`Islope1.Rd`

A management procedure that incrementally adjusts the TAC to maintain a constant CPUE or relative abundance index.

Islope1(x, Data, reps = 100, plot = FALSE, yrsmth = 5, lambda = 0.4, xx = 0.2) Islope2(x, Data, reps = 100, plot = FALSE, yrsmth = 5, lambda = 0.4, xx = 0.3) Islope3(x, Data, reps = 100, plot = FALSE, yrsmth = 5, lambda = 0.4, xx = 0.4) Islope4(x, Data, reps = 100, plot = FALSE, yrsmth = 5, lambda = 0.2, xx = 0.4)

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 index |

lambda | A gain parameter controlling the speed in update in TAC. |

xx | Parameter controlling the fraction of mean catch to start using in first year |

An object of class `Rec-class`

with the `TAC`

slot populated with a numeric vector of length `reps`

The TAC is calculated as:
$$\textrm{TAC} = \textrm{TAC}^* \left(1+\lambda I \right)$$
where \(\textrm{TAC}^*\) is \(1-xx\) multiplied by the mean catch from the past `yrsmth`

years for the
first year and catch from the previous year in projection years,
\(\lambda\) is a gain parameter, and \(I\) is the slope of log index over the past `yrsmth`

years.

`Islope1`

: The least biologically precautionary of the Islope methods`Islope2`

: More biologically precautionary. Reference TAC is 0.7 average catch`Islope3`

: More biologically precautionary. Reference TAC is 0.6 average catch`Islope4`

: The most biologically precautionary of the Islope methods. Reference TAC is 0.6 average catch and gain parameter is 0.2

See `Data-class`

for information on the `Data`

object

`Islope1`

: Cat, Ind, LHYear, Year

See Online Documentation for correctly rendered equations

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 Index methods:
`GB_slope()`

,
`GB_target()`

,
`Gcontrol()`

,
`ICI()`

,
`Iratio()`

,
`Itarget1_MPA()`

,
`Itarget1()`

,
`ItargetE1()`

T. Carruthers

#> TAC (median) #> 1204.367#> TAC (median) #> 1206.411#> TAC (median) #> 1208.76#> TAC (median) #> 1255.617