Elzey et al: Comparison of 4 aging structures for Alosa sapidissimo 
53 
Yilmaz and Polat (2002) with pontic shad, we did not 
find annuli easy to distinguish in opercula of the Amer- 
ican shad, especially in older (>6 years) fish. Further- 
more, our ages determined from opercula were biased 
compared with ages derived from otoliths, leading to 
fish of age 5 and older being under-aged. 
The results of this study support the use of otoliths 
for age determination of American shad. Ages estimat- 
ed from otoliths were more precise (between and with- 
in readers) than ages derived from any of the other 
structures examined. Campana (2001) suggested a CV 
of 5% or less is ideal for a species of moderate longev- 
ity. In this study, only ages from otoliths achieved a CV 
of less than 5% between and within readers. Ages esti- 
mated from scales and vertebrae were higher in young 
(<5 years) fish than ages determined from otoliths. 
Furthermore, ages estimated from scales and opercula 
were lower than ages from otoliths in older (<7 years) 
fish. If possible, a reference collection of otoliths should 
be compiled for each region for which age estimates 
would be useful. Such a collection could provide a valu- 
able tool for training inexperienced readers of annuli, 
as well as would prevent a long-term drift for age esti- 
mates determined by experienced personnel (Campana, 
2001 ). 
Acknowledgments 
We would like to thank the employees of the Massa- 
chusetts Division of Fisheries and Wildlife that helped 
sample American shad at the Essex dam in Lawrence. 
We also thank S. Turner for her help in processing 
samples. We also appreciate the thorough comments 
provided by M. Armstrong and G. Nelson on revisions 
at the manuscript stage. Funding for this project was 
provided, in part, through the Wildlife and Sport Fish 
Restoration Program of the U.S. Fish and Wildlife 
Service (Massachusetts Sport Fish Restoration Grant 
F-68-R). 
Literature cited 
Barnes, M. A., and G. Power. 
1984. A comparison of otolith and scale ages for western 
Labrador lake whitefish, Coregonus clupeaformis. En- 
viron. Biol. Fish. 10:297-299. 
Beamish, R. J., and H. H. Harvey. 
1969. Age determination in the white sucker. J. Fish. 
Res. Board Can. 26:633-638. doi: 10.1139/f69-057. 
Beamish, R. J., and G. A. McFarlane. 
1983. The forgotten requirement for age validation 
in fisheries biology. Trans. Am. Fish. Soc. 112:735- 
743. doi: 10.1577/1548-8659( 1983)112<735:TFRFAV> 
2.0.CO;2. 
Boxrucker, J. 
1986. A comparison of the otolith and scale methods for 
aging white crappies in Oklahoma. N. Am. J. Fish. Man- 
age. 6:122-125. doi: 10. 1577/1548-8659) 1986)6<122:AC 
OTOA>2.0.CO;2. 
Campana, S. E. 
2001. Accuracy, precision and quality control in age de- 
termination, including a review of the use and abuse 
of age validation methods. J. Fish Biol. 59:197-242. 
doi: 10.11 Il/j.l095-8649.2001.tb00127.x. 
Cating, J. P. 
1953. Determining age of Atlantic shad from their 
scales. Fish. Bull. 54:187-199. 
Chang, W. Y. B. 
1982. A statistical method for evaluating the reproduc- 
ibility of age determination. Can. J. Fish. Aquat. Sci. 
39:1208-1210. doi: 10.1139/f82-158. 
Collette, B. B., and G. Klein-MacPhee (eds). 
2002. Bigelow and Schroeder’s fishes of the Gulf of 
Maine, 3 rd ed., 748 p. Smithsonian Institution Press, 
Washington, D.C. 
Duffy, W. J., R. S. McBride, S. X. Cadrin, and K. Oliveira. 
2011. Is Cating’s method of transverse groove 
counts to annuli applicable for all stocks of Ameri- 
can shad? Trans. Am. Fish. Soc. 140:1023-1034. 
doi: 10.1080/00028487.2011.603985. 
Duffy, W. J., R. S. McBride, M. L. Hendricks, K. Oliveira. 
2012. Otolith age validation and growth estimation 
from oxytetracycline-marked and recaptured Ameri- 
can shad. Trans. Am. Fish. Soc. 141:1664-1671. 
doi: 10.1080/00028487.2012.720631 
Hassleman, D. J., D. Ricrad, and P. Bentzen. 
2013. Genetic diversity and differentiation in a wide 
ranging anadromous fish, American shad ( Alosa sapidis- 
sima ), is correlated with latitude. Mol. Ecol. 22:1558- 
1573. doi: 10.1111/mec.l2197. 
Hendricks, M. L., T. R. Bender Jr., and V. A. Mudrak. 
1991. Multiple marking of American shad otoliths 
with tetracycline antibiotics. N. Am. J. Fish. Manage. 
11:212-219. 
Latour, R. J., E. J. Hilton, P. D. Lynch, T. D. Tuckey, B. E. Wat- 
kins, and J. E. Olney. 
2012. Evaluating the current status of American shad 
stocks in three Virginia rivers. Mar. Coast. Fish. 
4:302-311 doi: 10.1080/19425120.2012.675978. 
Leggett, W. C., and J. E. Carscadden. 
1978. Latitudinal variation in reproductive characteris- 
tics of American shad (Alosa sapidissima ): evidence for 
populations specific life history strategies in fish. J. 
Fish. Res. Board Can. 35:1469-1478. doi: 10.1139/ 
f78-230. 
McBride, R. S., M. L. Hendricks, and J. E. Olney. 
2005. Testing the validity of Cating’s (1953) method for 
age determination of American shad using scales. Fish- 
eries 30:10-18. doi: 10.1577/1548-8446(2005)30[10:TT- 
VOCM]2,O.CO;2. 
Raabe, J. K., and J. E. Hightower. 
2014. American shad migratory behavior, weight loss, 
survival, and abundance in a North Carolina river fol- 
lowing dam removals. Trans. Am. Fish. Soc. 143:673- 
688. doi: 10.1080/00028487.2014.882410. 
Robillard, E., C. S. Reiss, and C. M. Jones. 
2009. Age-validation and growth of Bluefish (Poma- 
tomus saltatrix) along the East Coast of the LTnit- 
ed States. Fish. Res. 95:65-75. doi: 10.1016/j. 
fishres.2008.07.012. 
