Segmented harvest control rules

Source: R/HCRs.R

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.

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.

Value

An object of class Rec with the TAC recommendation.

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 Asesssment@forecast[["per_recruit"]].

  • "F_FSPR": Fishing mortality relative to F_SPR "SPR_OCP", calculated from the data frame in Asesssment@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 Asesssment@forecast[["per_recruit"]].

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

  • "FSPR": Fishing mortality relative to F_SPR "SPR_targ", calculated from data frame in Asesssment@forecast[["per_recruit"]].

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

Author

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))