Fishery Bulletin 89(1), 1991 



and Dean 1983, Radtke et al. 1985, Reznick et al. 1989, 

 Secor et al. 1989). Since fish length or weight accounts 

 for significant variability in age after considering 

 otolith weight, large fish have larger otoliths than 

 equal-aged small fish, i.e., otolith growth is affected by 

 fish growth. These observations support the proposi- 

 tion by Secor and Dean (1989) that not only do otoliths 

 grow in a continuous manner, independent of somatic 

 growth, but also that otolith growth is coupled in some 

 manner to somatic growth. 



These growth patterns should be considered when 

 using otoliths for back-calculation of fish size at age. 

 Since continued otolith growth uncoupled from somatic 

 growth would result in slower-growing fish having 

 larger otoliths at a given fish size, the fish-otolith size 

 relationship would be different for fast-growing and 

 slow-growing fish. This bias would be more pronounced 

 at older ages, since otolith growth could continue even 

 if somatic growth has stopped. 



Due to gear selectivity and sorting of some samples 

 by fishermen, the age distribution of our samples was 

 not considered to be representative of the Louisiana 

 sheepshead population. Future research should include 

 fishery-independent sampling to accurately character- 

 ize the age structure of the sheepshead population, 

 determine variability in recruitment, estimate mor- 

 tality rates, and identify sources of variability in 

 growth. Additional samples of older fish are required 

 to complete validation of age estimates for the oldest 

 individuals. 



Acknowledgments 



Sampling efforts were supported by the Louisiana 

 State University's Sea Grant Developmental Program, 

 and the Louisiana Board of Regents. We thank the 

 seafood dealers (including Preston Battistella, Fred and 

 Debbie Black, and Harlon Pearce), tournament organ- 

 izers, and fishermen for providing samples and facil- 

 ities. Thanks to Dean Blanchard, David Nieland, 

 Robert Parker, David Stanley, and Bruce Thompson 

 for assistance in data collection. 



Citations 



Barger, L.E. 



1985 Age and growth of Atlantic croakers in the northern Gulf 

 of Mexico, based on otolith sections. Trans. Am. Fish. Soc. 

 114:847-850. 

 Beamish, R.J. 



1979 New information on the longevity of the Pacific ocean 

 perch (Sebastes alutus). J. Fish. Res. Board Can. 36: 

 1395-1400. 

 Beamish, R.J., and D.A. Fournier 



1981 A method for comparing the precision of a set of age 

 determinations. Can. J. Fish. Aquat. Sci. 38:982-983. 

 Beckman, D.W., C.A. Wilson, and A.L. Stanley 



1989 Age and growth of red drum, Sciaenops ocellatus, from 

 offshore waters of the Northern Gulf of Mexico. Fish. Bull., 

 U.S. 87:17-28. 

 Beckman, D.W., A.L. Stanley, J.H. Render, and C.A. Wilson 

 1990a Age and growth of black drum in Louisiana waters of 

 the Gulf of Mexico. Trans. Am. Fish. Soc. 119:537-544. 



