fish (<150 mm) caught by gill nets in the Navesink River in New Jersey 
in 2007 and the total number of fish captured per season: (A) spring catch, (B) summer catch 
from station A at salinity front, (C) summer catch from station B at channel, and (D) fall 
catch. Forage fish species include the bay anchovy {Anchoa mitchilli, [Ancmit in the key]), 
Atlantic menhaden (Brevoortia tyrannus, [Bretyr]), weakfish {Cynoscion regalis, [Cynreg]), At¬ 
lantic silverside (Menidia menidia, [Menmen]), and bluefish (Pomatomus saltatrix, [Pomsal]). 
I I Ancmit 
Bretyr 
FVI Cynreg 
12Z! Menmen 
Pomsal 
Table 3 
Species, age class, year, number of fish, length range of fish (TL), mean home range (m^), stan¬ 
dard deviation (SD), and reaches (1-4) of the Navesink River, New Jersey, most frequented 
by striped bass (Morone saxatilis), bluefish {Pomatomus saltatrix), and weakfish (Cynoscion 
regalis) tagged ultrasonically in 2006 and 2007. 
Species and 
age class 
Year 
Number 
of fish 
Length 
range(TL) 
Mean home 
range (m^) 
SD 
Reaches 
Striped bass 
2006 
17 
359-597 
81.7 
56.97 
1, 2,3,4 
Striped bass 
2007 
3 
445-510 
72.7 
39.88 
1,3,4 
Age-0 bluefish 
2006 
9 
194-270 
101.4 
76.56 
3,4 
Age-0 bluefish 
2007 
11 
222-275 
101.9 
68.55 
3,4 
Age-1+ bluefish 
2006 
6 
320-345 
132.9 
85.31 
2,3,4 
Age-1+ bluefish 
2007 
14 
310-690 
126.7 
67.20 
1,2, 3,4 
Weakfish 
2006 
8 
224-535 
95.1 
86.78 
2,3 
Weakfish 
2007 
21 
304-480 
101.1 
67.29 
2,3 
Home ranges of striped bass were located in reaches 
3 and 4, with a few detections in reach 1 near the river 
mouth, in 2006 and 2007. The home ranges of weak¬ 
fish (all but 2 fish were age 1+) were centered in the 
channels in reaches 2 and 3, at river kilometers 5-10, 
in both years. For bluefish, ontogenetic differences in 
home ranges were observed in both years. The home 
ranges of age-l+ bluefish were more extensive, from 
reaches 2 through 4, at river kilometers 4-11. The 
home ranges of age-0 bluefish were centered mostly in 
reaches 3 and 4, at river kilometers 8-12, across the 
front and upriver to the Red Bank basin and Swim¬ 
ming River. Detections of bluefish were not as specific 
to channel habitats as were detections of weakfish. 
Some fish shifted from a primary home range to a 
secondary home range during their period of residence. 
For example (Fig. 6), an age-l-i- bluefish released on 
year day 122 was detected in reaches 3 to 4 at receiv¬ 
ers located from the Red Bank basin to the Oceanic 
Bridge. Then, beginning on year day 142, it v/as de¬ 
tected downriver in reaches 1 and 2, at receivers from 
Claypit Creek to Barley Point, until it passed the last 
receiver and out of the river on year day 152. 
The signals from some fish ceased and were detect¬ 
ed again later in the season. Some striped bass were 
tagged in spring, subsequently detected in reach 1 , 
apparently exited the river, and were detected again 
as they returned in fall. Some striped bass and age- 
14- bluefish were detected at the farthest west receiver, 
disappeared, and then were detected again, apparently 
having made excursions into Swimming River. 
Discussion 
Salinity fronts, prey fields, and diets 
We hypothesized that striped bass, bluefish, and weak¬ 
fish would be found most often in the Navesink River in 
the vicinity of the main salinity transition front in the 
