Step-wise Constant Catch — LstepCC1 • DLMtool Functions

A management procedure that incrementally adjusts the TAC according to the mean length of recent catches.

Usage

LstepCC1(
  x,
  Data,
  reps = 100,
  plot = FALSE,
  yrsmth = 5,
  xx = 0,
  stepsz = 0.05,
  llim = c(0.96, 0.98, 1.05)
)

LstepCC2(
  x,
  Data,
  reps = 100,
  plot = FALSE,
  yrsmth = 5,
  xx = 0.1,
  stepsz = 0.05,
  llim = c(0.96, 0.98, 1.05)
)

LstepCC3(
  x,
  Data,
  reps = 100,
  plot = FALSE,
  yrsmth = 5,
  xx = 0.2,
  stepsz = 0.05,
  llim = c(0.96, 0.98, 1.05)
)

LstepCC4(
  x,
  Data,
  reps = 100,
  plot = FALSE,
  yrsmth = 5,
  xx = 0.3,
  stepsz = 0.05,
  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 mean length.
xx: Parameter controlling the fraction of mean catch to start using in first year
stepsz: Parameter controlling the size of update increment in TAC or effort.
llim: A vector of length reference points that determine the conditions for increasing, maintaining or reducing the TAC or effort.

Value

An object of class Rec-class with the TAC slot populated with a numeric vector of length reps

Details

The TAC is calculated as: $$\textrm{TAC} = \left\{\begin{array}{ll} \textrm{TAC}^* - 2 S\textrm{TAC}^* & \textrm{if } r < 0.96 \\ \textrm{TAC}^* - S \textrm{TAC}^* & \textrm{if } r < 0.98 \\ \textrm{TAC}^* & \textrm{if } > 1.058 \\ \end{array}\right. $$ where $\textrm{TAC}^*$ is (1-xx) times average catch in the first year, and previous catch in all projection years, $S$ 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

LstepCC1: The least biologically precautionary TAC-based MP.
LstepCC2: More biologically precautionary than LstepCC1 (xx = 0.1)
LstepCC3: More biologically precautionary than LstepCC2 (xx = 0.2)
LstepCC4: The most precautionary TAC-based MP.

Required Data

See Data-class for information on the Data object

LstepCC1: Cat, LHYear, ML, Year

LstepCC2: Cat, LHYear, ML, Year

LstepCC3: Cat, LHYear, ML, Year

LstepCC4: Cat, LHYear, ML, 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

LstepCC1(1, Data=MSEtool::SimulatedData, plot=TRUE)

#> TAC (median) 
#>     2378.001 

LstepCC2(1, Data=MSEtool::SimulatedData, plot=TRUE)

#> TAC (median) 
#>     2151.918 
LstepCC3(1, Data=MSEtool::SimulatedData, plot=TRUE)

#> TAC (median) 
#>     1883.772 
LstepCC4(1, Data=MSEtool::SimulatedData, plot=TRUE)

#> TAC (median) 
#>      1680.32