Ltarget1 {DLMtool} | R Documentation |
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-class
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-class
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=MSEtool::SimulatedData, plot=TRUE) Ltarget2(1, Data=MSEtool::SimulatedData, plot=TRUE) Ltarget3(1, Data=MSEtool::SimulatedData, plot=TRUE) Ltarget4(1, Data=MSEtool::SimulatedData, plot=TRUE) L95target(1, Data=MSEtool::SimulatedData, plot=TRUE)