224 
Fishery Bulletin 116(3-4) 
Month 
Figure 3 
Number of days of detection per month of tagged Atlantic sturgeon 
(Acipenser oxyrinchus oxyrinchus ) by acoustic receivers in the St. Johns 
River in Florida during 2014-2016. The number of days of detection (one 
detection per individual per day) were combined by month across all years 
of the study. 
Table 3 
Water temperatures and dissolved oxygen levels in the 
Altamaha and Satilla rivers in Georgia and the St. 
Johns River in Florida during June-July 2015. 
River 
Temperature ( 9 C) 
Dissolved 
oxygen (mg/L) 
Mean 
Standard 
deviation 
Mean 
Standard 
deviation 
Altamaha 
30.30 
0.73 
5.70 
0.47 
Satilla 
29.96 
0.67 
3.39 
0.61 
St. Johns 
29.50 
0.47 
4.70 
0.82 
for our study in the St. Johns River was far below the 
rates typically observed for sampling for studies in 
other rivers of the southeastern United States where 
populations have been documented (Table 4). Even in 
St. Marys River, which hosts the smallest known ex¬ 
tant population of Atlantic sturgeon (ASSRT, 2007; se¬ 
nior author and D. Peterson, unpubl. data), catch rates 
were an order of magnitude greater than those we ob¬ 
served in our study of the St. Johns River. In rivers 
with extant populations of Atlantic sturgeon, the meth¬ 
ods employed in our study generally produce dozens 
to hundreds of RRJ sturgeon annually (Schueller and 
Peterson, 2010; Bahr and Peterson, 2016; senior author 
and D. Peterson, unpubl. data). The complete absence 
of RRJs captured over the 2 consecutive summers of 
Table 4 
Concurrent sampling efforts in 2015 with the use of sim¬ 
ilar entanglement gear and the resulting catch of Atlan¬ 
tic sturgeon (Acipenser oxyrinchus oxyrinchus) measured 
as the number of individual fish caught per hour, in sev¬ 
eral rivers in the southeastern United States. 
River 
Soak 
time (h) 
of nets 
Number of 
individuals 
captured 
Catch 
(individuals/h) 
Ogeechee 
175 
154 
0.880 
Altamaha 
50 
76 
1.520 
Satilla 
176 
76 
0.432 
St. Marys 
122 
10 
0.082 
St. Johns 
149 
1 
0.007 
sampling in the St. Johns River indicates that a natal 
RRJ cohort was not likely present in either year of the 
study. 
The observed absence of RRJs during this study, 
though not conclusive, indicates that a viable popula¬ 
tion of Atlantic sturgeon is not currently present with¬ 
in the St. Johns River, as was suggested by Holder 
et al. 3 . Although a historical status of this population 
has never been confirmed, Gilbert (1992b) suggests 
that access to potential spawning habitat for a natal 
population likely was eliminated by the construction 
of the Kirkpatrick Dam in 1968. Still, we emphasize 
caution in designating Atlantic sturgeon as extirpated 
