Baremore and Rosati: A validated, minimally deleterious method for aging sturgeon 
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Figure 1 
The approximate range (the shaded area) and major spawning rivers of Gulf sturgeon (Acipenser oxyrinchus desotoi) in 
the Gulf of Mexico. Structures for aging Gulf sturgeon were collected from sturgeon captured in the Choctawhatchee 
River in 2010, from archived specimens from the Apalachicola and Choctwahatchee rivers in 2010, and from an archive 
of Gulf sturgeon captured on the Suwannee River in 1980-90. 
spine (Rien and Beamesderfer, 1994; Rossiter et al., 
1995; Stevenson and Secor, 1999; Berg, 2004; Hurley 
et al., 2004; Whiteman et al., 2004; Allen et al., 2009). 
Kahn and Mohead (2010) advised against the use of 
the fin spine in mature shortnose, Atlantic, Gulf, and 
green sturgeon because of increased reader error, ab- 
normal regrowth, and an increased chance of deleteri- 
ous effects. To reduce harm to endangered and threat- 
ened species and to increase standardization for aging 
protocols, options other than the fin spine should be 
developed. 
Another important aspect of age and growth that 
is often ignored is the validation of annual band for- 
mation in aging structures (Beamish and McFarlane, 
1983; Campana, 2001). Despite the widespread use 
of the pectoral spine for age estimation (Rien and 
Beamesderfer, 1994; Rossiter et al., 1995; Morrow et 
al., 1998; Stevenson and Secor, 1999; Hurley et ah, 
2004; Whiteman et ah, 2004), successful validation of 
annual band formation in the pectoral spine has been 
published for only 2 North American sturgeon species: 
white (Rien and Beamesderfer, 1994) and lake (Rossiter 
et ah, 1995) sturgeon. Accurate age estimation is criti- 
cal because it forms the basis for calculating growth 
and mortality rates, age at maturity, and estimates of 
longevity, all of which are essential for the production 
of accurate population models. 
For this study, we had the following objectives: 1) to 
evaluate and compare banding patterns from the pecto- 
ral spines, fin rays, and otoliths of Gulf sturgeon; 2) to 
determine which aging structure, for which removal is 
nonlethal and minimally deleterious, provides the most 
accurate and consistent band counts; 3) to validate the 
frequency of band formation within the preferred aging 
structure; and 4) to provide the field and laboratory 
methods to remove, process, and interpret the validat- 
ed aging structure for Gulf sturgeon. 
Materials and methods 
Sampling protocol 
To determine the best aging structure for Gulf stur- 
geon, 14 frozen Gulf sturgeon from previous mortality 
events on the Choctawhatchee and Apalachicola rivers 
(Fig. 1) were sampled in 2010. The fin spine, second 
marginal pectoral-fin ray (the fin ray just posterior to 
the fin spine), pectoral-, dorsal-, pelvic-, and anal-fin 
rays, and sagittal otoliths were removed, cleaned, and 
