EU-Norway request - Management Plan for North Sea whiting
Recruitment for North Sea whiting is considered to be low (poor) when the geometric mean of the recent 3–5 years falls below 1.25 billion individuals at age 1. ICES considers that 4 years may be an appropriate period to respond to a change in recruitment. When such low recruitment occurs, even a reduction of 33% and 50% in fishing mortality had limited impact on the already low probability (i.e. between 7% and 8%) of the stock going below the lowest observed SSB in the time-series (Bloss = 100 000 t). Using a constant F = 0.27 in the long term resulted in around 5% probability of SSB falling below Bloss, irrespective of changes in the recruitment regime but providing that recruitment remained within the range of observed values. Removing TAC constraints when the recruitment becomes low reduces the probability of the stock falling below Bloss. In all cases examined, the reductions in the probabilities of the stock falling below the lowest SSB observed are small.
Published under the auspices of the following ICES Steering Group or Committee