618 
Fishery Bulletin 99(4) 
Map of artificial reef permit areas off Alabama. Date of creation is given for each area. 
ed there. The productivity of the red snapper fishery off 
Alabama occurs despite the fact that few high-relief (>1 
m) natural reefs exist on the continental shelf in the north 
central GOM (Parker et ah, 1983; Shultz et ah, 1987; 
Schroeder et ah, 1989); however, off the coast of Alabama 
exists a 3100-km 2 area designated for artificial reef de- 
ployment (Fig. 1). The correlation between high catch rates 
and the creation of artificial reefs off Alabama has caused 
some to speculate that artificial reefs have increased the 
productivity of the GOM red snapper stock in this area 
(Szedlmayer and Shipp, 1994; Minton and Heath, 1998). 
Despite the implied effect of artificial reefs on the red 
snapper fishery off Alabama, few studies have focused on 
red snapper in this area. The objective of our study was 
to estimate growth rates of adult red snapper captured 
off Alabama with otolith-aging and mark-recapture meth- 
ods and to compare growth estimates with growth of adult 
red snapper from the western GOM and the southeastern 
United States. As a corollary to our primary objective, 
we also attempted to validate presumed annual growth 
rings in otoliths with marginal increment analysis and 
present a comparison of estimated growth of otolith-aged 
red snapper with estimated growth of tagged individuals. 
Methods 
Otolith aging 
Red snapper were sampled from July 1995 to September 
1999. All fish were caught over artificial reef sites off Ala- 
bama. Red snapper shorter than the legal size limit (380 
mm total length [TL] for most of the study) were ran- 
domly sampled from undersize fish caught during research 
cruises to tag red snapper. Fish longer than the legal 
size limit were either randomly sampled from recreational 
catches or sampled opportunistically at spearfishing or 
hook-and-line fishing tournaments. Total length and fork 
length (FL) were measured to the nearest mm for all fish, 
and whole weight was measured to the nearest 0.1 g. Sex 
was determined for most fish by macroscopic examination 
of the gonads. Both sagittae were removed from each sam- 
pled individual, rinsed of any adhering tissue, and stored 
in paper coin envelopes until processing. 
Otoliths were sectioned in a transverse plane following 
the methods of Cowan et al. (1995) and were read under 
transmitted light with either a Micro Design® model 925 
microfiche projector or an Optimas® image analysis sys- 
tem (Media Cybernetics, 1999). Otoliths were read inde- 
pendently by two readers. Blind counts of opaque zones of 
each sectioned otolith were made along the ventral margin 
of the sulcus acousticus from the core to the proximal sur- 
face; marginal increments were scored following Beckman 
et al. (1991) (Table 1, Fig. 2). Otoliths for which counts of 
opaque zones differed between readers were read a second 
time. Precision among readers was evaluated with the co- 
efficient of variation (CV) (Chang, 1982), index of preci- 
sion (D) (Chang, 1982), and average percent error (APE) 
(Beamish and Fournier, 1981). 
Age was estimated from the number of opaque zones in 
otolith sections, timing of opaque zone formation, assumed 
birthdate, and sampling date. It was assumed that opaque 
