Calculate Effort Multiplier for Harvest Control Rules

Converts a harvest control rule (HCR) fihsing mortality target into a multiplier relative to a (dynamic) reference fishing mortality level.

effort.is(
  stk,
  ctrl,
  Fref = yearMeans(fbar(stk)[, ac(seq(dy - nyears, dy))]),
  nyears = args$nsqy,
  args,
  tracking
)

Arguments

stk: An FLStock object containing stock information
ctrl: A fwdControl object setting an F or effort target.
Fref: Numeric or FLQuant. Reference fishing mortality for scaling. Defaults to the mean of fbar over the specified years.
nyears: Integer. Number of years to use for calculating mean Fref. Default is taken from args$nsqy
args: A list containing dimensionality arguments, passed on by mp().
tracking: An FLQuant used for tracking indicators, intermediate values, and decisions during MP evaluation.

Value

A list containing:

ctrl: Updated control list with effort multiplier in value and adjusted years in rel.year
tracking: Updated tracking object

Details

The function calculates the effort multiplier as: $$mult = \frac{target}{F_{ref}}$$

This multiplier is then stored in the control object with years adjusted backwards by data_lag to account for assessment lag.

Note

The ctrl$quant parameter must be one of "f", "fbar", or "effort". Other values will cause the function to stop with an error.

Examples

# Example dataset
data(plesim)

# Sets up an mpCtrl using hockeystick(fbar~ssb)
ctrl <- mpCtrl(
  est = mseCtrl(method=perfect.sa),
  hcr = mseCtrl(method=hockeystick.hcr, args=list(metric="ssb", trigger=45000, 
    output="fbar", target=0.27)),
  isys = mseCtrl(method=effort.is, args=list(nyears=3)))

# Runs mp between 2021 and 2035
run <- mp(om, control=ctrl, args=list(iy=2021, fy=2035))
#> 2021  - 2022  - 2023  - 2024  - 2025  - 2026  - 2027  - 2028  - 2029  - 2030  - 2031  - 2032  - 2033  - 2034  - 

# Runs mp without effort.is 'nyears' buffer effect
run_nois <- mp(om, control=ctrl[-3], args=list(iy=2021, fy=2035))
#> 2021  - 2022  - 2023  - 2024  - 2025  - 2026  - 2027  - 2028  - 2029  - 2030  - 2031  - 2032  - 2033  - 2034  - 

# Plots results
plot(om, effort.is=run, no_is=run_nois)