| Summary: | The workshop on management strategy evaluation for the mackerel in subareas 1–7 and 14, and in divisions 8.a–e and 9.a (Northeast Atlantic), WKMACMSE, chaired by Carmen Fernández, was convened to prepare the technical basis needed by ICES to respond to the request from Norway, the EU and the Faroe Islands concerning a long-term management strategy for mackerel. It met in Copenhagen, Denmark, during April 28–29 2017, and was attended by 20 participants, including two reviewers. The workshop addressed its terms of reference, with the following main outcomes: The fishing mortality reference points were evaluated according to the ICES guide-lines and this resulted in their values being updated. The reference points were calculated using the same simulation tool used for the mackerel management strategy evaluation; this was to ensure there is consistency between the derivation of the fishing mortality reference points and the evaluation of harvest control rules that may form the basis of a future management strategy for this stock. The set of harvest control rules indicated in the request, based on (F target , B trigger ) combinations, was evaluated. The evaluations included scenarios without and with densi-ty-dependence in the weights of mackerel, as this was part of the request. The workshop concluded that the scenario based on the weights from the last five years (2011–2015), which are low, should be the base case from which most conclusions for the advice should be drawn. This is also in line with the approach followed during the previous ICES evaluation of a management strategy for mackerel, in 2014. The results indicate increasing risk (meaning P(SSBlim) when going from the short term to the long term, which is expected given the currently high stock size. For any given level of risk, there are multiple (F target , B trigger ) combinations that achieve that risk, with higher values of F target associated with higher B trigger values and vice versa. The workshop identified the precautionary combinations, defined ...
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