Ltarget1: Length Target TAC MP
In DLMtool/DLMtool: Data-Limited Methods Toolkit

Description Usage Arguments Details Value Functions Required Data Rendered Equations Author(s) References See Also Examples

View source: R/MPs_Output.R

A management procedure that incrementally adjusts the TAC to reach a target mean length in catches.

Ltarget1(x, Data, reps = 100, plot = FALSE, yrsmth = 5, xx = 0, xL = 1.05)

Ltarget2(x, Data, reps = 100, plot = FALSE, yrsmth = 5, xx = 0, xL = 1.1)

Ltarget3(x, Data, reps = 100, plot = FALSE, yrsmth = 5, xx = 0, xL = 1.15)

Ltarget4(x, Data, reps = 100, plot = FALSE, yrsmth = 5, xx = 0.2, xL = 1.15)

L95target(x, Data, reps = 100, plot = FALSE, yrsmth = 5, xx = 0, xL = 1.05)

`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
`xL`	Parameter controlling the magnitude of the target mean length of catches relative to average length in catches.

Four target length MPs proposed by Geromont and Butterworth 2014. Tested by Carruthers et al. 2015.

The TAC is calculated as:

If L_\textrm{recent} ≥q L_0:

\textrm{TAC} = 0.5 \textrm{TAC}^* ≤ft[1+≤ft(\frac{L_\textrm{recent}-L_0}{L_\textrm{target}-L_0}\right)\right]

else:

\textrm{TAC} = 0.5 \textrm{TAC}^* ≤ft[\frac{L_\textrm{recent}}{L_0}^2\right]

where \textrm{TAC}^* is (1 - xx) mean catches from the last yrsmth historical years (pre-projection), L_\textrm{recent} is mean length in last yrmsth years, L_0 is (except for L95target) 0.9 average catch in the last 2 x yrsmth historical (pre-projection years) (L_\textrm{ave}), and L_\textrm{target} is (except for L95target) xL L_\textrm{ave}.

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

Ltarget1: The least biologically precautionary TAC-based MP.
Ltarget2: Increasingly biologically precautionary (xL = 1.1).
Ltarget3: Increasingly biologically precautionary (xL = 1.1).
Ltarget4: The most biologically precautionary TAC-based MP (xL = 1.1, xx=0.2).
L95target: Same as Ltarget1 but here the target and limit mean lengths are based on the length at maturity distribution rather than an arbitrary multiplicative of the mean length

See Data for information on the Data object

Ltarget1: Cat, LHYear, ML, Year

Ltarget2: Cat, LHYear, ML, Year

Ltarget3: Cat, LHYear, ML, Year

Ltarget4: Cat, LHYear, ML, Year

L95target: Cat, L50, LHYear, ML, Year

See Online Documentation for correctly rendered equations

T. Carruthers

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

Other Length target MPs: Lratio_BHI(), LtargetE1()

Ltarget1(1, Data=DLMtool::SimulatedData, plot=TRUE)
Ltarget2(1, Data=DLMtool::SimulatedData, plot=TRUE)
Ltarget3(1, Data=DLMtool::SimulatedData, plot=TRUE)
Ltarget4(1, Data=DLMtool::SimulatedData, plot=TRUE)
L95target(1, Data=DLMtool::SimulatedData, plot=TRUE)