-22- 



If the spawning stress mortality rate were the same for all species, we 

 could construct the mean year class strength directly if the fishing mortality 

 were known. Furthermore, using age composition data for a given year, we could 

 compute back to what any year class strength was when the year class was first 

 considered fully exploited, and what it would be in future years. 



However, spawning stress mortality rate cannot be considered universally 

 applicable. It is considerably higher in salmonids (including capel in) and also 

 in some pelagic fish (e.g., anchovy). It might also vary in the same species 

 with latitudes, as temperature affects the growth rate and maturation is a 

 function of size in many species. 



