`ICI.Rd`

The MP adjusts catch based on the value of the index in the current year relative to the time series mean and standard error.

ICI(x, Data, reps = 100, plot = FALSE) ICI2(x, Data, reps = 100, plot = FALSE)

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? |

An object of class `Rec-class`

with the `TAC`

slot populated with a numeric vector of length `reps`

The TAC is calculated as:
$$\textrm{TAC}_y=C_{y-1} \alpha$$
where \(C_{y-1}\) is the catch from the previous year, and \(\alpha\) is
defined as:
$$\alpha =
\left\{\begin{array}{ll}
d & \textrm{if } I < \textrm{CI}_L \\
u & \textrm{if } I > \textrm{CI}_H \\
1 & \textrm{if } \textrm{CI}_L \leq I \leq \textrm{CI}_H \\
\end{array}\right.
$$
where \(I\) is the index in the most recent year, \(d\) is 0.75 for `ICI`

and `ICI2`

,
\(u\) is 1.05 and 1.25 for`ICI`

and `ICI2`

respectively, and \(\textrm{CI}_L\)
and \(\textrm{CI}_L\) are the lower and upper bound of the confidence
interval of mean historical index. The confidence interval is
calculated using Z-scores described in the Functions section below.

`ICI`

: The catch is reduced by 0.75 if the Z-score of the current year's index is less than -0.44. The catch is increased by 1.05 if the Z-score of the current year's index is greater than 1.96. Otherwise, the catch is held constant.`ICI2`

: This method is less precautionary of the two ICI MPs by allowing for a larger increase in TAC and a lower threshold of the index to decrease the TAC. The catch is reduced by 0.75 if the Z-score of the current year's index is less than -1.96. The catch is increased by 1.25 if the Z-score of the current year's index is greater than 1.96. Otherwise, the catch is held constant.

See `Data-class`

for information on the `Data`

object

`ICI`

: Cat, Ind

`ICI2`

: Cat, Ind

See Online Documentation for correctly rendered equations

Ernesto Jardim, Manuela Azevedo, Nuno M. Brites, Harvest control rules for data limited stocks using length-based reference points and survey biomass indices, Fisheries Research, Volume 171, November 2015, Pages 12-19, ISSN 0165-7836, https://doi.org/10.1016/j.fishres.2014.11.013

Other Index methods:
`GB_slope()`

,
`GB_target()`

,
`Gcontrol()`

,
`Iratio()`

,
`Islope1()`

,
`Itarget1_MPA()`

,
`Itarget1()`

,
`ItargetE1()`

Coded by Q. Huynh. Developed by Jardim et al. (2015)

#> TAC (median) #> 13.58889#> TAC (median) #> 13.81198