BevertonHolt: Beverton and Holt biomass and yield per recruit calculation.

In sandroklippel/fishassess: Functions on fishery biology, stock assessment and management.

Description

Beverton and Holt biomass and yield per recruit calculation for a given set of parameters. Default method is numerical integration, but also Gulland approximation and relative yield concept are available.

Usage

Beverton.Holt(F, M, Tr, Tc, Tmax, Wt, approxim="i")
Beverton.Holt(F, M, Tr, Tc, Tmax, Winf, K, t0, b=3, approxim="i")
Beverton.Holt(F, M, Tr, Tc, Winf, K, t0, b=3, approxim="g")
Beverton.Holt(FZ, Lc, Linf, MK, approxim="r")

Arguments

F	fishing mortality rate.
M	natural mortality rate.
Tr	age at recruitment.
Tc	age at first capture.
Tmax	maximum age attained.
Wt	weight at age (function).
Winf	asymptotic weight.
K	growth rate.
t0	age at zero length.
b	exponent in length-weight relationship.
FZ	exploitation rate, F/Z.
Lc	length at first capture, L50.
Linf	asymptotic length.
MK	M/K.
approxim	method for estimate the integral.

Value

An object of the class BH or BH.rel with the components

YR	yield per recruit.
BR	biomass per recruit.
...	input parameters.

Author(s)

Sandro Klippel

References

Beverton, R., Holt, S., 1957. On the dynamics of exploited fish populations. Vol. 2. Sea Fish. Min. Agric. Fish Food G. B.

Beverton, R., Holt, S., 1966. Manual of methods for fish stock assessment - Part 2. Tables of yield functions. Vol. 38/1 de FAO Fisheries Technical Papers. FAO, Rome.

Quinn, T., Deriso, R., 1999. Quantitative fish dynamics. Oxford University Press, New York - Oxford.

Sparre, P., Venema, S., 1998. Introduction to tropical fish stock assessment - Part 1: Manual. Vol. 306/1 of FAO Fisheries Technical Paper. FAO, Rome.

See Also

plot.BH, profile.BH, F0.1, Fmax, isopleths

Examples

BHx <- Beverton.Holt(F=0.6, M=0.2, Winf=3000, K=0.25, t0=-0.2, Tr=1, Tc=5, approxim="g")
BHy <- Beverton.Holt(F=0.6, M=0.2, Winf=3000, K=0.25, t0=-0.2, b=2.8, 
                     Tr=1, Tc=5, Tmax=25, approxim="i")

# It can be of observed values
TWobs <- VBGFw(1:40, Winf=3000, K=0.1, t0=-0.2, b=2.9) 
BHz <- Beverton.Holt(F=0.6, M=0.2, Wt=function(t){ TWobs[t] }, Tr=1, 
                     Tc=5, Tmax=40, approxim="i") 

## Not run: 

## Monte Carlo approach
## This code does not run directly with example()

F <- rep(NA, 500)
for (i in 1:500){
  F[i] <- F0.1(Beverton.Holt(
  Wt=function(t){rnorm(1,mean=VBGFw(t, Winf=3000, K=0.25, t0=-0.2),
  sd=300)}, Tr=1, Tc=5, Tmax=25, F=1, 
  M=runif(1, min=0.175, max=0.275)))
}
library(MASS)
truehist(F, xlab="F0.1", col="white")
lines(density(F), lwd=2)

## End(Not run)

sandroklippel/fishassess documentation built on June 5, 2019, 10:54 a.m.