invl {MQMF}

invl calculates growth increments for the inverse logistic

Description

invl requires at least three parameters, MaxDL, L50, and delta, in a vector, as well as the initial length and the change in time between tag release and recapture. Given those it calculates the expected growth increment according to the inverse logistic curve. The parameter delta is equivalent to L95 - L50, the length difference between the length at half MaxDL, and the length at 5

Usage

invl(par, indat, initL = "l1", delT = "dt")

Arguments

par

a vector of at least MaxDL, L50, and delta from the inverse logistic growth curve

indat

the matrix or data.frame of data columns containing at least the initial lengths and the deltaT, time intervals between tag release and recapture.

initL

column name of the initial lengths within indat, default="l1"

delT

column name of the time interval, deltaT, within indat, default="dt"

Value

a vector of predicted growth increments

References

Haddon, M., Mundy, C., and D. Tarbath (2008) Using an inverse-logistic model to describe growth increments of blacklip abalone (Haliotis rubra) in Tasmania. Fishery Bulletin 106:58-71

Examples

 data(blackisland)
 oldpar <- par(no.readonly=TRUE)
 plot(blackisland$l1,blackisland$dl,type="p",pch=16,
 xlab="Initial Length mm",ylab="Growth Increment mm",panel.first=grid())
 abline(h=0)
 param <- c(25, 130, 35, 3) # MaxDL, L50, delta, sigma
 predDL <- invl(param,blackisland,initL="l1",delT="dt")
 lines(blackisland$l1,predDL,col=2,lwd=2) 
 par(oldpar)