find_msyr: calculate MSYR

In ktmurray1219/mmrefpoints: Project Marine Mammal Populations and Calculate Reference Points

Description

one of the functions needed for getting MNPL. MSYR is the same as FMSY.

Usage

find_msyr(E.start, lh.params, fmax)

Arguments

E.start	a starting guess for bycatch mortality rate that will result in FMSY (numeric value)
lh.params	a list of life history parameters (S0, S1plus, nages, AgeMat, lmabdaMax, K1plus, and z)
fmax	Max theoretical fecundity (num)

Examples

# Set parameters
S0.w = 0.5; S1plus.w = 0.944; nages.w = 25; K1plus.w = 9000; AgeMat.w = 18 
InitDepl.w = 0.9; z.w = 2.39; lambdaMax.w = 1.04
lh.params = list(S0 = S0.w,S1plus = S1plus.w, nages = nages.w,
AgeMat = AgeMat.w,K1plus=9000,z=z.w,lambdaMax = lambdaMax.w) 
# Get number of individuals per recruit in terms of mature individuals (\eqn{N0.w})
NPROut <- npr(S0 = S0.w, S1plus = S1plus.w, nages = nages.w, AgeMat = AgeMat.w, E = 0)
N0 <- NPROut$npr # mature numbers per recruit
# Get number of individuals per recruit in terms of individuals aged 1+ (\eqn{P0.w})
P0 <- NPROut$P1r # 1+ nums per recruit

fmax <- getfecmax(lambdaMax = lambdaMax.w, S0 = S0.w, S1plus = S1plus.w, AgeMat = AgeMat.w)
Fec0 <- 1.0 / N0
A <- (fmax - Fec0) / Fec0
fmsy<-find_msyr(E.start=0.01, lh.params=lh.params, fmax=fmax)
cat("fmsy =",fmsy,"\n")
results <- matrix(0,ncol=2,nrow=101)
results[,1] <- c(0:100)*fmsy/50
for (II in 1:101)
 results[II,2] <- ce(S0 = S0.w, S1plus = S1plus.w, nages = nages.w, AgeMat = AgeMat.w,z = z.w,
                     E=results[II,1], A = A, P0 = P0, N0 = N0)
plot(results[,1],results[,2],xlab="f",ylab="ce",type="l",yaxs="i",ylim=c(0,max(results[,2])*1.2))
abline(v=fmsy)

ktmurray1219/mmrefpoints documentation built on Dec. 21, 2021, 8:40 a.m.