NOTE Pearson Timing of hyaline-zone formation in otoliths of Sebastes entomelas 



193 



Jan 



Mar 



Vay 



Jul 



Sep 



Sep 



Figure 1 



Marginal increment comparison for widcw rockfish, Sebastes entomelas, be- 

 tween Washington and California for the years 1983-87 combined (unweighted 

 means) and sexes combined. Large opaque is defined as an opaque edge >l/2 

 the size of the, previous opaque zone; small opaque is defined as an opaque 

 edge <l/2 the previous opaque zone. 



were no differences in edge types for the months of 

 January, April, or July. This difference appears to be 

 due to the tendency of females in California to have 

 a smaller portion of their population with hyaline 

 edges and more of both late opaque and early opague 

 edges in March. Males tended to be similar among 

 states. 



Discussion 



Significant differences in the time of hyaline-zone 

 formation exist among years and states and may have 



important ramifications for age determination. It is 

 important to consider whether differences in the sea- 

 sonal expression of the hyaline zone might cause er- 

 rors in age determination and. if so, what type of 

 errors might occur. 



By convention all fish are considered to be born on 

 1 January (Chilton and Beamish, 1982) to assure 

 proper year-class identification. In addition, if the 

 edge appears hyaline before January, it is not 

 counted, and if it is opaque after December, a hyaline 

 edge is assumed to be present and therefore counted. 



The results of this study indicate that the hyaline 

 zone forms earlier in otoliths from fish in Washing- 



