Description Usage Arguments Details Value References Examples
This function applies the von Bertalanffy growth function (VBGF). It allows to calculate ages from lengths or lengths from ages based on the special, generalised or seasonalised VBGF.
1 
param 
a list with following potential objects:

t 
ages for which to calculate corresponding lengths, or 
L 
lengths for which to calculate corresponding ages 
Based upon which input parameters are given one of the following VBGF types is applied: "special", "generalised", or "seasonalised" VBGF.
A vector with estimated lengths corresponding to provided ages.
Somers, I. F. (1988). On a seasonally oscillating growth function. Fishbyte, 6(1), 811
Sparre, P., Venema, S.C., 1998. Introduction to tropical fish stock assessment. Part 1. Manual. FAO Fisheries Technical Paper, (306.1, Rev. 2). 407 p.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26  # calculation of lengths
# with t0
t < seq(0,6,0.1)
Lt < VBGF(list(Linf=80, K=0.6, t0=0.1),t=t)
plot(t, Lt, t="l")
# with L0
t < seq(0,6,0.1)
Lt < VBGF(list(Linf=80, K=0.6, L0=2),t=t)
plot(t, Lt, t="l")
# with Winf
t < seq(0,6,0.1)
Wt < VBGF(list(Winf=4000, K=0.8), t=t)
plot(t, Wt, t="l")
# seasonalised VBGF
t < seq(0,6,0.1)
Lt < VBGF(list(Linf=80, K=0.6, t0=0.1, ts=0.5, C=0.75),t=t)
plot(t, Lt, t="l")
# calculation of ages
L < seq(2,200,0.1)
t < VBGF(L = L, list(Linf=210, K=0.8, C= 0.75))
plot(t, L, t="l")

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