HCR_segment: Segmented harvest control rules

In SAMtool: Stock Assessment Methods Toolkit

Segmented harvest control rules

Description

A linear segmented output control rule where the target F (used for the TAC recommendation) is a function of an operational control point (OCP) such as spawning depletion or spawning biomass. The segments of the HCR are specified by arguments OCP and relF. Beyond the range of OCP, the response will be flat. HCR_ramp uses HCR_segment with two control points.

Usage

HCR_segment(
  Assessment,
  reps = 1,
  OCP_type = c("SSB_SSB0", "SSB_SSBMSY", "SSB_dSSB0", "F_FMSY", "F_F01", "F_FSPR"),
  Ftarget_type = c("FMSY", "F01", "Fmax", "FSPR", "abs"),
  OCP = c(0.1, 0.4),
  relF = c(0, 1),
  SPR_OCP,
  SPR_targ,
  ...
)

Arguments

Assessment	An object of class Assessment with estimates of FMSY or UMSY, vulnerable biomass, and spawning biomass depletion 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 the reduction in F. See below.
Ftarget_type	The type of F used for the target fishing mortality rate. See below.
OCP	Numeric vector of operational control points for the HCR (in increasing order).
relF	Numeric vector of Ftarget corresponding to the values in OCP.
SPR_OCP	The value of spawning potential ratio for the OCP if OCP_type = "F_FSPR". By default, 0.4 (F40%).
SPR_targ	The target value of spawning potential ratio if Ftarget_type = "FSPR". By default, 0.4 (F40%).
...	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.

Operational control points (OCP_type)

The following are the available options for harvest control rule inputs, and the source of those values in the Assessment object:

• Default "SSB_SSB0": Spawning depletion. Uses the last value in Assessment@SSB_SSB0 vector.

• "SSB_SSBMSY": Spawning biomass relative to MSY. Uses the last value in Assessment@SSB_SSBMSY vector.

• "SSB_dSSB0": Dynamic depletion (SSB relative to the historical reconstructed biomass with F = 0). Uses the last value in Assessment@SSB/Assessment@TMB_report$dynamic_SSB0.

• "F_FMSY": Fishing mortality relative to MSY. Uses the last value in Assessment@F_FMSY.

• "F_F01": Fishing mortality relative to F_0.1 (yield per recruit), calculated from the data frame in Assessment@forecast[["per_recruit"]].

• "F_FSPR": Fishing mortality relative to F_SPR% (the F that produces the spawning potential ratio specified in "SPR_OCP", calculated from the data frame in Assessment@forecast[["per_recruit"]].

Fishing mortality target (Ftarget_type)

The type of F for which the corresponding catch is calculated in the HCR is specified here. The source of those values in the Assessment object is specified:

• Default "FMSY": Fishing mortality relative to MSY. Uses the value in Assessment@FMSY.

• "F01": Fishing mortality relative to F_0.1 (yield per recruit), calculated from the data frame in Assessment@forecast[["per_recruit"]].

• "Fmax": Fishing mortality relative to F_max (maximizing yield per recruit), calculated from the data frame in Assessment@forecast[["per_recruit"]].

• "FSPR": Fishing mortality relative to F_SPR% (the F that produces the spawning potential ratio specified in "SPR_targ", calculated from data frame in Assessment@forecast[["per_recruit"]].

• "abs": Fishing mortality is independent of any model output and is explicitly specified in relF.

Value

An object of class MSEtool::Rec with the TAC recommendation.

Author(s)

Q. Huynh

Examples

# This is an MP with a 40-10 harvest control rule (using FMSY)
DD_40_10 <- make_MP(DD_TMB, HCR_segment, OCP_type = "SSB_SSB0", OCP = c(0.1, 0.4), relF = c(0, 1)) 
#' 
# This is an MP with a 40-10 harvest control rule with a maximum F of 0.1
DD_40_10 <- make_MP(DD_TMB, HCR_segment, OCP_type = "SSB_SSB0", 
                    Ftarget_type = "abs", OCP = c(0.1, 0.4), relF = c(0, 0.1)) 

SAMtool documentation built on Sept. 11, 2024, 8:07 p.m.