Estimate depletion under alternative fishing mortalities
est.depletion.Rd`est.depletion()` evaluates the depletion level (typically biomass relative to unfished biomass, \(B/B_0\), or a related quantity) for a range of fishing mortalities. The function simulates the IAMSE operating model over a grid of fishing mortality values between `fmin` and `fmax`, using `nrep` stochastic replicates, and summarises the resulting depletion distribution according to the chosen `method`.
Usage
est.depletion(
dat,
set = NULL,
fmin = 1e-04,
fmax = 10,
nrep = 100,
verbose = TRUE,
method = "percentile",
B0K = FALSE,
tol = 1e-04,
do.opt = TRUE
)Arguments
- dat
Data object as returned by [check.dat()], containing life-history and stock information for the operating model.
- set
Optional settings list as returned by [check.set()]. If `NULL` (default), internal defaults are used where possible. When supplied, `set` controls aspects such as the number of years, projection horizon, and noise structure.
- fmin
Numeric value giving the minimum fishing mortality (or F-multiplier) considered in the depletion calculation. Default is `0.0001`.
- fmax
Numeric value giving the maximum fishing mortality considered in the depletion calculation. Default is `10`.
- nrep
Integer specifying the number of stochastic replicates used for each fishing mortality level. Larger values give more stable depletion estimates at the cost of increased computation time. Default is `100`.
- verbose
Logical; if `TRUE`, print progress messages and basic diagnostics during the calculation. Default is `TRUE`.
- method
Character string indicating how the depletion distribution is summarised across replicates. The default `"percentile"` typically uses quantiles of the simulated depletion distribution. Other methods may be available depending on the internal implementation.
- B0K
Logical; if `TRUE`, treat the carrying capacity \(K\) as equivalent to unfished biomass \(B_0\) when computing depletion. If `FALSE` (default), \(B_0\) is used explicitly if available.
- tol
Numeric tolerance used in any optimisation or root-finding procedures (e.g. when solving for the fishing mortality associated with a target depletion level). Default is `0.0001`.
- do.opt
Logical; if `TRUE` (default), perform optimisation to identify fishing mortality values corresponding to target depletion levels. If `FALSE`, the function only evaluates depletion over the grid defined by `fmin` and `fmax` without attempting to optimise.
Value
An object (typically a list or data frame) summarising depletion as a function of fishing mortality, including summary statistics across replicates. The exact structure depends on the internal implementation. The object is returned invisibly if the function is mainly used for its side effects (e.g. storing results in `dat`).