NOTE Secor et al.: Validation of otolith-based ageing in Morone saxatilis 



189 



(Scofield, 1928, a and b). However, the popularity and 

 ease of age estimations using scales caused investi- 

 gators to overlook the importance of verifying age- 

 ing methodology (Beamish and McFarlane, 1983). 



All stock assessments on migratory populations of 

 striped bass currently rely on interpreting annular fea- 

 tures on scales, a largely unvalidated method. Annu- 

 lus formation in scales of striped bass has been veri- 

 fied for fish up to age three (Humphreys and Kornegy, 

 1985) and four years (Heidinger and Clodfelter, 1987) 

 in nonmigratory striped bass. Our data indicated that 

 annuli in scales may adequately estimate age for fish 

 less than 12 years of age. Thereafter, scales provided a 

 continuous age distribution between 11 and 20 years 

 of age, and otolith ageing indicated an absence offish 

 corresponding to these ages (Fig. 2). Therefore, we in- 

 ferred that otolith-based age determination will pro- 

 vide more accurate estimates after 12 years of age. 



A major disadvantage of using otoliths for age de- 

 terminations is that fish must be sacrificed. Because 

 large and old members of coastal populations have 

 potentially high reproductive values and may be 

 important contributors to annual recruitments (Rago 

 and Goodyear, 1987; Zastrow et al., 1989; Secor et 

 al., 1992; Cowan et al., 1993), it may be undesirable 

 to sacrifice large numbers of these individuals for 

 stock assessment purposes. An alternative approach 

 would be to correct the age estimates from scales by 

 using an otolith vs. scale calibration curve (Fig. 2). 

 Our reported relationship was somewhat variable 

 (^=0.85), but with additional otolith samples, reliable 

 prediction of age from scale annuli may be possible. 



Acknowledgments 



Jim Van Tassel, Jorgen Skjeveland, Rick Schaefer, 

 Jim Markham, Don Cosden, Marty Gary, David 

 Goshorn, and Scott Barbour provided samples of 

 CWT adults. Ken Booth provided samples of CWT 

 adults and aged scale samples for this study. Bunky^ 

 Charter Boat Service provided samples of migratory 

 Chesapeake Bay striped bass. Mike Mangion assisted 

 in interpretation of CWT-tags and annuli in scales, 

 respectively. This research was supported by the U.S. 

 Fish and Wildlife Service Emergency Striped Bass 

 Study (F&W Contract 14-48-0009-92-934 to Chesa- 

 peake Biological Laboratory) and Maryland Depart- 

 ment of Natural Resources. 



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