Punt: Managing West Coast groundfish resources through simulations 



873 



It should also be noted that no account is taken of uncer- 

 tainty regarding the current age structure, natural mortal- 

 ity, selectivity, etc., although the projections do account for 

 uncertainty about future recruitment 



year in which the spawning output first reaches 0.48^. T^^^ 

 is the median of the distribution for this year constructed 

 by conducting projections for many different (random) 

 realizations of future recruitment. 



Selecting the maximum allowable rebuilding period 



The maximum allowable rebuilding time, T^^^, is defined 

 as the maximum of 10 years and the sum of the mean 

 generation time and the minimum possible rebuilding 

 time. This specification implements the requirement of 

 the SFA to "take into account the status and biology of any 

 overfished stocks offish, [and] the needs of fishing commu- 

 nities." The minimum possible rebuilding period for a given 

 future projection is computed by projecting the population 

 forward with zero fishing mortality and by identifying the 



Calculating the target fishing mortality rate 



The target fishing mortality rate and hence the harvest 

 guideline are determined by projecting the population 

 forwards many times ( 100 times for the purposes of this 

 paper), each time with a different sequence of future 

 recruitment and for a variety of alternative Fs and then 

 identifying the level of F that corresponds to the spawning 

 output having reached 0.4B(, by T^^^ with the prespecified 

 probability p. 



