ricker_v_t {metafolio}

Ricker stock-recruit function with specified error

Description

Ricker stock-recruit function with specified error

Usage

ricker_v_t(spawners, a, b, d, v_t)

Arguments

spawners

A single spawner abundance

a

Ricker productivity parameter. Recruits are e^a at the origin.

b

Ricker density dependent parameter.

d

Depensation parameter. A value of 1 means no depensation. Larger values indicate depensation.

v_t

A single residual on the curve. Will be exponentiated. Note that we are *not* bias correcting within this function (subtracting half the variance squared) and so the deviations will not be mean unbiased unless they were bias corrected previously.

Value

Returns a vector of recruits.

Examples

plot(1, 1, xlim = c(1, 100), ylim = c(0, 90), type = "n", xlab = "Spawners",
  ylab = "Returns")
for(i in 1:100) {
points(i, ricker_v_t(i, a = 1.1, b = 60, d = 1, v_t = rnorm(1, mean =
  -(0.1^2)/2, sd = 0.1)))
}