160 



R. J. H. Beverton and S. J. Holt 



Interspecific relations between maximum age (Tj^ax)* 



mortality rate (M), asymptotic length (L^) and 



growth rate (K) 



Table I lists, for each species, values of a pair of parameters 

 defining lifespan and the force of mortality {T^^^ and M) and 

 a pair defining the asymptotic size of the organism and the 

 rate at which that size is attained {L^ and K). The para- 

 meters T^iax ^^d ^ ^r^' of course, closely linked on purely 



50 lOO 



mathematical grounds ; there is no a priori reason why L^and_ 

 K should be, but it appears from the data that they ar'e fairly, 

 closely correlated (inversely), although there are some im- 

 portant exceptions. In this paper we therefore consider only 

 two of the possible relationships, that between T^^ax ^^^ -^oo 

 concerning the extremes of age and size, and that bfijtw£^n 

 M and K which, in effect, refer to the course of events within 

 the lifespan. Other possible relationships which might give a 

 better interpretation of the available data are under investiga- 

 tion. 



