calcTAC: Calculate total allowable catch

In CamFreshwater/samSim: Closed-loop salmon dynamics simulator

Calculate total allowable catch

Description

This function calculates total allowable catch (TAC) for different MUs using either a) a fixed exploitation rate, b) a simplified version of the total allowable mortality (TAM) rule currently used to manage the Fraser sockeye fishery, or c) a generic HCR that is consistent with the precautionary approach (genPA). TAC is divided between one American and two Canadian fisheries (mixed stock and single stock) based on ppnMix variable.

Usage

calcTAC(
  rec,
  canER,
  harvContRule,
  amER,
  ppnMixVec,
  manAdjustment = NULL,
  lowFRP = NULL,
  highFRP = NULL,
  minER = NULL,
  maxER = NULL,
  overlapConstraint = NULL,
  constrainMix = TRUE
)

Arguments

rec	A numeric representing MU-specific return abundance.
canER	A numeric representing the target Canadian exploitation rate if harvContRule = fixedER
harvContRule	A character signifying whether TACs are based on a fixed exploitation rate (fixedER) or the simplified TAM rule (TAM).
amER	A numeric representing the target American exploitation rate. **Note** that American catch is a function of TAC not escapement for Fraser sockeye and takes into account the Aboriginal Fishery Exclusion (400k fish). Thus their catch/harvest rate is generally below the input parameter.
manAdjustment	A numeric representing MU-specific management adjustments. These values are used to adjust forecasted spawner abundance to account for en route mortality (i.e. they increase the target escapement goal).
lowFRP	A numeric representing a MU-specific lower fishery reference point.
highFRP	A numeric vector a MU-specific upper fishery reference point.
minER	A numeric representing minimum exploitation rate (intended to represent mortality due to bycatch or test fisheries).
maxER	A numeric representing maximum exploitation rate that is applied when MU is above its higher FRP.
overlapConstraint	A numeric representing whether a given MU's TAC should be constrained or not.
ppnMix	A numeric representing the proportion of the Canadian TAC allocated to mixed stock fisheries.

Details

In the case of the TAM rules TAC is based on abundance relative to two fishery reference points, which determines whether exploitation is based on a minimum exploitation rate, fixed escapement goal, or maximum exploitation rate. Note that abundance relative to reference points is adjusted downwards to account for anticipated en route mortality (manAdjustment). TAC will be further reduced based on overlapConstraint which represents whether other MUs that co-migrate are at sufficiently low abundance to limit a given fishery (see overlapConstraint for additional details).

In the case of the genPA rule TAC is also based on abundance relative to two fishery reference points, but there is no management adjustment or overlap constraint. When abundance is below the lower FRP min ER is applied, between the two it increases linearly, and above it is max (typically Umsy).

Value

Returns a six element list of numeric vectors with length equal to forecast: American TAC, single fishery TAC, mixed fishery TAC, total TAC, unconstrained American TAC, and unconstrained Canadian TAC (latter two for reference purposes only).

Examples

#Note that the function is intended to receive vectors rather than the DF
#used in this example to increase efficiency within the full closed-loop
simulation.
head(exampleHCRList)
names(exampleHCRList)[4] <- "recRYMU"

rec <- exampleHCRList$recRYMU
lowFRP <- exampleHCRList$lowFRP
highFRP <- exampleHCRList$highFRP
manAdjustment <- exampleHCRList$adjustment
manUnit <- exampleHCRList$mu
overlapConstraint <- constrain(rec, highFRP, manAdjustment,
                               manUnit)$muConstrained

## Fixed ER version
calcTAC(rec, canER = 0.4, harvContRule = "fixedER", amER = 0.1, ppnMix = 1)
## TAM version
calcTAC(rec, canER, harvContRule = "TAM", amER = 0.1, ppnMix = 1,
        manAdjustment = manAdjustment, lowFRP = lowFRP,
        highFRP = highFRP,  minER = 0.1, maxER = 0.6,
        overlapConstraint = overlapConstraint)

CamFreshwater/samSim documentation built on Sept. 25, 2023, 10:22 a.m.