aspm.r

File contents

# aspm.r
 # aspm: Performs forward simulation of populations, given values of parameters
 aspm<-function(Fvec,Rvec){
   Yhat<-NULL
   Bhat<-NULL
   Rtemp<-Rvec[1]
   #N0<-Ninit                       # First start-of-year stock size - fixed
   N0<-Rtemp*exp(-cumsum(c(0,M[1:(length(M)-1)])))  # First start-of-year stock size - equil.
   for(year in 1:totyrs){
     baseF<-Fvec[year]              # Base fishing mortality
     F0<-baseF*selpat               # Fishing mortality during the year
     Ntemp<-N0*exp(-F0-M)           # Forw proj - gives ages 2:(g+1)
     Noldest<-Ntemp[g]+Ntemp[g+1]   # Allow for plus-group
     C<-(F0/(F0+M))*(1-exp(-(F0+M)))*N0
     Ytemp<-sum(C*w)                    # Total landings
     #print(Ytemp)
     Yhat<-c(Yhat,Ytemp)
     Bhat<-c(Bhat,sum(N0*w))
     Rtemp<-Rvec[year]
     N1<-c(Rtemp,Ntemp[1:(g-1)],Noldest)# Set up stock at end of year
     N0<-N1                         # Prepare for next round
   }
   return(list(Yhat=Yhat,Bhat=Bhat))
 }