262 



Fishery Bulletin 97(2), 1999 



Presumed tme 

 s age 



2 3 4 5 6 7 8 9 10 11 12 13 



Observed age 



Actual true age 



2 3 4 5 6 7 8 9 10 11 12 13 



Observed age 



Figure 4 



Estimated probability of observing a given age for a particular true 

 age of sablefish estimated from primary-reader and tester ages 

 (A, case 1) and from reader and known ages (B, case 6). Case refers to 

 model specifications listed in Table 1. 



helped improve this manuscript. We thank JuHe 

 Lyons for serving as the tester for this study and our 

 co-workers that tagged numerous juvenile sablefish 

 throughout southeastern Alaska. Our appreciation 

 is also extended to the many observers and scien- 

 tists who provided otoliths of recaptured sablefish. 

 We also thank James lanelli for helping implement 

 estimation of the ageing-error matrix. 



Literature cited 



Akaike, H. 



1974. A new look at the statistical identification model. 

 Institute of Electrical and Electronic Engineers (IEEE) 



Trans. Auto. Control 19:716-72.3. [Referred to in Richards 

 et al. (1992).] 

 Beamish, R. J., and D. E. Chilton. 



1982. Preliminary evaluation of a method to determine the 

 age of sablefish tAnoplopnina fimbria). Can. J. Fish. 

 Aquat. Sci. .39:277-287. 



Beamish, R. J., G. A. McFarlane, and D. E. Chilton. 



1983. Use of oxytetracyclme and other methods to validate a 

 met hod of age determination for sablefish. In Proceedings of 

 the second international sablefish symposium, p. 9.5-116. 

 Alaska Sea Grant Rep. 83-8. Univ. Alaska. Fairbanks, AK. 



Chilton, D. E., and R. J. Beamish. 



1982. Age determination methods for fishes studied by the 

 groundfish program at the Pacific Biological Station. Can. 

 Spec. Publ. Fish. Aquat Sci. 60, 102 p. 

 Ericksen, R. P. 



1997. Estimation of aging accuracy and precision, growth, 



