The MP adjusts catch based on the value of the index in the current year relative to the time series mean and standard error. 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 (see Jardim et al. 2015).
ICI2(x, Data, reps)A position in data-limited methods data object
A data-limited methods data object
The number of TAC samples
The mean and standard error of the index time series is calculated. There are two thresholds which delineates whether catch is reduced, held constant, or increased. 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.
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