VBGF | R Documentation |
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.
VBGF(param, t = NA, L = NA, na.rm = FALSE)
param |
a list with following potential objects:
|
t |
ages for which to calculate corresponding lengths, or |
L |
lengths for which to calculate corresponding ages |
na.rm |
logical; should NA in input length or age vector be omitted? (default: FALSE) |
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), 8-11
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.
# 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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