724 



Fishery Bulletin 103(4) 



lar case of blue shark, where most individuals caught 

 are released (dead or alive), fishing mortality is best 

 estimated from the number of animals released dead, 

 rather than from all animals caught. Because larger 

 animals have a higher probability of being released 

 alive, a logistic selectivity function without size or age 

 survival adjustment, could lead to overestimation of 

 impacts on the stock. Thus, a dome-shaped selectivity 

 function that incorporates the size-based survival infor- 

 mation presented in the present study may represent an 

 improvement over current techniques. 



Acknowledgments 



We thank L. Brooks, E. Cortes, S. Turner, and two 

 anonymous reviewers for invaluable comments on the 

 manuscript. 



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