SRR with environmental variables

[Isabella84]

Hi Colin, may I ask if Eqsim can estimate SRR including environmental variables? From the code I see only 4 models, isn'it? Many thanks, Isabella

[colinpmillar]

Hi Isabella, yes it is limited to 2 or 1 parameter stock assessment models, you can write your own and supply it, and it needs to be of the form:

my_srmod <- 
function (ab, ssb)
{
    ...
}

where the object ab, is an object with an element ab$a and ab$b. and it predicts log recriuts i.e.

Ricker <-
function (ab, ssb)
{
    log(ab$a) + log(ssb) - ab$b * ssb
}

or

Segreg <-
function (ab, ssb)
{
    log(ifelse(ssb >= ab$b, ab$a * ab$b, ab$a * ssb))
}

I am not sure if you can 'shoe horn' environmental covariates into this structure.... probably not without some changes to the package code.

Thanks, Colin