243 
National Marine 
Fisheries Service 
NOAA 
Fishery Bulletin 
@ established in 1881 << 
Spencer F. Baird fe ith 
First U.S. Commissioner ye Py 
of Fisheries and founder § 
of Fishery Bulletin 
Abstract—The Gulf sturgeon (Acip- 
enser oxyrinchus desotoi) is an anad- 
romous fish found in drainages of the 
Gulf coast from Louisiana to Florida 
and is federally listed as threatened 
under the Endangered Species Act. 
Estimates of abundance of adult Gulf 
sturgeon from several studies have 
been reported, but direct quantifica- 
tion of juvenile abundance has not been 
attempted—although such information 
regarding annual recruitment and juve- 
nile population trends is critical. Our 
objectives were to quantify recruitment 
of Gulf sturgeon in the Apalachicola 
River in Florida by estimating age-1 
juvenile abundance and to investigate 
their survival. During May—August in 
2013-2018, we used entanglement gear 
to conduct a mark-recapture assess- 
ment of juvenile Gulf sturgeon. Using 
Huggins closed population models, we 
estimated that the Apalachicola River 
produces 28-210 age-1 juveniles annu- 
ally (mean: 70 individuals [standard 
deviation 69.4]). Acoustic telemetry 
data collected from a subset of age-1 
fish indicate that the study area was 
closed during sampling. We conserva- 
tively estimated overwinter survival on 
the basis of detections and recapture of 
age-2+ fish acoustically tagged at age 
1. Survival varied among years from 
33% to 90%. These results indicate that 
direct estimates of recruitment of Gulf 
sturgeon to age 1 are feasible, but it is 
difficult to determine whether this pop- 
ulation is recruitment limited without 
similar data for other populations of 
Gulf sturgeon. 
Manuscript submitted 13 April 2021. 
Manuscript accepted 14 October 2021. 
Fish. Bull. 119:243-254 (2021). 
Online publication date: 12 November 2021. 
doi: 10.7755/FB.119.4.4 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Recruitment and survival of juvenile Gulf 
sturgeon (Acipenser oxyrinchus desotoi) in 
the Apalachicola River in Florida 
Adam G. Fox (contact author)' 
Nathaniel Q. Hancock’? 
J. Andrew Marbury? 
Adam J. Kaeser* 
Douglas L. Peterson (retired)' 
Email address for contact author: agfox@uga.edu 
" Warnell School of Forestry and Natural 
Resources 
University of Georgia 
180 East Green Street 
Athens, Georgia 30602 
? Northern District Office 
North Carolina Division of Marine Fisheries 
100 Kitty Hawk Lane 
Elizabeth City, North Carolina 27909 
The Gulf sturgeon (Acipenser oxyrin- 
chus desotoi) is a large-bodied, anad- 
romous fish found in drainages of the 
Gulf coast of the United States from 
Louisiana to Florida. Like most mem- 
bers of Acipenseridae, the Gulf sturgeon 
has a late age at maturity, a protracted 
spawning interval, and a long lifespan 
(Huff!; Nelson et al., 2013). These life 
history traits make sturgeon particu- 
larly vulnerable to anthropogenic dis- 
turbances (Rochard et al., 1990), and, as 
a result of population declines caused by 
overharvesting and habitat alteration, 
the Gulf sturgeon was listed as threat- 
ened under the Endangered Species Act 
in 1991 (Federal Register, 1991). 
Reproducing populations of Gulf stur- 
geon currently exist in 7 coastal river 
1 Huff, J. A. 1975. Life history of the Gulf 
of Mexico sturgeon, Acipenser oxyrinchus 
desotoi, in the Suwannee River, Florida. Fla. 
Dep. Nat. Resour., Mar. Resour. Publ. 16, 30 
p. [Available from Fla. Dep. Environ. Pro- 
tection, 3900 Commerce Blvd., Tallahassee, 
FL 32399-3000.] 
3 DeLeon Springs Fisheries Field Laboratory 
Northeast Region 
Florida Fish and Wildlife Conservation Commission 
5450 U.S. Highway 17 
DeLeon Springs, Florida 32130 
4 Panama City Fish and Wildlife Conservation Office 
U.S. Fish and Wildlife Service 
1601 Balboa Avenue 
Panama City, Florida 32405-3792 
systems from the Suwannee River, in 
Florida, to the Pear] River, in Louisiana 
(USFWS and NMFS, 2009). Research 
and monitoring of these populations has 
largely focused on the capture of juve- 
niles (>900 mm in total length [TL]) and 
adult fish (©1350 mm TL), by using gill 
nets with large mesh (212.7 cm stretch) 
(Sulak et al., 2016). Results of these 
efforts indicate that the Suwannee River 
has the largest population, with an esti- 
mated abundance of 5000—10,000 adults 
and juveniles (Chapman et al., 1997; 
Sulak and Clugston, 1999; Sulak et al., 
2016). As summarized by Sulak et al. 
(2016), most recent estimates of juvenile 
and adult abundance in other rivers are 
substantially lower. Although quantify- 
ing juvenile and adult abundance does 
provide insights into long-term popula- 
tion trends, these estimates are not use- 
ful in assessing the effects of recovery 
actions aimed at improving the repro- 
ductive success of Gulf sturgeon because 
these changes will not be reflected in the 
adult population for many years. 
