Analysis of the ICES short-term forecasts of North Sea plaice and sole: dealing with the 'current year' assumption

The F1 working package of the F-project is concerned with the improvement of stock assessment of plaice and sole. The full range of problems of uncertainty and bias in the stock assessment will be analysed through a series of small investigations of single problems. The present report deals with the “current year” assumption in the short-term forecast. From this study we conclude that in order to minimise the prediction error in the short-term forecast, given the uncertainty and bias in the VPA, the status quo F assumption should be preferred. We also found that the quality of the outcome of the VPA itself plays a large role in the quality of the forecast. Further study of the uncertainty and bias in the stock assessment, as planned in the F-project, is clearly necessary.