242 



Fishery Bulletin 98(2) 



nant adult stage (because this is the only stage 

 that is reproductively active). The highest elastic- 

 ities were for the transition from neonate to juve- 

 nile and juvenile to subadult stages (Fig. 2). The 

 elasticities for sharks remaining in the stage were 

 equal for neonate, juvenile, subadult, and pregnant 

 female stages. As discussed, the individual elastici- 

 ties can be summed to estimate the overall contri- 

 bution of each stage to A. It is clear from Figure 2 

 that the peak elasticity occurs in the subadult stage. 

 Estimates of elasticity suggest that the model is 2.3 

 times more sensitive to changes in this stage than in 

 pregnant adults. 



Estimate of Fc«/r/c>ii 



The relation between F and r is linear ( Fig. 3 ). Fp^^j-^ 

 f.^^ = 0.071 when M - 0.10. Therefore, the population 

 is sustainable if F = 0.071. The value of Ff^^/y-^f.^^ will 

 vary with the value of M that is chosen. Our analy- 

 ses showed that total mortality (Z) must be less than 

 0.17 for all stages if the population is to increase (Fig. 

 4). The population will increase at a rate r = 0.05 if Z 

 = 0.122, and the population will decrease at a rate r = 

 -0.05 if Z = 0.222. 



At FcRiTiCAL' ^^^ population abundance stabilizes 

 and the population reaches a stable stage distribu- 



