50 
National Marine 
Fisheries Service 
NOAA 
Fishery Bulletin 
z* established In 1881 •<* 
Spencer F. Baird 
First U S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Using oxytetracydine validation for confirmation 
of changes in vertebral band-pair deposition rates 
with ontogeny in sandbar sharks (Carcharhinus 
plumbeus ) in the western North Atlantic Ocean 
Email address for contact author: lisa.natanson@noaa.gov 
Abstract —Age underestimation 
of many shark species, such as 
the sandbar shark (Carcharhinus 
plumbeus), has been proven with 
age validation methods including 
bomb radiocarbon dating, oxytet- 
racycline (OTC) injection, and tag- 
recapture data. Validation studies 
indicate that band-pair deposition 
in vertebral centra may not be di¬ 
rectly related to time, especially in 
older individuals of a species. In this 
study, vertebrae from tagged, OTC- 
injected, and recaptured sandbar 
sharks were examined to determine 
if band-pair deposition past the OTC 
mark matched time at liberty. In 6 
of 8 OTC-injected sharks at liberty 
for >1 year, band-pair count past 
the OTC mark underestimated time 
at liberty by 24-58%. Additionally, 
growth rates derived from tag-re¬ 
capture data were slower than those 
described by previously published 
vertebral band-pair growth curves 
but were similar to those predicted 
by previous bomb radiocarbon dating 
and OTC results from this study. To¬ 
gether, the results from these stud¬ 
ies indicate that modeling tag-re¬ 
capture data may be more accurate 
for age determination in elasmo- 
branchs given that band-pair counts 
on vertebral centra do not coincide 
with age throughout life. Analyses 
indicate that sandbar sharks may 
be less productive than previously 
understood. 
Manuscript submitted 13 August 2018. 
Manuscript accepted 20 December 2018. 
Fish. Bull. 117:50-58 (2019). 
Online publication date: 8 February 2019. 
doi: 10.7755/FB.117.1.6 
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. 
Lisa J. Natanson (contact author ) 1 
Bethany M. Deacy 2 
1 Northeast Fisheries Science Center 
National Marine Fisheries Service, NOAA 
28 Tarzwell Drive 
Narragansett, Rhode Island 02882 
2 Riverside Technologies, Inc. 
for National Marine Fisheries Service, NOAA 
3500 Delwood Beach Road 
Panama City, Florida 32408 
Research has shown that the rate 
of vertebral band-pair deposition in 
elasmobranchs is variable and not 
necessarily related to time (Harry, 
2018; Natanson et al., 2018). At least 
30% of studies attempting to validate 
the periodicity of vertebral band-pair 
deposition in elasmobranchs in rela¬ 
tion to age have shown that ages 
were underestimated (Harry, 2018). 
Results from the use of oxytetracy- 
cline (OTC) injection, tag-recapture 
data, and bomb radiocarbon dating 
for validation indicate that band- 
pair deposition in sharks can ap¬ 
proximate time in certain life stages 
(e.g., Campana et al., 2002; Natan¬ 
son et al., 2002; Francis et al., 2007; 
Andrews et al., 2011; Wells et al., 
2013; Hamady et al., 2014; Passerot- 
ti et al., 2014; Natanson and Skom- 
al, 2015; Kinney et al., 2016; Harry, 
2018). A change in band-pair deposi¬ 
tion rate often occurs at the approach 
of maturity, indicating that band- 
pair deposition rate changes with 
shifts in the growth rate associated 
with energetic demands required by 
a maturing fish. In some species, 
such as the Pacific angel (Squatina 
californica) and basking (Cetorhinus 
maximus) sharks, there is no appar¬ 
ent link to time at any life stage (Na¬ 
tanson and Cailliet, 1990; Natanson 
et al., 2008). Furthermore, examina¬ 
tion of vertebral band-pair counts in 
relationship to vertebral and somatic 
growth in 7 elasmobranch species 
has revealed a relationship between 
body girth and band-pair deposition. 
This finding indicates that, although 
there may be a coincidental link to 
time in band-pair deposition, band- 
pair deposition is more likely related 
to vertebra] structure (Natanson et 
al., 2018). The results of all of these 
studies reemphasize the importance 
of direct validation of all sizes of a 
species (Beamish and McFarlane, 
1983). 
The sandbar shark (Carcharhinus 
plumbeus ) is a common coastal car- 
charhinid that is widely distributed 
in the world’s oceans (Ebert et al., 
2013). In the western North Atlantic 
Ocean, the sandbar shark is distrib¬ 
uted from southern Massachusetts to 
Florida, into the Gulf of Mexico, and 
to southern Brazil (Castro, 2011). 
This shark has been the primary 
