HCR_escapement: Fixed escapement harvest control rule

In SAMtool: Stock Assessment Methods Toolkit

Fixed escapement harvest control rule

Description

A simple control rule that allows fishing when the operational control point (OCP) is above some threshold. By default, this function sets the TAC at F = 100% FMSY when spawning depletion > 0.1.

Usage

HCR_escapement(
  Assessment,
  reps = 1,
  OCP_type = "SSB_SSB0",
  OCP_threshold = 0.2,
  Ftarget_type = "FMSY",
  relF_max = 1,
  ...
)

Arguments

Assessment	An object of class Assessment with estimates of FMSY or UMSY and vulnerable biomass in terminal year.
reps	The number of stochastic samples of the TAC recommendation.
OCP_type	The type of operational control points (OCPs) for the harvest control rule used to determine whether there is fishing. By default, use ("SSB_SSB0" for spawning depletion. Other biomass OCPs include "SSB_SSBMSY" for spawning biomass relative to MSY and "SSB_dSSB0", for dynamic depletion (dynamic SSB0 is the historical reconstructed biomass with F = 0). For F-based OCPs, the terminal year fishing mortality relative F01 or Fmax (using yield-per-recruit) or F-SPR% (see SPR_OCP argument) can be used.
OCP_threshold	The value of the OCP above which fishing can occur.
Ftarget_type	The type of F used for the target fishing mortality rate.
relF_max	The relative value of Ftarget if OCP > OCP_treshold.
...	Miscellaneous arguments.

Details

The catch advice is calculated using the catch equation of the corresponding assessment. See Assessment@forecast$catch_eq, a function that returns the catch advice for a specified Ftarget.

Value

An object of class Rec with the TAC recommendation.

Author(s)

Q. Huynh

References

Deroba, J.J. and Bence, J.R. 2008. A review of harvest policies: Understanding relative performance of control rules. Fisheries Research 94:210-223.

See Also

make_MP HCR_ramp

Examples

# create an MP to run in closed-loop MSE (fishes at FMSY when B/B0 > 0.2)
SP_escapement <- make_MP(SP, HCR_escapement)

# The MP which fishes at 75% of FMSY
SP_escapement75 <- make_MP(SP, HCR_escapement, relF_max = 0.75)

# The MP which fishes at FMSY when BMSY > 0.5
SP_BMSY_escapement <- make_MP(SP, HCR_escapement, OCP_type = "SSB_SSBMSY", 
                              OCP_threshold = 0.5, relF_max = 1)


myOM <- MSEtool::runMSE(MSEtool::testOM, MPs = c("FMSYref", "SP_escapement", "SP_BMSY_escapement"))

SAMtool documentation built on Nov. 18, 2023, 9:07 a.m.