Condini et al. : Age and growth of Epinephelus marginatus in the southwestern Atlantic 
319 
at the inshore habitat (10.6 and 35.1 during winter and 
summer, respectively) (A. Garcia, unpubl. data). In fact, 
faster growth was reported in dusky groupers reared 
under a salinity of 35 compared with dusky groupers 
reared under mixohaline treatments with salinities of 
20 and 27 (Gracia-Lopez and Castello-Orvay, 2003), in- 
dicating that less energy may be expended for body ho- 
meostasis in more salinity-stable marine waters than 
in more salinity-variable estuarine conditions. This 
evidence supports the hypothesis that salinity regimes 
may play a significant role in controlling the differen- 
tial growth rates of dusky groupers observed in inshore 
and offshore habitats. 
An additional environmental factor capable of in- 
fluencing fish growth in our system is food availabil- 
ity. The diet of groupers from the rocky jetties of Rio 
Grande consisted mostly of small crabs (Condini et al., 
2011), whereas groupers from the Carpinteiro Bank 
were found to feed mostly on fish (Condini, in press). 
Given that fish are known to be a higher-energy food 
resource than crustaceans (Renones et al., 2002), food 
quality also may partially explain the faster growth ob- 
served in dusky groupers sampled at the Carpinteiro 
Bank. 
Conclusions 
Accurate age and growth parameters of fish popula- 
tions are important for the efficiency of environmental 
protection actions. In this study, we have shown that 
dusky groupers from their southernmost population 
present growth performance similar to that observed 
worldwide, with maximum size and age of about 900 
mm TL and 40 years, respectively. We have also shown 
that younger individuals with ages between 3 and 6 
years sampled offshore (depths of 15-25 m) are larger 
on average than fish of the same age sampled inshore 
(depths <5 m). These findings indicate that offshore 
banks may provide higher quality habitats for dusky 
groupers than do inshore rocky habitats. Therefore, the 
dusky grouper population that inhabits this offshore 
bank should be a preferable target for fishery manage- 
ment actions (e.g., catch monitoring and fishing quotas) 
to prevent increases in the level of overfishing of this 
endangered species at its southernmost distribution 
limit in southwestern Atlantic. 
Acknowledgments 
We thank B. Ferreira, L. Romano, and G. Velasco for 
their comments on this manuscript, J. Castello for 
helping with infrastructure to process samples, L. 
Madureira for providing the 3-D bathymetric map of 
Carpinteiro Bank, and Osmas Moller for providing 
salinity data for the offshore site. M. Condini and A. 
Garcia acknowledge fellowship support from Conselho 
Nacional de Desenvolvimento Cientifico e Tecnologico 
(CNPq; 140570/2013-6 and 305888/2012-9, respective- 
ly). C. Albuquerque is currently a postdoctoral fellow 
(CAPES-PNPD 02907/09-7). This study received finan- 
cial support from the Fundagao O Boticario de Protegao 
a Natureza (0753-20072). 
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