constrain: Constrain mixed-stock harvest

In CamFreshwater/samSim: Closed-loop salmon dynamics simulator

Constrain mixed-stock harvest

Description

This function asseses whether mixed stock fisheries should be constrained based on the abundance of co-migrating stocks. This process is modeled on the current total allowable mortality rule used to manage Fraser River sockeye salmon fisheries and is not a universal function.

Usage

constrain(rec, highFRP, manAdjustment, manUnit)

Arguments

rec	A numeric vector representing MU-specific return abundance.
highFRP	A numeric vector representing MU-specific upper fishery reference points. When return abundance is above this value _adjacent_ MUs do not need to be constrained.
manAdjustment	A numeric vector representing MU-specific management adjustments. These values are used to adjust spawner abundance to account for en route mortality (i.e. they increase the target escapement goal).
manUnit	A character vector identifying the MU that each CU belongs to.

Details

Total allowable catch (TAC) is set as a function of estimated abundance at the management unit level. A given MU's TAC is constrained unless all MUs with adjacent migration phenologies are above their upper fishery reference point. Note that estimates of TAC and the application of any constraints occurs in calcTAC function.

**Note** Although all input vectors have length equal to nCU, the number of unique values will be equal to nMU because this is the scale at which in-season forecasts are available.

**Note** Originally formatted with forecasted abundance but replaced with true to avoid inflating outcome uncertainty.

Value

Returns a two-element list of binary vectors. In muAboveFRP ones represent MUs with return abundance above their FRP after incorporating management adjustments. In muConstrained ones represent MUs that should be constrained based on the abundance of _adjacent_ MUs.

Examples

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

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

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