MSEtool (version 2.0.1)

HCR_ramp: Linearly ramped harvest control rules

Description

An output control rule with a ramp that reduces the TAC recommendation linearly with respect to fishing mortality (F) or harvest rate (U) when the relative biomass (i.e., spawning depletion or spawning biomass relative to that at MSY) is less than the target reference point (TRP). The TAC reduction is linearly reduced with respect to F to a minimum value when the relative biomass is less than the limit reference point (LRP). For example, the TRP and LRP for spawning depletion is 0.4 and 0.1, respectively, in the 40-10 control rule. Class HCR objects are typically used with function make_MP.

Usage

HCR_ramp(
  Assessment,
  reps = 1,
  LRP,
  TRP,
  rel_min = 0,
  rel_max = 1,
  RP_type = c("SSB_SSB0", "SSB_SSBMSY"),
  ...
)
HCR40_10(Assessment, reps = 1, ...)
HCR60_20(Assessment, reps = 1, ...)

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.

LRP

Numeric, the limit reference point.

TRP

Numeric, the target reference point.

rel_min

The relative maximum value (e.g. a multiple of FMSY) if Brel < LRP.

rel_max

The relative maximum value (e.g. a multiple of FMSY) if Brel > TRP.

RP_type

The reference point metric for TRP and LRP ("SSB_SSB0" for spawning depletion by default, or "SSB_SSBMSY" for spawning biomass relative to MSY).

...

Miscellaneous arguments.

Value

An object of class '>Rec with the TAC recommendation.

Details

HCR_ramp is the generic ramped-HCR function where user specifies LRP, TRP, and relative biomass metric, as well as minimum and maximum values for adjusting the fishing mortality.

HCR40_10 is a common U.S. west coast control rule (LRP and TRP of 0.1 and 0.4 spawning depletion, respectively), while HCR60_20 is more conservative than 40-10, with LRP and TRP of 0.2 and 0.6 spawning depletion, respectively).

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.

Edwards, C.T.T. and Dankel, D.J. (eds.). 2016. Management Science in Fisheries: an introduction to simulation methods. Routledge, New York, NY. 460 pp.

Punt, A. E, Dorn, M. W., and Haltuch, M. A. 2008. Evaluation of threshold management strategies for groundfish off the U.S. West Coast. Fisheries Research 94:251-266.

Restrepo, V.R. and Power, J.E. 1999. Precautionary control rules in US fisheries management: specification and performance. ICES Journal of Marine Science 56:846-852.

See Also

HCR_MSY HCRlin make_MP

Examples

# NOT RUN {
# 40-10 linear ramp
Brel <- seq(0, 1, length.out = 200)
plot(Brel, HCRlin(Brel, 0.1, 0.4), xlab = "Estimated SSB/SSB0",
ylab = "Prescribed F relative to FMSY", main = "40-10 harvest control rule",
type = "l", col = "blue")
abline(v = c(0.1, 0.4), col = "red", lty = 2)

# create a 40-10 MP to run in closed-loop MSE
DD_40_10 <- make_MP(DD_TMB, HCR40_10)

# Alternatively,
DD_40_10 <- make_MP(DD_TMB, HCR_ramp, LRP = 0.1, TRP = 0.4)

# An SCA with LRP and TRP at 0.4 and 0.8, respectively, of SSB/SSBMSY
SCA_80_40 <- make_MP(SCA, HCR_ramp, LRP = 0.4, TRP = 0.8, RP_type = "SSB_SSBMSY")

# A conservative HCR that fishes at 75% of FMSY at B > 80% BMSY but only reduces F
# to 10% of FMSY if B < 40% BMSY.
SCA_conservative <- make_MP(SCA, HCR_ramp, LRP = 0.4, TRP = 0.8, rel_max = 0.75,
rel_min = 0.1, RP_type = "SSB_SSBMSY")

# Figure of this conservative HCR
Brel <- seq(0, 1, length.out = 200)
Frel <- HCRlin(Brel, 0.4, 0.8, rel_max = 0.75, rel_min = 0.1)
plot(Brel, Frel, xlab = "Estimated SSB/SSB_MSY", ylab = "Prescribed F relative to FMSY",
type = "l", col = "blue")
abline(v = c(0.4, 0.8), col = "red", lty = 2)

# }
# NOT RUN {
myOM <- DLMtool::runMSE(DLMtool::testOM, MPs = c("FMSYref", "DD_40_10"))
# }