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Fishery Bulletin 100(4) 



ily on assumptions about fishery selectivity and discard 

 used in the latest assessment model-parameters that are 

 poorly known for most West Coast fish stocks. The modest 

 effect on harvest rate found in our study also does not pre- 

 clude larger effects for other, later maturing stocks. In the 

 example given earlier from Lunsford's (1999) simulation 

 work with Pacific ocean perch, the drop in target harvest 

 rate was much larger. In that instance, a shift of 3 years 

 in the median age of female maturity resulted in a 31'% 

 drop in the target harvest rate. In that example, spawning 



stock biomass per recruit also fell to 31'7f, well under the 

 target ofF,,,,,.. 



The maturity data developed in our study differ from 

 those developed by Turnock et al.-^ primarily in the steep- 

 ness of the maturity curve. It could be argued that the 

 earlier curve is flatter simply because it incorporates 

 data from a wider geographic range. A latitudinal cline in 

 length at 50% maturity, as has been postulated for many 

 flatfish stocks (Ketchen and Forrester, 1966; Castillo, 

 1995; Brodziak and Mikus, 2000), could cause flattening 



