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Fishery Bulletin 102(1) 



Figure 7 



Images of otoliths from two sablefish showing differences in otolith growth rate. Both 

 fish were injected with OTC in early October of 1991 and were recaptured in May of 

 1992. (Al Otolith was from a 597-mm female caught in 680 meters of water at 40°52' 

 latitude. iBl Otolith was from a 610-mm female fish caught in 480 meters of water at 

 41°52' latitude. The OTC mark in A was on the edge, whereas the position of the OTC 

 mark in B is shown on the insert. 



are important factors in developing reliable and consistent 

 age determination criteria. 



The importance of using the same age determination 

 criteria among readers cannot be overestimated. In the 

 blind comparison, the readers were asked whether they 

 had included the edge in their count of annual zones. With 

 standard age determination methods, if no hyaline mate- 

 rial is visible on the edge up to about May, then the edge is 

 counted. This procedure is based on the assumption that a 

 zone is in the process of forming but is not yet clearly vis- 



ible. On the other hand, if hyaline material is observed on 

 the edge after May, it is not counted because it is assumed 

 to be either a check or the beginning of the next winter's 

 hyaline zone. Reader 1 and reader 2 (the two most expe- 

 rienced age readers) agreed on whether to count the edge 

 96% of the time, indicating that they were using the same 

 criteria. Reader 3, however, agreed with reader 1 only 64% 

 of the time and with reader 2 only 68% of the time which 

 suggests that reader 3 was using different edge-interpreta- 

 tion criteria. 



