calc_growth: Calculate growth

In LeMaRns: Length-Based Multispecies Analysis by Numerical Simulation

Description

Calculates the number of individuals of each species in each length class for the next time step.

Usage

calc_growth(N, phi, nfish, nsc)

Arguments

N	A matrix with dimensions nsc and nfish representing the number of individuals in each length class for the current time step.
phi	A matrix with dimensions nsc and nfish representing the proportion of individuals that leave each length class.
nfish	A numeric value representing the number of species in the model.
nsc	A numeric value representing the number of length classes in the model.

Value

A matrix with dimensions nsc and nfish representing the number of individuals of each species in each length class for the next time step.

Examples

# Set up the inputs to the function - species-independent parameters
nfish <- nrow(NS_par)
nsc <- 32
maxsize <- max(NS_par$Linf) * 1.01 # the biggest size is 1% bigger than the largest Linf
l_bound <- seq(0, maxsize, maxsize/nsc); l_bound <- l_bound[-length(l_bound)]
u_bound <- seq(maxsize/nsc, maxsize, maxsize/nsc)
mid <- l_bound+(u_bound-l_bound)/2

# Set up the inputs to the function - species-specific parameters
Linf <- NS_par$Linf # the von-Bertalanffy asymptotic length of each species (cm).
W_a <- NS_par$W_a # length-weight conversion parameter.
W_b <- NS_par$W_b # length-weight conversion parameter.
k <- NS_par$k # the von-Bertalnaffy growth parameter.
Lmat <- NS_par$Lmat # the length at which 50\% of individuals are mature (cm).

# Get phi_min
tmp <- calc_phi(k, Linf, nsc, nfish, u_bound, l_bound, calc_phi_min=FALSE,
                  phi_min=0.1) # fixed phi_min
phi <- tmp$phi
phi_min <- tmp$phi_min

# Calculate growth increments
tmp <- calc_ration_growthfac(k, Linf, nsc, nfish, l_bound, u_bound, mid, W_a, W_b, phi_min)
sc_Linf <- tmp$sc_Linf
wgt <- tmp$wgt

# Get an initial population
N0 <- get_N0(nsc, nfish, mid, wgt, sc_Linf, intercept=1e10, slope=-5)

# Calculate growth
growth <- calc_growth(N0, phi, nfish, nsc)

LeMaRns documentation built on Dec. 9, 2019, 5:09 p.m.