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Fishery Bulletin 90(1). 1992 



follicles to be resorbed. We used this batch-order clas- 

 sification system to determine if batch fecundity varied 

 with the order of the spawnings, as it does in some 

 species (Alheit 1986, Hunter et al. 1989). 



Estimation of length at 50% mature 



We estimated the total length (mm) of female Dover 

 sole when 50% had become mature using histological 



criteria. The fraction of females considered to be 

 mature was estimated for 10 mm or for 50 mm length- 

 classes, and the data were fit to a logistic curve (Dixon 

 et al. 1988). We estimated the maturity threshold for 

 females taken off central California and off Oregon, 

 before and during the spawning season. In our analysis, 

 we evaluated the extent to which changes in histo- 

 logical criteria affected the maturity estimate using six 

 sets of histological criteria: (1) advanced yolked 



