The last full assessment for the 3M Cod in the NAFO Scientific Council was carried out in June 2015, giving an advice for two years. Some problems concerning the NAFO 3M cod projections were identified during the 2015 Annual Meeting. Trying to solve these issues, a Workshop was organized by the EU in March 2017.
An issue raised by the Fisheries Commission in 2015 is that the risk of exceeding Flim for some of the projection scenarios presented in the assessment was difficult to interpret in light of the overlap in credible intervals of the yields of the various options. To solve this issue, the authors developed a new projection method to perform the 3M cod projections and compute risk, projecting a single catch value instead of a distribution of catches.
One of the problems raised by the Scientific Council is how to estimate the inputs to be used in the projections due to the rapid changes in the biology of this stock, especially from 2007. Normally the last three years mean is used as input for these parameters. The changes in the biological parameters cause problems in the projections results as the inputs used for the projected years usually are overestimated, leading to an overestimation of the SSB and the associated TAC for a given F. To solve this issue, the authors suggest using just the last year inputs in the projections. An attempt to add uncertainty in the last year inputs was made, examining the interannual changes observed in past years in the inputs and taking into consideration the correlation between them. The uncertainty and the risk in the results increases considerably and it was suggested to study deeply this method before its implementation.
The authors conclude that caution should be exercised concerning the results of the projections for this stock. If uncertainty in the projection inputs is implemented, advice for more than one year will not be accurate due to the issues identified.Executive Agency for Small and Medium-sized Enterprises (EASME)Versión del edito
