Step-wise Constant Effort

A management procedure that incrementally adjusts the total allowable effort (TAE) according to the mean length of recent catches.

Usage

LstepCE1(
  x,
  Data,
  reps = 100,
  plot = FALSE,
  yrsmth = 5,
  stepsz = 0.05,
  llim = c(0.96, 0.98, 1.05)
)

LstepCE2(
  x,
  Data,
  reps = 100,
  plot = FALSE,
  yrsmth = 5,
  stepsz = 0.1,
  llim = c(0.96, 0.98, 1.05)
)

Arguments

x: A position in the data object
Data: A data object
reps: The number of stochastic samples of the MP recommendation(s)
plot: Logical. Show the plot?
yrsmth: Years over which to calculate trend in mean length.
stepsz: Parameter controlling the size of update increment in effort.
llim: A vector of length reference points that determine the conditions for increasing, maintaining or reducing the effort.

Value

An object of class Rec-class with the TAE slot(s) populated

Details

The TAE is calculated as: $$\textrm{TAE} = \left\{\begin{array}{ll} \textrm{TAE}^* - 2 S\textrm{TAE}^* & \textrm{if } r < 0.96 \\ \textrm{TAE}^* - S \textrm{TAE}^* & \textrm{if } r < 0.98 \\ \textrm{TAE}^* & \textrm{if } > 1.058 \\ \end{array}\right. $$ where $\textrm{TAE}^*$ is effort in the previous year, $S$ is step-size determined by stepsz, and $r$ is the ratio of $L_\textrm{recent}$ and $L_\textrm{ave}$ which are mean length over the most recent yrsmth years and 2 x yrsmth historical years respectively.

The conditions are specified in the llim argument to the function.

Functions

LstepCE1: The least biologically precautionary effort-based MP.
LstepCE2: Step size is increased to 0.1

Required Data

See Data-class for information on the Data object

LstepCE1: LHYear, ML, MPeff, Year

Rendered Equations

See Online Documentation for correctly rendered equations

References

Carruthers et al. 2015. Performance evaluation of simple management procedures. ICES J. Mar Sci. 73, 464-482.

Geromont, H.F., Butterworth, D.S. 2014. Generic management procedures for data-poor fisheries; forecasting with few data. ICES J. Mar. Sci. doi:10.1093/icesjms/fst232

Author

T. Carruthers

Examples

LstepCE1(1, Data=MSEtool::SimulatedData, plot=TRUE)
#> Effort 
#>      1 
LstepCE2(1, Data=MSEtool::SimulatedData, plot=TRUE)

#> Effort 
#>      1