The five-parameter growth function from Schnute and Richards (1990).

The five-parameter growth function from Schnute and Richards (1990). Note that this function is slightly modified (a ‘+’ was changed to a ‘-’ so that the ‘a’ parameter will be positive) from the original in Schnute and Richards (1990)

Usage

SchnuteRichards(t, Linf = NULL, k = NULL, a = NULL, b = NULL, c = NULL)

Arguments

t

A numeric vector of ages over which to model growth.

Linf

Mean asymptotic length.

k

The "growth coefficient" with units of (year^(-c)).

a

A dimensionless parameter

b

A dimensionless parameter.

c

A dimensionless parameter.

Value

SchnuteRichards returns a predicted size given the provided parameter values.

IFAR Chapter

None specifically, but 12-Individual Growth is related.

References

Schnute, J.T. and L.J. Richards. 1990. A unified approach to the analysis of fish growth, maturity, and survivorship data. Canadian Journal of Fisheries and Aquatic Sciences. 47:24-40.

See also

See vbFuns, GompertzFuns, RichardsFuns, logisticFuns, and Schnute for similar functionality for other models.

Author

Derek H. Ogle, DerekOgle51@gmail.com

Examples

## See the formulae
growthFunShow("SchnuteRichards",plot=TRUE)

#> expression(E(L[t]) == L[infinity] * ~bgroup("(", 1 - a * e^{
#>     -kt^{
#>         c
#>     }
#> }, ")")^{
#>     frac(1, b)
#> })

## Simple examples
ages <- 1:15
s1 <- SchnuteRichards(ages,Linf=100,k=0.03,a=0.01,b=0.005,c=2)
plot(s1~ages,type="l",lwd=2)