# Harvest control rule to fish at some fraction of maximum sustainable yield

Source:`R/HCRs.R`

`HCR_MSY.Rd`

A simple control rule that specifies the total allowable catch (TAC) as a function of the abundance of the first projection year and some fraction of FMSY/UMSY.

## Arguments

- Assessment
An object of class Assessment with estimates of FMSY or UMSY and vulnerable biomass in terminal year.

- reps
The number of stochastic samples of the TAC recommendation.

- MSY_frac
The fraction of FMSY or UMSY for calculating the TAC (e.g. MSY_frac = 0.75 fishes at 75% of FMSY).

- ...
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`

.

## References

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.

## Examples

```
# create an MP to run in closed-loop MSE (fishes at UMSY)
SPMSY <- make_MP(SP, HCR_MSY)
# The MP which fishes at 75% of FMSY
SP75MSY <- make_MP(SP, HCR_MSY, MSY_frac = 0.75)
# \donttest{
myOM <- MSEtool::runMSE(MSEtool::testOM, MPs = c("FMSYref", "SPMSY", "SP75MSY"))
#> ✔ Checking MPs
#> Error: Some MPs are not a functions of class `MP`: SPMSY, SP75MSY
# }
```