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



195 



B 



California 



1983 



r 1onth 



Wide opaque Hyaline Narrow opaque 



Figure 2 (continued) 



The late onset of opaque-zone development may be 

 related to ocean temperature. 



The 1983 El Nino event began early in the year 

 (Fig. 3). During the spring of 1983, sea-surface tem- 

 perature was the warmest of all spring temperatures 

 from 1983 through 1987. In addition, the minimum 

 temperature off California occurred later in 1983 than 

 in other years. These environmental changes coincide 

 with the late formation of the hyaline zone in 1983. 



The temperature-hyaline zone formation relation- 

 ship is supported by the fact that the timing of the 

 spring sea-surface temperature minimum in Wash- 



ington is more constant than in California (Fig. 3). 

 This is similar to the pattern observed in hyaline- 

 zone formation in otoliths between the two states. 

 Finally, the temperature declines earlier in Wash- 

 ington than it does in California, which is consistent 

 with the earlier onset of hyaline-zone formation in 

 otoliths from fish in Washington. Although the link 

 between temperature and hyaline-zone formation is 

 not conclusive, it is suggestive. It is possible that 

 some factor, related to temperature, is responsible 

 for formation of the annulus (e.g. food availability or 

 nutrient content of prey). 



