A validated, minimally deleterious method for 
aging sturgeon 
Email address for contact author: ivalina1@gmail.com 
Panama City Laboratory 
Southeast Fisheries Science Center 
National Marine Fisheries Service, NOAA 
3500 Delwood Beach Road 
Panama City, Florida 32408 
Present address for contact author: MarAlliance 
P.O. Box 283 
San Pedro, Ambergris Caye 
Belize, Central America 
Abstract— To determine the most 
suitable aging structure for stur- 
geons, band counts of transverse 
sections of otoliths and the pectoral-, 
dorsal-, pelvic-, and anal-fin rays of 
Gulf sturgeon (Acipenser oxyrinchus 
desotoi) were compared. The otoliths 
and dorsal-, pelvic- and anal-fin rays 
produced inconsistent band patterns, 
but bands formed in the first (fin 
spine) and second marginal pecto- 
ral-fin rays were easily read and the 
most consistent. The index of aver- 
age percent error and the coefficient 
of variation between final ages from 
the fin spines and the second mar- 
ginal fin ray were 0.75% and 1.06%, 
respectfully. Percent agreement be- 
tween the assigned age of the fin 
spine and second marginal fin ray 
was high. The fin spine is commonly 
used to age sturgeon species; how- 
ever, removal of the fin spine was 
considered potentially deleterious, 
especially to larger sturgeon. Sam- 
pling the second marginal fin ray 
appeared to be less harmful. Annual 
band formation in the second mar- 
ginal fin ray for 3 Gulf sturgeon was 
validated with the use of oxytetra- 
cycline. We propose the second mar- 
ginal pectoral-fin ray as an accept- 
able and less harmful alternative 
structure to the fin spine for aging 
Gulf sturgeon and recommend its 
use for other threatened and endan- 
gered sturgeon species. An extrac- 
tion method of minimal invasiveness 
is presented here for field removal of 
the second marginal pectoral-fin ray 
from live sturgeon. 
Manuscript submitted 2 July 2013. 
Manuscript accepted 30 July 2014. 
Fish. Bull. 112:274-282 (2014). 
doi:10.7755/FB. 112.4.4 
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. 
Ivy E. Baremore (contact author) 
J. Drew Rosati 
Many sturgeon species are prized 
for their meat and caviar, and heavy 
fishing effort during the 19 th centu- 
ry greatly reduced population sizes 
around the world (Birstein, 1993). 
Of the 26 sturgeon species assessed 
by the International Union for Con- 
servation of Nature and Natural Re- 
sources and listed on the IUCN Red 
List of Threatened Species, 18 (69%) 
are listed as endangered or critical- 
ly endangered (vers. 2012.2, http:// 
www.iucnredlist.org, accessed March 
2013). Additionally, 20 of these spe- 
cies are listed as decreasing in popu- 
lation: only 4 sturgeon species are 
listed as increasing or stable and 2 
have unknown population trends. 
North America is home to 9 species 
of sturgeon, 8 of which are listed as 
threatened or endangered under the 
U.S. Endangered Species Act (U.S. 
Fish and Wildlife Service, Species 
Reports, Environmental Conserva- 
tion Online System, http://ecos.fws. 
gov/tess_public, accessed March 
2013; NMFS 1 ): shortnose ( Acipenser 
brevirostrum), green (A. medirostris), 
Atlantic (A. oxyrinchus), Gulf (A. 
oxyrinchus desotoi), white (A. trans- 
montanus), pallid (Scaphirhynchus 
albus ), shovelnose ( S . platorynchus), 
1 NMFS (National Marine Fisheries Ser- 
vice). 2013. Endangered and threat- 
ened marine and ana-dromous fish. 
[Available from http://www.nmfs.noaa. 
gov/pr/species/esa/fish.htm, accessed 
March 2013.]. 
and Alabama (S. suttkusi). Sturgeon 
generally exhibit slow growth and 
late maturation — life history charac- 
teristics that make populations slow 
to recover from exploitation. More- 
over, these life history traits, as well 
as habitat issues, equate to a diffi- 
cult recovery process. 
Age estimates of several spe- 
cies of sturgeon in North America 
have been evaluated by removing 
and observing the banding patterns 
of calcified structures, such as the 
first marginal pectoral-fin ray, oto- 
liths, scutes, opercula, and sphenoids 
(Brennan and Cailliet, 1989; Naka- 
moto et al. 2 ; Rossiter et ah, 1995; 
Stevenson and Secor, 1999; Hurley et 
ah, 2004; Jackson et ah, 2007; Bruch 
et al., 2009). Although it is not a true 
spine, the first marginal pectoral-fin 
ray of sturgeons commonly is called 
the fin spine, and hereafter it will be 
referred to as such in this article. All 
structures except the fin spine have 
proved to be detrimental to or have 
required sacrifice of the fish (Bren- 
nan and Cailliet, 1989); therefore, 
the most widely used aging struc- 
ture for sturgeon species is the fin 
2 Nakamoto, R. J., T. T. Kisanuki, and 
G. H. Goldsmith. 1995. Age and 
growth of Klamath River green stur- 
geon (Acipenser medirostris). U.S. Fish 
and Wildlife Service Project # 93-FP-13, 
20 p. [Available from Yreka Fish and 
Wildlife Office, U.S. Fish and Wildlife 
Serice, 1829 South Oregon St., Yreka, 
CA 96097.1 
