Age-based catch curve — catch

Regression of \(\log n_a\) on age over the descending limb of the catch-at-age (pooled over the selected years); total mortality \(Z = -\text{slope}\). By default the fit starts one age after the mode and drops the last (plus-group) age.

Usage

catch_curve(
  x,
  species = NULL,
  source = NULL,
  iter = 1,
  years = NULL,
  ages = NULL,
  om = NULL
)

Arguments

x: catch-at-age from caa_obs(), or a floss_data (then caa_obs() is called with species, source, iter, years).
species: species name.
source: fleet for caa_obs().
iter: iteration(s) (pooled).
years: years to use; default all.
ages: ages to include in the regression (default: descending limb).
om: optional floss_om of the species: adds the true mean Z over the fitted ages and years.

Value

a floss_fit with pars (Z) and, when the true M is known, F = Z - M.