He et at: Interactions of age-dependent mortality and selectivity functions in age-based stock assessment models 
213 
stock-recruitment relationships can be estimated at 
given levels of recruitment variability, data availabil- 
ity, and stock contracts are needed to provide general 
guidelines for estimating stock-recruitment relationship 
in assessment models. 
We believe that even with informative data and a 
correctly specified estimation model, there are strong 
interactions between natural mortality and fishery se- 
lectivity in stock assessment models. Misspecification 
of both parameters can lead to poor estimates of im- 
portant population and fishery parameters, which in 
turn can produce under- or over-estimates of important 
management quantities, such as stock depletion and 
OFL. Improvement in the assessment modeling ap- 
proach itself may not resolve these problems because 
of the interdependence of mortality, selectivity, and 
stock recruitment functions within the models. Uncer- 
tainty analysis of stock assessment models on age- or 
length-specific mortality and selectivity is also needed 
and should be included for assessments of model perfor- 
mance and for management of assessed stocks. 
Acknowledgments 
We thank E. Dick and J. Field for helpful comments on 
earlier versions of the manuscript. We also thank three 
anonymous reviewers for very helpful and constructive 
comments on earlier versions of the manuscript. 
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